THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE Volume 17,Number 2,2011,pp.101-108 Review Article Mary Ann Liebert,Inc. D0110.1089/acm.2009.0277 A Systematic Review on the Anxiolytic Effects of Aromatherapy in People with Anxiety Symptoms Yuk-Lan Lee,BSc,Ying Wu,BSc,Hector W.H.Tsang,PhD:Ada Y.Leung,MA:and W.M.Cheung,PhD2 Abstract Purpose:We reviewed studies from 1990 to 2010 on using aromatherapy for people with anxiety or anxiety symptoms and examined their clinical effects. Methods:The review was conducted on available electronic databases to extract journal articles that evaluated the anxiolytic effects of aromatherapy for people with anxiety symptoms. Results:The results were based on 16 randomized controlled trials examining the anxiolytic effects of aroma- therapy among people with anxiety symptoms.Most of the studies indicated positive effects to quell anxiety.No adverse events were reported. Conclusions:It is recommended that aromatherapy could be applied as a complementary therapy for people with anxiety symptoms.Further studies with better quality on methodology should be conducted to identify its clinical effects and the underlying biologic mechanisms. Introduction Unfortunately,the effect is not at all conclusive based on available information.8 ymaend bhvr Recently,a remarkable increase in the use of comple- mentary and alternative medicine(CAM)around the globe is components.About 4%6%of the global population suffer evidenced.Aromatherapy is a commonly used CAM that has from various forms of anxiety disorders with such symptoms long been regarded as a popular means of treatment for as high blood pressure,elevated heart rate,sweating,fatigue, anxiety.It involves the therapeutic use of essential,aromatic unpleasant feeling,tension,irritability,and restlessness.2 If oils,commonly combined with therapeutic massage and untreated,40%50%of the patients would progress to de- excitation of the olfactory system,to induce relaxation and pression and have suicidal thoughts.3 The symptoms bring thus quell certain anxiety symptoms.Aromatherapy is huge negative impact to their families,social,and occupa- claimed to be beneficial to the mental,psychologic,spiritual, tional roles.National statistics show that in the United States, and social aspects,although they are less quantitatively anxiety disorders incurred $46.6 billion direct and indirect measurable.With respect to safety,it is reported that that costs each year,which constituted nearly one third of the aromatherapy is relatively free of adverse effects compared nation's total mental health expenses. with conventional drugs.10 Pharmacologic and psychologic treatments have remained Unlike conventional medicine,the effectiveness of aro- the conventional interventions to treat anxiety disorders for matherapy remains unclear and is still under intensive re- the past 30 years."However,pharmacologic treatment cau- search.To date,there is only one relevant review on ses many side-effects.For example,benzodiazepine,a pop- aromatherapy for depression.Although depression and ular medication with powerful anxiolytic effects,has been anxiety are usually co-occurring,a separate systematic re- well known for its side-effects including sedation,muscle view on the anxiolytic effects of aromatherapy is still needed. relaxation,headache,and ataxia.These side-effects signifi- To date,there has not been a systematic review on the an- cantly reduce adherence of the patients.Another problem is xiolytic effects of aromatherapy.The purpose of the current that some anti-anxiety drugs are potentially addictive.Re- review is to fill the gap by unraveling the effectiveness occurrence of anxiety symptoms will result from removal of of aromatherapy on relieving anxiety symptoms.Based on the drugs.?Psychologic treatment,especially cognitive be- extant literature,the evidence was integrated so as to aid havior therapy,is the main alternative to drug therapy. in gaining a better understanding on the clinical use of 'Neuropsychiatric Rehabilitation Laboratory,Department of Rehabilitation Sciences,The Hong Kong Polytechnic University,Hong Kong. 2Faculty of Education,The University of Hong Kong,Hong Kong. 101
Review Article A Systematic Review on the Anxiolytic Effects of Aromatherapy in People with Anxiety Symptoms Yuk-Lan Lee, BSc,1 Ying Wu, BSc,1 Hector W.H. Tsang, PhD,1 Ada Y. Leung, MA,1 and W.M. Cheung, PhD2 Abstract Purpose: We reviewed studies from 1990 to 2010 on using aromatherapy for people with anxiety or anxiety symptoms and examined their clinical effects. Methods: The review was conducted on available electronic databases to extract journal articles that evaluated the anxiolytic effects of aromatherapy for people with anxiety symptoms. Results: The results were based on 16 randomized controlled trials examining the anxiolytic effects of aromatherapy among people with anxiety symptoms. Most of the studies indicated positive effects to quell anxiety. No adverse events were reported. Conclusions: It is recommended that aromatherapy could be applied as a complementary therapy for people with anxiety symptoms. Further studies with better quality on methodology should be conducted to identify its clinical effects and the underlying biologic mechanisms. Introduction Anxiety is a psychologic and physiologic state characterized by cognitive, somatic, emotional, and behavioral components.1 About 4%–6% of the global population suffer from various forms of anxiety disorders with such symptoms as high blood pressure, elevated heart rate, sweating, fatigue, unpleasant feeling, tension, irritability, and restlessness.2 If untreated, 40%–50% of the patients would progress to depression and have suicidal thoughts.3 The symptoms bring huge negative impact to their families, social, and occupational roles. National statistics show that in the United States, anxiety disorders incurred $46.6 billion direct and indirect costs each year, which constituted nearly one third of the nation’s total mental health expenses.4 Pharmacologic and psychologic treatments have remained the conventional interventions to treat anxiety disorders for the past 30 years.5 However, pharmacologic treatment causes many side-effects. For example, benzodiazepine, a popular medication with powerful anxiolytic effects, has been well known for its side-effects including sedation, muscle relaxation, headache, and ataxia.6 These side-effects signifi- cantly reduce adherence of the patients. Another problem is that some anti-anxiety drugs are potentially addictive. Reoccurrence of anxiety symptoms will result from removal of the drugs.7 Psychologic treatment, especially cognitive behavior therapy, is the main alternative to drug therapy.5 Unfortunately, the effect is not at all conclusive based on available information.8 Recently, a remarkable increase in the use of complementary and alternative medicine (CAM) around the globe is evidenced. Aromatherapy is a commonly used CAM that has long been regarded as a popular means of treatment for anxiety. It involves the therapeutic use of essential, aromatic oils, commonly combined with therapeutic massage and excitation of the olfactory system, to induce relaxation and thus quell certain anxiety symptoms.9 Aromatherapy is claimed to be beneficial to the mental, psychologic, spiritual, and social aspects, although they are less quantitatively measurable. With respect to safety, it is reported that that aromatherapy is relatively free of adverse effects compared with conventional drugs.10 Unlike conventional medicine, the effectiveness of aromatherapy remains unclear and is still under intensive research. To date, there is only one relevant review on aromatherapy for depression.11 Although depression and anxiety are usually co-occurring, a separate systematic review on the anxiolytic effects of aromatherapy is still needed. To date, there has not been a systematic review on the anxiolytic effects of aromatherapy. The purpose of the current review is to fill the gap by unraveling the effectiveness of aromatherapy on relieving anxiety symptoms. Based on extant literature, the evidence was integrated so as to aid in gaining a better understanding on the clinical use of 1 Neuropsychiatric Rehabilitation Laboratory, Department of Rehabilitation Sciences, The Hong Kong Polytechnic University, Hong Kong. 2 Faculty of Education, The University of Hong Kong, Hong Kong. THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE Volume 17, Number 2, 2011, pp. 101–108 ª Mary Ann Liebert, Inc. DOI: 10.1089/acm.2009.0277 101
102 LEE ET AL. aromatherapy as a CAM to treat people suffering from in anxiety symptoms were observed in at least one of the anxiety symptoms outcome measures between the study groups Methods Results Literature search Study description Studies used in this review were extracted from MED- The numbers of citations returned from the database LINE,Social Sciences Citation Index,Science Citation In- search were 70,73,and 42 for MEDLINE,SSCI+SCI,and dex,Psyinfo,PsyARTICLES,Journals@Ovid,MD Consult, others(Psyinfo,PsyARTICLES,Journals@Ovid,MD Consult, ScienceDirect,EBSCOHOST,and Handbook of Psychiatry, ScienceDirect,EBSCOHOST,and Handbook of Psychiatry), from 1990 to 2008,using keywords "anxiety disorder," respectively,in March 2010.Fifty-two(52)relevant publica- “anxiety,”"anxious symptom"or"anxiolytic effects'”and tions were extracted for further evaluation.After abstract "aromatherapy","aroma,"or "essence oil."Only English screening at the first stage and full-text screening at the publications were included.Potential titles were retrieved for second stage,16 studies met the inclusion criteria.Figure 1 the second stage of review.The titles and the available ab- summarizes the selection process of the eligible RCTs stracts were then independently reviewed.Neither of the Table 1 summarizes the methods and results of the 16 reviewers was blind to the author name,institution,and/or qualified RCTs.The total number of subjects involved was the journal. 25,377,in which the female-to-male ratio was 24,887:490.The The target was to extract randomized controlled trials age of the participants ranged from 18 to 90 years (RCT)that used aromatherapy as the intervention to relieve (M=47.77).All subjects suffered from obvious anxiety anxiety symptoms that were measured by validated inven- symptoms.Patients receiving palliative care were reported in tories.A study was operationally defined as a RCT in this three studies.16-18 Healthy volunteers with experimentally review if the allocation of participants to treatment and comparison groups was reported to be randomized,the ue sample size was not less than 10 in each arm,the participants cruited different types of clients,including mothers in labor, were aged 18 or older,and anxiety was included as the postpartum mothers,women prepared for surgical abortion, outcome measure.Studies that did not use any type of participants prepared for endoscopy procedure,patients comparison group,were qualitative in nature,and were prepared for dental procedures,patients with cancer during systematic review or meta-analysis were excluded. radiotherapy,nursing students attended for stressful surgical disease examination,patients with cancer with clinically di- Quality assessment agnosed with anxiety/depression,patients with moderate Studies selected based on the above criteria,and methods and severe dementia,patients in hematology transplant unit, were evaluated for methodological vigor.Guidelines set out and patients primarily diagnosed with generalized anxiety by Glasziou et al.12 were followed,and the quality of the disorder.The types of aromatherapy administration in the studies was assessed by reviewing whether they fulfilled the RCTs included aromatherapy massage,inhalation,tablet criteria of control randomization,allocation concealment, intake,and footbath.The intervention duration of aroma- intention to treat,and blindedness.Adequately concealed therapy massage ranged from 20 minutes to 1 hour,and the RCT means that the trial had a clear description of its allo- duration of inhalation ranged from 5 minutes to 1 hour.The cation procedure,central randomization,and allocation from most commonly used essential oil used in these studies was site apart from the study area and/or blinding allocation lavender.17.19,2 procedure.An RCT is considered to have used intention-to- treat analysis if all the randomized participants were ana- Outcomes lyzed with no differences between the treatment allocation before and after application of treatment procedure.13 A Only 14 studies adopted a control group with a compati- study was classified as "single blind"if the outcome measure ble"conventional therapy"or a"placebo,"and the remaining was conducted by an assessor who was blind to the treat- two studies used a control group with"no active treatment." ment allocation while the participants were not blind to the Fourteen(14)studies reported positive findings as to the treatment.A study was classified as "double blind"if both anxiolytic effects of aromatherapy6 while the re the assessor of outcome measure and the participants were maining two studies reported no effect of the aroma- blind to the treatment allocation.A study was considered therapy toward anxiety symptoms.In comparing changes not blind if neither the assessor nor the participants were and improvement between the aromatherapy and control blind to the outcome measure and treatment allocation, groups providing no active interventions,the subjects who respectively.14 received aromatherapy usually showed better outcomes than those in the control groups.However,when comparing the Data synthesis effect of aromatherapy to a conventional treatment or a placebo (e.g.,massage with carrier oil,inactive coated tab- Due to heterogeneity of the study populations,psycho- lets,benzodiazepine,sniff a hair conditioner,music therapy, metric instruments,and intervention trials,quantitative etc.),the results were inconsistent.Seven (7)studies indi- analysis on the effect size was not performed.However, cated that aromatherapy had benefits that were superior to qualitative analysis using the Sjosten method15 was em- conventional therapy or placebo.19-2224,26,27 In contrast,five ployed to classify interventions as having positive,negative, studies17,18,28-30 reported that the therapeutic effects between or no effect as determined by whether significant differences massage group and aromatherapy group were similar.One
aromatherapy as a CAM to treat people suffering from anxiety symptoms. Methods Literature search Studies used in this review were extracted from MEDLINE, Social Sciences Citation Index, Science Citation Index, Psyinfo, PsyARTICLES, Journals@Ovid, MD Consult, ScienceDirect, EBSCOHOST, and Handbook of Psychiatry, from 1990 to 2008, using keywords ‘‘anxiety disorder,’’ ‘‘anxiety,’’ ‘‘anxious symptom’’ or ‘‘anxiolytic effects’’ and ‘‘aromatherapy’’, ‘‘aroma,’’ or ‘‘essence oil.’’ Only English publications were included. Potential titles were retrieved for the second stage of review. The titles and the available abstracts were then independently reviewed. Neither of the reviewers was blind to the author name, institution, and/or the journal. The target was to extract randomized controlled trials (RCT) that used aromatherapy as the intervention to relieve anxiety symptoms that were measured by validated inventories. A study was operationally defined as a RCT in this review if the allocation of participants to treatment and comparison groups was reported to be randomized, the sample size was not less than 10 in each arm, the participants were aged 18 or older, and anxiety was included as the outcome measure. Studies that did not use any type of comparison group, were qualitative in nature, and were systematic review or meta-analysis were excluded. Quality assessment Studies selected based on the above criteria, and methods were evaluated for methodological vigor. Guidelines set out by Glasziou et al.12 were followed, and the quality of the studies was assessed by reviewing whether they fulfilled the criteria of control randomization, allocation concealment, intention to treat, and blindedness. Adequately concealed RCT means that the trial had a clear description of its allocation procedure, central randomization, and allocation from site apart from the study area and/or blinding allocation procedure. An RCT is considered to have used intention-totreat analysis if all the randomized participants were analyzed with no differences between the treatment allocation before and after application of treatment procedure.13 A study was classified as ‘‘single blind’’ if the outcome measure was conducted by an assessor who was blind to the treatment allocation while the participants were not blind to the treatment. A study was classified as ‘‘double blind’’ if both the assessor of outcome measure and the participants were blind to the treatment allocation. A study was considered not blind if neither the assessor nor the participants were blind to the outcome measure and treatment allocation, respectively.14 Data synthesis Due to heterogeneity of the study populations, psychometric instruments, and intervention trials, quantitative analysis on the effect size was not performed. However, qualitative analysis using the Sjo¨ sten method15 was employed to classify interventions as having positive, negative, or no effect as determined by whether significant differences in anxiety symptoms were observed in at least one of the outcome measures between the study groups. Results Study description The numbers of citations returned from the database search were 70, 73, and 42 for MEDLINE, SSCIþ SCI, and others (Psyinfo, PsyARTICLES, Journals@Ovid, MD Consult, ScienceDirect, EBSCOHOST, and Handbook of Psychiatry), respectively, in March 2010. Fifty-two (52) relevant publications were extracted for further evaluation. After abstract screening at the first stage and full-text screening at the second stage, 16 studies met the inclusion criteria. Figure 1 summarizes the selection process of the eligible RCTs. Table 1 summarizes the methods and results of the 16 qualified RCTs. The total number of subjects involved was 25,377, in which the female-to-male ratio was 24,887:490. The age of the participants ranged from 18 to 90 years (M ¼ 47.77). All subjects suffered from obvious anxiety symptoms. Patients receiving palliative care were reported in three studies.16–18 Healthy volunteers with experimentally induced stress were the second most popular client types that were reported in two studies.19,20 Other studies recruited different types of clients, including mothers in labor, postpartum mothers, women prepared for surgical abortion, participants prepared for endoscopy procedure, patients prepared for dental procedures, patients with cancer during radiotherapy, nursing students attended for stressful surgical disease examination, patients with cancer with clinically diagnosed with anxiety/depression, patients with moderate and severe dementia, patients in hematology transplant unit, and patients primarily diagnosed with generalized anxiety disorder. The types of aromatherapy administration in the RCTs included aromatherapy massage, inhalation, tablet intake, and footbath. The intervention duration of aromatherapy massage ranged from 20 minutes to 1 hour, and the duration of inhalation ranged from 5 minutes to 1 hour. The most commonly used essential oil used in these studies was lavender.17,19,21–25 Outcomes Only 14 studies adopted a control group with a compatible ‘‘conventional therapy’’ or a ‘‘placebo,’’ and the remaining two studies used a control group with ‘‘no active treatment.’’ Fourteen (14) studies reported positive findings as to the anxiolytic effects of aromatherapy;16–22,24,26–31 while the remaining two studies23,25 reported no effect of the aromatherapy toward anxiety symptoms. In comparing changes and improvement between the aromatherapy and control groups providing no active interventions, the subjects who received aromatherapy usually showed better outcomes than those in the control groups. However, when comparing the effect of aromatherapy to a conventional treatment or a placebo (e.g., massage with carrier oil, inactive coated tablets, benzodiazepine, sniff a hair conditioner, music therapy, etc.), the results were inconsistent. Seven (7) studies indicated that aromatherapy had benefits that were superior to conventional therapy or placebo.19–22,24,26,27 In contrast, five studies17,18,28–30 reported that the therapeutic effects between massage group and aromatherapy group were similar. One 102 LEE ET AL.
ANXIOLYTIC EFFECTS OF AROMATHERAPY 103 185 publications identified MEDLINE®(I=7O) SSCI+SCI(n=73) Other Databases (n =42) 133 publications excluded because they were not studies of anxiety or animal studies involved 52 full text articles for further evaluation 28 publications excluded for reasons below: No control group(n=12) Literature review (n 6) Sample size less than 10 in each arm (n =5) FIG.1.Flowchart of randomized controlled trials (RCTs)selection Not written in English (n=2) process.SSCI,Social Sciences Cita- Qualitative study (n=1) tion Index;SCI,Science Citation Index. No randomization in subject allocation (n=1) 24 full text articles for further evaluation 8 publications excluded because there were no obvious anxiety symptoms in baseline measurement of the subjects 16 RCTs included and reviewed (1)study16reported that the anxiolytic effect of massage with therapists in the studies did not belong to the research team carrier oil only was significantly better than those receiving and did not need to conduct assessments of the subjects in massage with essential oil.One study reported that an oral order to ensure the double-blindedness.Seven(7)of the 16 lavender oil capsule is as effective as lorazepam,a benzodi- studies did not mention whether blinding techniques were azepine,in adults with generalized anxiety disorder.31 applied Intention-to-treat analysis was employed Two (2)studies had follow-up data after the treatment.in 11 studies.4 One (1)study mentioned the high Both of them suggested that no long-term effect was evi- dropout rate due to the long research period.In addition,the denced,and aromatherapy did not appear to confer benefit number of subjects recruited for individual studies varied on anxiety. greatly,from 24 to 23,857. Study quality Pooled effect size All studies applied random allocation.Seven of the 16 State Anxiety Inventory (SAl)was commonly used in the studies nevertheless had no clear description on the ran- 16 reviewed studies.Pooled effect size of the outcome mea- domization procedures.Only one study de sure of SAI is conducted from pre-and post-means and scribed the concealment of allocation procedure,but the standard deviations of the control and treatment groups of description was inadequate.Double-blindedness during three studies.18,26,27 Other studies are not included because outcome assessment was described in three studies corresponding authors could not be contacted for further and single-blindedness in six studies.21,222628 The massage information.Pooled effect size is shown in Table 2
(1) study16 reported that the anxiolytic effect of massage with carrier oil only was significantly better than those receiving massage with essential oil. One study reported that an oral lavender oil capsule is as effective as lorazepam, a benzodiazepine, in adults with generalized anxiety disorder.31 Two (2) studies26,28 had follow-up data after the treatment. Both of them suggested that no long-term effect was evidenced, and aromatherapy did not appear to confer benefit on anxiety. Study quality All studies applied random allocation. Seven of the 16 studies nevertheless had no clear description on the randomization procedures.16,17,19,22,23,25,29 Only one study21 described the concealment of allocation procedure, but the description was inadequate. Double-blindedness during outcome assessment was described in three studies20,30,31 and single-blindedness in six studies.21,22,26,28 The massage therapists in the studies did not belong to the research team and did not need to conduct assessments of the subjects in order to ensure the double-blindedness. Seven (7) of the 16 studies did not mention whether blinding techniques were applied.16–19,23,27,29 Intention-to-treat analysis was employed in 11 studies.19–24,26–30 One (1) study16 mentioned the high dropout rate due to the long research period. In addition, the number of subjects recruited for individual studies varied greatly, from 24 to 23,857. Pooled effect size State Anxiety Inventory (SAI) was commonly used in the 16 reviewed studies. Pooled effect size of the outcome measure of SAI is conducted from pre- and post- means and standard deviations of the control and treatment groups of three studies.18,26,27 Other studies are not included because corresponding authors could not be contacted for further information. Pooled effect size is shown in Table 2. 185 publications identified MEDLINE® (n = 70) SSCI + SCI (n = 73) Other Databases (n = 42) 133 publications excluded because they were not studies of anxiety or animal studies involved 52 full text articles for further evaluation 16 RCTs included and reviewed 8 publications excluded because there were no obvious anxiety symptoms in baseline measurement of the subjects 24 full text articles for further evaluation 28 publications excluded for reasons below: No control group (n =12) Literature review (n = 6) Sample size less than 10 in each arm (n =5) Not written in English (n = 2) Qualitative study (n = 1) No randomization in subject allocation (n = 1) FIG. 1. Flowchart of randomized controlled trials (RCTs) selection process. SSCI, Social Sciences Citation Index; SCI, Science Citation Index. ANXIOLYTIC EFFECTS OF AROMATHERAPY 103
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Table 1. Summary of Randomized Controlled Trials (RCTs) Using Aromatherapy as Complementary and Alternative Medicine for Treating Anxiety Symptoms Study No. subjects No. control Mean age % Women Country Type of intervention Aromatherapy elements Type of subjects Instrument Type of study Individual/ group Follow-up after intervention Duration Session Burns et al.29 8058 15,799 Not mentioned 100 UK Aroma inhalation/ massage/ foot-bath of essential oil Rose, jasmine, chamomile, eucalyptus, lemon, mandarin, clary sage, frankincense, lavender, and peppermint Mothers presented in labor Mother’s rating of effectiveness; outcome of labor RCT Individual No 8 years 1 Burnett et al.19 1. Rosemary group: 25 2. Lavender group: 23 25 Ranged from 18 to 31 57.53 United States Aroma inhalation Lavender and rosemary Volunteers with laboratory- induced stress Profile of Mood States & heart rate RCT Individual No 10 minutes Not men- tioned Fujii et al.22 14 14 78 67.86 Japan Aroma inhalation oil Lavender Patients with moderate and severe dementia Neuropsychiatric Inventory—NPI (structured interview with caregiver) RCT Individual No 1 hour 84 sessions Graham et al.25 1. Carrier oil with fractionated oils group: 111 2. Carrier oil group: 111 3. Pure essential oils group: 111 65 47.92 Australia Mildly to moderately anxious patients with cancer during radiotherapy Lavender, bergamot, and cedarwood Essential oils of lavender, bergamot, and cedarwood Hospital Anxiety and Depression scale – HADS; Somatic and Psychological Health ReportSPHERE RCT Group No Not mentioned 1 Imura et al.27 16 20 31.9 100 Japan Aromatherapy massage Neroli and lavender Postpartum mother STAI-StateAnxiety In- ventory Quasi- experimental study Individual No 30 minutes Not mentioned Kennedy et al.20 24 received 3 separate single doses separated by a 7-day washout period 23.48 50 UK Aroma tablet intake M. officinalis and V. officinalis Melissa officinalis and Valeriana officina STAI-StateAnxiety In- ventory RCT Group No 5 study days separated by 7 days washout period 5 Kutlu et al.21 50 45 20.51 73.68 Turkey Aroma inhala- tion Lavender fragrance Nursing stu- dents who attended the stressful surgical disease examination STAI–State Anxiety Inventory RCT Group No 60 minutes 1 Kyle16 1. Massage with essential oil group: 15 2. Aroma stone with essential oil group:10 12 Not mentioned 100 UK Aromatherapy massage/ aromastone Santalum album oil Palliative care patients STAI–State Anxiety Inventory RCT Individual No 4 weeks 4 Lehrner et al.24 1. Lavender group: 48 2. Orange odor group: 50 3. Music group: 49 51 40.5 50 Austria Aroma inhalation/music therapy Orange oil and lavender oil Patients waiting for dental procedures STAI-State Anxiety Inventory Mehrdi- mensionale Befindlichkeitsfragebogen–MDBF RCT Group No Not men- tioned Not men- tioned (continued) 104
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Table 1. (Continued) Study No. subjects No. control Mean age % Women Country Type of intervention Aromatherapy elements Type of subjects Instrument Type of study Individual/ group Follow-up after intervention Duration Session Muzzarelli et al.23 61 57 52 50 United States Aroma inhalation Lavender oil 5 minutes STAI–State Anxiety Inventory RCT Individual No 5 minutes Not men- tioned Soden et al.17 1. Massage with essential oil and an inert carrier oil group: 16 2. Massage with an inert carrier oil group: 13 13 Ranged from 44 to 85 76.19 UK Aromatherapy massage Lavender essential oil Patients with specialist palliative care unit Hospital Anxiety and Depression–HAD RCT Individual No 30 minutes 4 Stringer et al.28 1. Aromatherapy massage: 13 2. Massage with Base oil: 13 13 Ranged from 19 to 70 58.97 UK Aromatherapy massage Varied from 40 oil blends Patients in the Hematology Transplant unit 1. Serum cortisol and prolactin levels 2. Quality of Life (EORTC QLQ– C30) 3. Semistructured interview 4. Therapist’s sessional diary RCT Individual Yes (follow-up ½ hourly for 2 hours and at 24 hours) 20 minutes, the whole experiment took 24 hours 1 Wiebe30 36 30 26.5 100 Canada Aroma inhalation Vetivert, ber- gamot, and geranium oil Women waiting for surgical abortions with preoperative anxiety Verbal Anxiety Scale RCT Group No 10 minutes Not mentioned Wilkinson et al.18 43 44 53.5 89.66 UK Aromatherapy massage Roman chamo- mile essential oil (% was not mentioned) Palliative care patients 1. State–Trait Anxiety Inventory 2. Rotterdam Symptom Checklist 3. Semistructured questionnaire RCT Individual No 3 weeks Not mentioned Wilkinson et al.26 144 144 52.1 86.81 UK Aromatherapy massage Not specified (20 essential oil) Cancer patients 1. State anxiety inventory 2. Center for Epidemiological Studies–depression 3. Quality of life (EORTC) RCT Individual Yes 4 weeks 4 Woelk et al.31 40 37 Not mentioned 76.6 Germany Aroma tablet intake Lavender Patients pri- marily diagnosis of generalized anxiety disorder 1. Hamilton Anxiety Rating Scale 2. Self-rating Anxiety Scale 3. Peen Sate Worry Questionnaire 4. SF-36 Health Survey Questionnaire 5. Clinical Global Impressions of severity of disorder 6. Sleep diary RCT Group No 6 weeks Not mentioned EORTC, European Organization for Research on the Treatment of Cancer; QLQ-C30, Quality of Life Questionnaire—C30. 105
106 LEE ET AL. TABLE 2.POOLED EFFECT SIZE OF AROMATHERAPY tactile stimulation.Four (4)studies made comparisons be- MASSAGE STUDIES WITH STATE ANXIETY tween massage and aromatherapy massage.Three (3)of INVENTORY OUTCOME MEASURE them stated a tendency for aromatherapy massage to be Study Effect size Pooled effect size slightly more effective than the "placebo."One (1)reported that massage alone had slightly better anxiolytic effect than Imura et al.27 -1.617 aromatherapy massage.However,the differences were Wilkinson et al.18 -0.0708 modest and could have been attributed to flaws in the study Wilkinson et al.26 -0.5030 -0.5103 design.It is therefore important to determine the best mo- dalities of aromatherapy in future studies.Comparison be- tween inhalation,aromatherapy massage,oral intake,and a Discussion control group with a compatible "conventional treatment/ placebo"in future studies will be necessary to rule out the Aromatherapy is the most commonly used CAM for effects of nonspecific factors and to unify the modalities of treating anxiety symptoms around the world.32 Our review aromatherapy. reveals that aromatherapy shows a positive anxiolytic ef- The quality of the studies'design prevented drawing fect for patients with anxiety symptoms and more impor- firm valid conclusions as to the clinical efficacy of aro- tantly,it is a safe intervention,and no participants in the matherapy.The size of samples varied largely in the studies reported any adverse effects.However,drawing present studies.Except for one study with a large number conclusions on the effectiveness of aromatherapy for re- of participants (n=23,857),five studies used only a small lieving anxiety symptoms should be done with care and sample size (n=24,n=28,n=34,n=36,n=39).Also,the caution. gender distribution among the participants was uneven, This review shows that there are insufficient clinical trials with the female subjects outnumbering (n=24,887)the male examining the effects of aromatherapy among people with subjects (n=490)on the whole (n=25,377)among the five anxiety disorders as the primary illness.All of the 16 studies reviewed studies.The reason is that one of the reviewed in our review in fact examined the effects of aromatherapy studies with the largest sample size (n=23,857)involved on secondary anxiety symptoms in various types of partici- only female subjects who were in fact mothers in labor. pants,including people with cancer,dementia,postpartum Other than this study,the distribution of gender of other mothers,and healthy volunteers.In addition,the anxiety studies was even.Further research should employ compa- levels of the participants differed significantly from mild to rable numbers of male and female participants.Studies also moderate in the pretests.The effectiveness of aromatherapy showed significant differences in the duration of treatment. could hardly be compared among participants with different One (1)study lasted only 5 minutes,while two studies levels of anxiety.Improvement in anxiety symptoms among lasted 60 minutes.It is uncertain whether the duration of participants with mild anxiety tended to be insignificant.In aromatherapy treatment between studies would have contrast,participants with high levels of psychologic distress affected the outcomes.Furthermore,the studies adopted responded better to aromatherapy interventions.17 To im- different types of essential oil.It is unknown whether the prove the quality of research efforts in the future,the level effects were due to a specific essential oil (e.g,lavender, of severity of anxiety can be raised to moderate or greater in etc.)or the general properties of various essential oils. the recruitment of participants to assure the validity of the Although our studies were all RCTs in nature,there were results. obvious methodological limitations.To provide further evi- The Spielberger State-Trait Anxiety Inventory,adopted as dence for advocating aromatherapy as an effective com- the assessment tool on evaluating anxiety levels in eight plementary or alternative treatment to reduce anxiety studies,was the most commonly used among the 16 studies. symptoms,studies with stricter and more vigorous proce- It is reported to be a reliable and valid self-rating assessment dures in allocation concealment and blinding should be in research and clinical practice.33 The meta-analysis of implemented.Compliance to the therapy should be exam- pooled effect size in the current study shows that aroma- ined more thoroughly by intention-to-treat analysis. therapy massage has a median treatment effect for anxiety. Notwithstanding the promising therapeutic effects of However,it should be noted that the pool effect size is ob- aromatherapy,there has not been literature that could tained from three studies with different essential oils and provide a sound biologic rationale for the use of aroma- treatment duration. therapy as a complementary and alternative intervention. As to the administration of aromatherapy,six studies The psychobiologic mechanism underlying the anxiolytic employed aromatherapy massage and seven studies used the effect remains unclear.According to previous research,34 method of inhalation.Other modalities such as internal or y-aminobutyric acid (GABA),one of the brain neurotrans- oral application and footbath were mentioned in three mitters,has an inhibitory effect upon the nervous system studies.Yim et al.and Imura et al.27 raised the question of and hence may be used to calm the overstimulated nervous whether the effect was due to the aromatherapy alone or its system under tension and stress.Previous research ef- interaction effect with massage.In this review,different im- forts35.36 have suggested that some essential oils (e.g.,lav- plementations of aromatherapy have made the effect non- ender,etc.)worked similarly to diazepam,which acts as the comparable and undifferentiated.It is obvious that agonist of GABA.One of the current authors'reviewed inhalation involved purely olfactory stimulation,internal studies3 also stated that an oral lavender oil capsule,si- intake involved both olfactory stimulation and body me- lexan,is as effective as lorazepam,which is a commonly tabolism,and footbath and aromatherapy massage consisted used benzodiazepine.Some studies hypothesized that the of olfactory stimulation,somatosensory stimulation,and anxiolytic effects may be due to the retrieval of pleasant
Discussion Aromatherapy is the most commonly used CAM for treating anxiety symptoms around the world.32 Our review reveals that aromatherapy shows a positive anxiolytic effect for patients with anxiety symptoms and more importantly, it is a safe intervention, and no participants in the studies reported any adverse effects. However, drawing conclusions on the effectiveness of aromatherapy for relieving anxiety symptoms should be done with care and caution. This review shows that there are insufficient clinical trials examining the effects of aromatherapy among people with anxiety disorders as the primary illness. All of the 16 studies in our review in fact examined the effects of aromatherapy on secondary anxiety symptoms in various types of participants, including people with cancer, dementia, postpartum mothers, and healthy volunteers. In addition, the anxiety levels of the participants differed significantly from mild to moderate in the pretests. The effectiveness of aromatherapy could hardly be compared among participants with different levels of anxiety. Improvement in anxiety symptoms among participants with mild anxiety tended to be insignificant. In contrast, participants with high levels of psychologic distress responded better to aromatherapy interventions.17 To improve the quality of research efforts in the future, the level of severity of anxiety can be raised to moderate or greater in the recruitment of participants to assure the validity of the results. The Spielberger State–Trait Anxiety Inventory, adopted as the assessment tool on evaluating anxiety levels in eight studies, was the most commonly used among the 16 studies. It is reported to be a reliable and valid self-rating assessment in research and clinical practice.33 The meta-analysis of pooled effect size in the current study shows that aromatherapy massage has a median treatment effect for anxiety. However, it should be noted that the pool effect size is obtained from three studies with different essential oils and treatment duration. As to the administration of aromatherapy, six studies employed aromatherapy massage and seven studies used the method of inhalation. Other modalities such as internal or oral application and footbath were mentioned in three studies. Yim et al.11 and Imura et al.27 raised the question of whether the effect was due to the aromatherapy alone or its interaction effect with massage. In this review, different implementations of aromatherapy have made the effect noncomparable and undifferentiated. It is obvious that inhalation involved purely olfactory stimulation, internal intake involved both olfactory stimulation and body metabolism, and footbath and aromatherapy massage consisted of olfactory stimulation, somatosensory stimulation, and tactile stimulation. Four (4) studies made comparisons between massage and aromatherapy massage. Three (3) of them stated a tendency for aromatherapy massage to be slightly more effective than the ‘‘placebo.’’ One (1) reported that massage alone had slightly better anxiolytic effect than aromatherapy massage. However, the differences were modest and could have been attributed to flaws in the study design. It is therefore important to determine the best modalities of aromatherapy in future studies. Comparison between inhalation, aromatherapy massage, oral intake, and a control group with a compatible ‘‘conventional treatment/ placebo’’ in future studies will be necessary to rule out the effects of nonspecific factors and to unify the modalities of aromatherapy. The quality of the studies’ design prevented drawing firm valid conclusions as to the clinical efficacy of aromatherapy. The size of samples varied largely in the present studies. Except for one study with a large number of participants (n ¼ 23,857), five studies used only a small sample size (n ¼ 24, n ¼ 28, n ¼ 34, n ¼ 36, n ¼ 39). Also, the gender distribution among the participants was uneven, with the female subjects outnumbering (n ¼ 24,887) the male subjects (n ¼ 490) on the whole (n ¼ 25,377) among the five reviewed studies. The reason is that one of the reviewed studies with the largest sample size (n ¼ 23,857) involved only female subjects who were in fact mothers in labor. Other than this study, the distribution of gender of other studies was even. Further research should employ comparable numbers of male and female participants. Studies also showed significant differences in the duration of treatment. One (1) study lasted only 5 minutes, while two studies lasted 60 minutes. It is uncertain whether the duration of aromatherapy treatment between studies would have affected the outcomes. Furthermore, the studies adopted different types of essential oil. It is unknown whether the effects were due to a specific essential oil (e.g., lavender, etc.) or the general properties of various essential oils. Although our studies were all RCTs in nature, there were obvious methodological limitations. To provide further evidence for advocating aromatherapy as an effective complementary or alternative treatment to reduce anxiety symptoms, studies with stricter and more vigorous procedures in allocation concealment and blinding should be implemented. Compliance to the therapy should be examined more thoroughly by intention-to-treat analysis. Notwithstanding the promising therapeutic effects of aromatherapy, there has not been literature that could provide a sound biologic rationale for the use of aromatherapy as a complementary and alternative intervention. The psychobiologic mechanism underlying the anxiolytic effect remains unclear. According to previous research,34 g-aminobutyric acid (GABA), one of the brain neurotransmitters, has an inhibitory effect upon the nervous system and hence may be used to calm the overstimulated nervous system under tension and stress. Previous research efforts35,36 have suggested that some essential oils (e.g., lavender, etc.) worked similarly to diazepam, which acts as the agonist of GABA. One of the current authors’ reviewed studies31 also stated that an oral lavender oil capsule, silexan, is as effective as lorazepam, which is a commonly used benzodiazepine. Some studies37 hypothesized that the anxiolytic effects may be due to the retrieval of pleasant Table 2. Pooled Effect Size of Aromatherapy Massage Studies with State Anxiety Inventory Outcome Measure Study Effect size Pooled effect size Imura et al.27 1.617 0.5103 Wilkinson et al.18 0.0708 Wilkinson et al.26 0.5030 106 LEE ET AL.
ANXIOLYTIC EFFECTS OF AROMATHERAPY 107 memories by particular smells associated with some essen- 15.Sjosten N,Kivel S.The effects of physical exercise on de- tial oils.The unclear biologic mechanisms explaining how pressive symptoms among the aged:A systematic review aromatherapy reduces anxiety symptoms leave room for Int J Geriatr Psychiatry 2006;21:410-418. further research. 16.Kyle G.Evaluating the effectiveness of aromatherapy in reducing levels of anxiety in palliative care patients:Results of a pilot study.Complement Ther Clin Pract 2006:12: Conclusions 148-155. As generally all of the 16 reviewed studies showed a 17.Soden K,Vincent K,Craske S,et al.A randomized con- positive result of aromatherapy on anxiety,it is re- trolled trial of aromatherapy massage in a hospice setting. commended that aromatherapy could be applied as a com- Palliat Med2004;18:87-92. plementary therapy for people with anxiety symptoms. 18.Wilkinson S,Aldridge J,Salmon I,et al.An evaluation of Although there is no conclusive evidence to show lasting aromatherapy massage in palliative care.Palliat Med 1999:13:409-417. effects of aromatherapy for treating anxiety,it may best be 19.Burnett KM,Solterbeck LA,Strapp CM.Scent and mood considered as a safe and pleasant intervention for those who can afford it and are prepared to pay for it. state following an anxiety-provoking task.Psychol Rep 200495:702-722 20.Kennedy DO,Little W,Haskell CF.Anxiolytic effects of a Disclosure Statement combination of Melissa officinalis and Valeriana officinalis No competing financial interests exist. during laboratory induced stress.Phytother Res 2006;20: 96-102 References 21.Kutlu AK,Yilmaz E,Cecen D.Effects of aroma inhalation on examination anxiety.Teach Learn Nurs 2008;3:125-130. 1.Seligman MEP,Walker EF,Rosenhan DL.Abnormal Psy- 22.Fujii M,Hatakeyama R,Fukuoka Y,et al.Lavender aroma chology.New York:W.W.Norton Company,2001. therapy for behavioral and psychological symptoms in de- 2.Smith M.Anxiety Attacks and Disorders:Guide to the Signs, mentia patients.Geriatr Gerontol Int 2008;8:136-138. Symptoms,and Treatment Options.Help Guide website. 23.Muzzarelli M,Force M,Sebold M.Aromatherapy and re- June 2008.Online document at:www.helpguide.org/ ducing preprocedural anxiety:A controlled prospective mental/anxiety_types_symptoms_treatment.htm Accessed study.Gastroenterol Nurs 2006;29:466-471. March 3,2009. 24.Lehrner J,Marwinski G,Lehr S,et al.Ambient odors of 3.Treating depression and anxiety in primary care.Prim Care orange and lavender reduce anxiety and improve mood in a Companion J Clin Psychiatry 2008;10:145-152. dental office.Physiol Behav 2005;86:92-95. 4.National Mental Health Association.Online document at: 25.Graham PH,Browne L,Graham J.Inhalation aromather- www.capefearhealthyminds.org/April 27,2009. apy during radiotherapy:Results of a placebo-controlled 5.Schmidt NB,Keough ME,Hunter LR,Funk AP.Physical double-blind randomized trial.I Clin Oncol 2003;21:2372- illness and treatment of anxiety disorders:A review.In: 2376. Zvolensky MJ,Smits J,eds.Series in Anxiety and Related 26.Wilkinson SM,Love SB,Westcombe AM,et al.Effective- Disorders:Anxiety in Health Behaviors and Physical Illness. ness of aromatherapy massage in the management of New York:Springer,2008:341-366. anxiety and depression in patients with cancer:A multi- 6.Lippa A,Czobor P,Beer B,et al.Selective anxiolysis pro- plecentre randomized controlled trial.I Clin Oncol 2007; duced by ocinaplon,a GABAA receptor modulator.Proc 25:532-538. Natl Acad Sci2005,102:7380-7385. 27.Imura M,Misao H,Ushijima H.The psychological effects of 7.Tyrer P.Anxiety:A Multidisciplinary Review.London:Im- aromatherapy-massage in healthy postpartum mothers. perial College Press,1999. I Midwifery Womens Health 2006;51:21-26. 8.Brown TA,Barlow DH.Long-term outcome in cognitive 28.Stringer J,Swindell R,Dennis M.Massage in patients un- behavioral treatment of panic disorder:Clinical predictors dergoing intensive chemotherapy reduces serum cortisol and alternative strategies for assessment.J Consult Clin and prolactin.Psycho-Oncology 2008;17:1024-1031. Psychol199563:754-765. 29.Burns EE,Blamey C,Ersser SJ.An investigation into the use 9.Kite SM,Maher EJ,Anderson K,et al.Development of an of aromatherapy on intrapartum midwifery practice.I Al- aromatherapy service at a cancer centre.Palliat Med tern Complement Med 2000;6:141-147. 1998:12:171-180. 30.Wiebe EE.A randomized trail of aromatherapy to reduce 10.Perry N,Perry E.Aromatherapy in the management of anxiety before abortion.Eff Clin Pract 2000;3:166-169. psychiatric disorders.CNS Drugs 2006;20:257-280. 31.Woelk H,Schlafke S.A multi-center,double-blind,rando- 11.Yim WC,Ng KZ,Tsang HWH,Leung AY.A review on the mised study of the lavender oil preparation silexan in effects of aromatherapy for patients with depressive symp- comparison to lorazepam for generalized anxiety disorder. toms.I Altern Complement Med 2009;15:187-195. Phytomedicine 2010:17:94-99. 12.Glasziou P,Irwig L,Bain CJ,Colditz G.Systematic Reviews 32.Hadfield N.The role of aromatherapy massage in reducing in Health Care:A Practical Guide.UK:Cambridge Uni- anxiety in patients with malignant brain tumors.Int I Palliat versity Press,2001. Nus2001;7:279-285. 13.Hollis S,Campbell F.What is meant by intention to treat 33.Fountoulakis KN.Reliability and psychometric properties analysis?Survey of published randomised controlled trials. of the Greek translation of the state-trait anxiety inven- BM01999319:670-674. tory form Y:Preliminary data.Ann Gen Psychiatry 2006; 14.Spatz C,Kardas EP.Research Methods in Psychology: 52. Ideas,Techniques,and Reports.New York:McGraw-Hill, 34.Vizi ES.Handbook of Neurochemistry and Molecular Neu- 2008. robiology.New York:Springer,2008
memories by particular smells associated with some essential oils. The unclear biologic mechanisms explaining how aromatherapy reduces anxiety symptoms leave room for further research. Conclusions As generally all of the 16 reviewed studies showed a positive result of aromatherapy on anxiety, it is recommended that aromatherapy could be applied as a complementary therapy for people with anxiety symptoms. Although there is no conclusive evidence to show lasting effects of aromatherapy for treating anxiety, it may best be considered as a safe and pleasant intervention for those who can afford it and are prepared to pay for it. Disclosure Statement No competing financial interests exist. References 1. Seligman MEP, Walker EF, Rosenhan DL. Abnormal Psychology. New York: W.W. Norton & Company, 2001. 2. Smith M. Anxiety Attacks and Disorders: Guide to the Signs, Symptoms, and Treatment Options. Help Guide website. June 2008. Online document at: www.helpguide.org/ mental/anxiety_types_symptoms_treatment.htm Accessed March 3, 2009. 3. Treating depression and anxiety in primary care. Prim Care Companion J Clin Psychiatry 2008;10:145–152. 4. National Mental Health Association. Online document at: www.capefearhealthyminds.org/ April 27, 2009. 5. Schmidt NB, Keough ME, Hunter LR, Funk AP. Physical illness and treatment of anxiety disorders: A review. In: Zvolensky MJ, Smits J, eds. Series in Anxiety and Related Disorders: Anxiety in Health Behaviors and Physical Illness. New York: Springer, 2008:341–366. 6. Lippa A, Czobor P, Beer B, et al. Selective anxiolysis produced by ocinaplon, a GABAA receptor modulator. Proc Natl Acad Sci 2005;102:7380–7385. 7. Tyrer P. Anxiety: A Multidisciplinary Review. London: Imperial College Press, 1999. 8. Brown TA, Barlow DH. Long-term outcome in cognitive behavioral treatment of panic disorder: Clinical predictors and alternative strategies for assessment. J Consult Clin Psychol 1995;63:754–765. 9. Kite SM, Maher EJ, Anderson K, et al. Development of an aromatherapy service at a cancer centre. Palliat Med 1998;12:171–180. 10. Perry N, Perry E. Aromatherapy in the management of psychiatric disorders. CNS Drugs 2006;20:257–280. 11. Yim WC, Ng KZ, Tsang HWH, Leung AY. A review on the effects of aromatherapy for patients with depressive symptoms. J Altern Complement Med 2009;15:187–195. 12. Glasziou P, Irwig L, Bain CJ, Colditz G. Systematic Reviews in Health Care: A Practical Guide. UK: Cambridge University Press, 2001. 13. Hollis S, Campbell F. What is meant by intention to treat analysis? Survey of published randomised controlled trials. BMJ 1999;319:670–674. 14. Spatz C, Kardas EP. Research Methods in Psychology: Ideas, Techniques, and Reports. New York: McGraw-Hill, 2008. 15. Sjosten N, Kivel S. The effects of physical exercise on depressive symptoms among the aged: A systematic review. Int J Geriatr Psychiatry 2006;21:410–418. 16. Kyle G. Evaluating the effectiveness of aromatherapy in reducing levels of anxiety in palliative care patients: Results of a pilot study. Complement Ther Clin Pract 2006;12: 148–155. 17. Soden K, Vincent K, Craske S, et al. A randomized controlled trial of aromatherapy massage in a hospice setting. Palliat Med 2004;18:87–92. 18. Wilkinson S, Aldridge J, Salmon I, et al. An evaluation of aromatherapy massage in palliative care. Palliat Med 1999;13:409–417. 19. Burnett KM, Solterbeck LA, Strapp CM. Scent and mood state following an anxiety-provoking task. Psychol Rep 2004;95:702–722. 20. Kennedy DO, Little W, Haskell CF. Anxiolytic effects of a combination of Melissa officinalis and Valeriana officinalis during laboratory induced stress. Phytother Res 2006;20: 96–102. 21. Kutlu AK, Yilmaz E, Cecen D. Effects of aroma inhalation on examination anxiety. Teach Learn Nurs 2008;3:125–130. 22. Fujii M, Hatakeyama R, Fukuoka Y, et al. Lavender aroma therapy for behavioral and psychological symptoms in dementia patients. Geriatr Gerontol Int 2008;8:136–138. 23. Muzzarelli M, Force M, Sebold M. Aromatherapy and reducing preprocedural anxiety: A controlled prospective study. Gastroenterol Nurs 2006;29:466–471. 24. Lehrner J, Marwinski G, Lehr S, et al. Ambient odors of orange and lavender reduce anxiety and improve mood in a dental office. Physiol Behav 2005;86:92–95. 25. Graham PH, Browne L, Graham J. Inhalation aromatherapy during radiotherapy: Results of a placebo-controlled double-blind randomized trial. J Clin Oncol 2003;21:2372– 2376. 26. Wilkinson SM, Love SB, Westcombe AM, et al. Effectiveness of aromatherapy massage in the management of anxiety and depression in patients with cancer: A multiplecentre randomized controlled trial. J Clin Oncol 2007; 25:532–538. 27. Imura M, Misao H, Ushijima H. The psychological effects of aromatherapy-massage in healthy postpartum mothers. J Midwifery Womens Health 2006;51:21–26. 28. Stringer J, Swindell R, Dennis M. Massage in patients undergoing intensive chemotherapy reduces serum cortisol and prolactin. Psycho-Oncology 2008;17:1024–1031. 29. Burns EE, Blamey C, Ersser SJ. An investigation into the use of aromatherapy on intrapartum midwifery practice. J Altern Complement Med 2000;6:141–147. 30. Wiebe EE. A randomized trail of aromatherapy to reduce anxiety before abortion. Eff Clin Pract 2000;3:166–169. 31. Woelk H, Schla¨fke S. A multi-center, double-blind, randomised study of the lavender oil preparation silexan in comparison to lorazepam for generalized anxiety disorder. Phytomedicine 2010;17:94–99. 32. Hadfield N. The role of aromatherapy massage in reducing anxiety in patients with malignant brain tumors. Int J Palliat Nurs 2001;7:279–285. 33. Fountoulakis KN. Reliability and psychometric properties of the Greek translation of the state-trait anxiety inventory form Y: Preliminary data. Ann Gen Psychiatry 2006; 5:2. 34. Vizi ES. Handbook of Neurochemistry and Molecular Neurobiology. NewYork: Springer, 2008. ANXIOLYTIC EFFECTS OF AROMATHERAPY 107
108 LEE ET AL. 35.Lis-Balchin M,Hart S.Studies on the mode of action of the Address correspondence to: essential oil of lavender (Lavandula angustifolia P.Miller) Hector W.H.Tsang,PhD Phytother Res 1999;13:540-542. Neuropsychiatric Rehabilitation Laboratory 36.Umezu T.Behavioral effects of plant-derived essential oils in Department of Rehabilitation Sciences the geller type conflict test in mice.Ipn I Pharmacol The Hong Kong Polytechnic University 2000:83:150. Hung Hom,Hong Kong 37.Cooke B,Ernst E.Aromatherapy:A systematic review.Br Gen Pract2000:50:493-496. E-mail:rshtsang@inet.polyu.edu.hk
35. Lis-Balchin M, Hart S. Studies on the mode of action of the essential oil of lavender (Lavandula angustifolia P. Miller). Phytother Res 1999;13:540–542. 36. Umezu T. Behavioral effects of plant-derived essential oils in the geller type conflict test in mice. Jpn J Pharmacol 2000;83:150. 37. Cooke B, Ernst E. Aromatherapy: A systematic review. Br J Gen Pract 2000;50:493–496. Address correspondence to: Hector W.H. Tsang, PhD Neuropsychiatric Rehabilitation Laboratory Department of Rehabilitation Sciences The Hong Kong Polytechnic University Hung Hom, Hong Kong E-mail: rshtsang@inet.polyu.edu.hk 108 LEE ET AL
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This article has been cited by: 1. Somrudee Saiyudthong, Sirinun Pongmayteegul, Charles A. Marsden, Pansiri Phansuwan-Pujito. 2015. Anxiety-like behaviour and c-fos expression in rats that inhaled vetiver essential oil. Natural Product Research 1-4. [CrossRef] 2. Shing-Hong Liu, Da-Chuan Cheng, Jia-Jung Wang, Tzu-Hsin Lin, Kang-Ming Chang. 2015. Effects of Moderate Exercise on Relieving Mental Load of Elementary School Teachers. Evidence-Based Complementary and Alternative Medicine 2015, 1-8. [CrossRef] 3. Jane BuckleStress and Well-Being 223-237. [CrossRef] 4. Myung-Haeng Hur, Ji-Ah Song, Jeonghee Lee, Myeong Soo Lee. 2014. Aromatherapy for stress reduction in healthy adults: a systematic review and meta-analysis of randomized clinical trials. Maturitas 79, 362-369. [CrossRef] 5. Shingo Ueki, Kazuteru Niinomi, Yuko Takashima, Ryoko Kimura, Kazuyo Komai, Kiyotaka Murakami, Chieko Fujiwara. 2014. Effectiveness of aromatherapy in decreasing maternal anxiety for a sick child undergoing infusion in a paediatric clinic. Complementary Therapies in Medicine 22, 1019-1026. [CrossRef] 6. Robert Pellegrino, Philip G. Crandall, Corliss A. O’Bryan, Han-Seok Seo. 2014. A review of motivational models for improving hand hygiene among an increasingly diverse food service workforce. Food Control . [CrossRef] 7. Lillehei Angela S., Halcon Linda L.. 2014. A Systematic Review of the Effect of Inhaled Essential Oils on Sleep. The Journal of Alternative and Complementary Medicine 20:6, 441-451. [Abstract] [Full Text HTML] [Full Text PDF] [Full Text PDF with Links] 8. Susanna Stea, Alina Beraudi, Dalila De Pasquale. 2014. Essential Oils for Complementary Treatment of Surgical Patients: State of the Art. Evidence-Based Complementary and Alternative Medicine 2014, 1-6. [CrossRef] 9. Karsten Münstedt, Vivien Dütemeyer, Jutta Hübner. 2013. Patients’ considerations behind the use of methods from complementary and alternative medicine in the field of obstetrics in Germany. Archives of Gynecology and Obstetrics 288, 527-530. [CrossRef] 10. Linda L. HalcónAromatherapy in Pregnancy and Childbirth 173-195. [CrossRef] 11. Hector W. H. Tsang, Samuel C. L. Lo, Chetwyn C. H. Chan, Timothy Y. C. Ho, Kelvin M. T. Fung, Alan H. L. Chan, Doreen W. H. Au. 2013. Neurophysiological and behavioural effects of lavender oil in rats with experimentally induced anxiety. Flavour and Fragrance Journal 28:10.1002/ffj.v28.3, 168-173. [CrossRef] 12. Shing-Hong Liu, Tzu-Hsin Lin, Kang-Ming Chang. 2013. The Physical Effects of Aromatherapy in Alleviating Work-Related Stress on Elementary School Teachers in Taiwan. Evidence-Based Complementary and Alternative Medicine 2013, 1-7. [CrossRef] 13. Pam Conrad, Cindy Adams. 2012. The effects of clinical aromatherapy for anxiety and depression in the high risk postpartum woman – A pilot study. Complementary Therapies in Clinical Practice 18, 164-168. [CrossRef] 14. Jo Kamen KM Fung, Hector WH Tsang, Raymond CK Chung. 2012. A systematic review of the use of aromatherapy in treatment of behavioral problems in dementia. Geriatrics & Gerontology International no-no. [CrossRef] 15. J. Sarris, S. Moylan, D. A. Camfield, M. P. Pase, D. Mischoulon, M. Berk, F. N. Jacka, I. Schweitzer. 2012. Complementary Medicine, Exercise, Meditation, Diet, and Lifestyle Modification for Anxiety Disorders: A Review of Current Evidence. EvidenceBased Complementary and Alternative Medicine 2012, 1-20. [CrossRef] 16. Myeong Soo Lee, Jiae Choi, Paul Posadzki, Edzard Ernst. 2012. Aromatherapy for health care: An overview of systematic reviews. Maturitas . [CrossRef] 17. Ling Jun Kong, Min Fang, Hong Sheng Zhan, Wei An Yuan, Ji Ming Tao, Gao Wei Qi, Ying Wu Cheng. 2012. Chinese Massage Combined with Herbal Ointment for Athletes with Nonspecific Low Back Pain: A Randomized Controlled Trial. Evidence-Based Complementary and Alternative Medicine 2012, 1-8. [CrossRef] 18. Xiongzhao Zhu, Min Peng, Ming Cheng, Xianzhong Xiao, Jingyao Yi, Shuqiao Yao, Xiuwu Zhang. 2011. Hyperthermia protects mice against chronic unpredictable stress-induced anxiety-like behaviour and hippocampal CA3 cell apoptosis. International Journal of Hyperthermia 27, 573-581. [CrossRef]
