Table 1.
Overview of study characteristics.
| References and country | Study design | Participants | Setting | Study aims | Intervention procedure | Measures | |
|---|---|---|---|---|---|---|---|
| N | Mean/range age | ||||||
| Lopis et al., (2021), F | Quasi-experimental (non-randomised design; between-subject design) | 180 60 PwD r 60 HoP n 60 young adult Mild AD a |
80.9 ± 6.2 (exp) control: 80.1 ± 6.2 HoPn 22.2 ± 2.9 young adult | - | Assess the frequency and phenomenological characteristics (emotional valence, emotional intensity, memory vividness and rarity) of odour-evoked autobiographic memories compared those recalled by visual and auditory cues | Participants were asked to recall memories after presenting and labelling either 4 odours, 4 sounds (i.e. cutting bread, crunching apple, wood crackling and wine bottle opening), or 4 pictures (French bread, apple, a wood fire, wine bottle) | MMSE o ; Frontal Assessment Battery; verbal fluency task; episodic memory with 5-word test; forward and backward digit spans; 15-item Geriatric Depression Scale; The Mini International Psychiatric Interview 5.0.0; Likert scales for assessing emotional valence, emotional intensity, vividness and rarity of the memory as well as stimuli property (intensity; stimulus-reality; pleasantness) |
| Glachet & El Haj (2020a), F | Quasi-experimental (non-randomised design) | 49 24 PwD r (exp.) 25 HoP n (control) Mild AD a |
85.12 ± 5.68 (exp) 84 ± 8.5 (control) |
- | Investigate the phenomenological characteristics (specificity, arousal and emotional valence) and retrieval time of past events and future thinking | Participants retrieved 1 past and 1 future event for 2 minutes in a free-odour condition and after odour exposure. The sessions were counterbalanced and 1 week apart | MMSE o ; Grober and Buschke’s task; Geriatric Depression Scale; SAM s ; TEMPau v ; reaction time between the end of the instruction and the beginning of the narrative |
| Glachet & El Haj (2020b), F | Quasi-experimental (non-randomised design) | 49 24 PwD r (exp.) 25 HoP n (control) Mild AD a |
85.12 ± 5.68 (exp) 84 ± 8.5 (control) |
- | Investigate the effects of odour exposure on access to self-concept (i.e. psychological self, physical self or social self) | Participants produced self-related statements of their identity (including roles, personality traits or physical traits) within 1 min following odour and odour-free exposure. The sessions were counterbalanced and 1 week apart | MMSE o ; Grober and Buschke’s task; Geriatric Depression Scale; span task (forward and backward span) SAM s ; phonemic and semantic fluency tasks; total number of self-related statements (i.e. psychological self, social self and physical self-statements) |
| Takahashiet al. (2020), JAP | Experimental (single-blind randomised controlled) | 36 Mild-moderate AD a Care staff |
76.2 ± 9.8 (exp) 75.8 ± 7.8 (control) |
- | Evaluate the effects of ethanol with and without aroma extracts on caregiver burden, residents' responsive behaviours and cognitive function | Exp. group was exposed to ethanol with cedar scent diffused in the living room and bedroom and sprayed into clothing and bedding a few times a day over an 8-week period. The control was exposed to ethanol without cedar scent. Effects were tested pre-intervention, after 4 weeks and post-intervention | OSIT-J q ; NPI p ; ZBI-J x ; ADAS-cog b |
| Glachet et al. (2019), F | Quasi-experimental (non-randomised design; within-subject design) | 54 26 PwD r (exp.) 28 HoP n (control) Mild AD a |
72.69 (exp) 70.82 (control) |
- | Assess the effect of odour exposure on the retrieval of recent and remote memories | Participants recalled two autobiographical memories related to childhood, adulthood and last 5 years in 1 free-odour and 1 odour (i.e. coffee) session | MMSE o ; Grober and Buschke’s task; span tasks; HAD l ; TEMPau v |
| Glachet & El Haj (2019), F | Quasi-experimental (non-randomised design) | 48 25 PwD r (exp.) 23 HoP n (control) Mild AD a |
82.04 ± 7.34 (exp); 80.91 ± 9.87 (control) | - | Explore the impact of olfactory cueing on
autobiographic memories (i.e. arousal, emotional valence, subjective reliving and specificity) and its relationship with depression |
Participants recalled autobiographical memories in 1 free-odour and 1 odour session | MMSE o ; HAD l ; SAM s ; Grober and Buschke’s task; subject reliving; TEMPau v |
| El Haj et al. (2018), F | Quasi-experimental (non-randomised design) | 58 28 PwD r (exp.) 30 HoP n (control) Mild AD a |
73.25 ± 6.71 (exp) 71.75 ± 8.05 (control) |
- | Compare the specificity, emotion, retrieval time of odour-, music-evoked and no sensory cueing autobiographical memories | Participants recounted 2 personal events for 3 minutes after 1 odour exposure, 1 music exposure and 1 control session. Between the two retrievals, an executive task was performed (i.e. odour-verbal fluency; music- plus–minus task; control condition-Stroop task). The sessions were counterbalanced with a 3- to 5-day interval between sessions | MMSE o ; Grober and Buschke’s task; HAD l ; executive function: Verbal fluency task, the plus–minus task, Stroop task; TEMPaus v ; emotion and mental time travel rate Likert-scale; reaction time between the end of the instruction and the start of memory generation |
| Sulmont-Rossé et al. (2018), F | Quasi-experimental (non-randomised crossover design) | 32 Moderate to severe AD a |
86.8 mean 75-98 range |
Nursing home | Evaluate the impact of olfactory priming in food intake and eating behaviours | Participants took part in a total of (alternated) 2 control lunches and 2 primed lunches, every 2 weeks. Room odourisation started 15 min before lunch and ended before serving the main course | MMSE o ; food intake: Weighing plates before and after consumption; proxy observation of resident’s behaviours during lunch time (attention to care staff, to dish and meal tray before lunch; appetite; sit at the table) |
| Moorman Li et al. (2017), US | Quasi-experimental (pre- and post-design) | 23 |
83 mean 73–97 range |
Adult day care centre |
Evaluate the effects of aromatherapy on responsive behaviours (i.e. restlessness/wandering, agitation, anger and anxiety) and comparison of age cohorts, gender and individual behaviour frequency | Lavender oil was diffused in a room for 20 min twice a day (morning and mid-afternoon) for 2 months. Pre- (a 2-months) and post-intervention observation were conducted | Behaviour/intervention monthly
flow record observation pre- and post-intervention |
| Takeda et al. (2017), JAP | Quasi-experimental (non-randomised crossover design) | 19 Severe dementia |
80.7 ± 9.1 | Nursing home | Evaluate the effects of aromatherapy on symptoms of sleep disturbance | The residents’ pillows were wrapped for 20 days with a towel with no odour, followed by 20 days with a scented towel during the night | MMSE
o
; FIM
i
; times of going to bed and rising; NPI
p
; 24 h sheet-type body vibrometer; sleep
disturbance: (1) difficulty initiating sleep; (2) difficulty maintaining sleep; (3) early morning awakening and (4) daytime disorder |
| Fu et al. (2013), AU | Experimental (single-blind randomised controlled) | 67 9 mild 23 moderate 29 severe 29 dementia 16 AD a 3 VaD w 8 cognitive impairment (no diagnosis) 5 other dementia |
84 ± 6.36 61–93 range |
Long-term care facilities | Compare the effect of aromatherapy (oil spray), placebo (water spray) and a combination of aromatherapy and hand massage to reduce responsive behaviours, particularly aggression and agitation | 3 groups received a combination of aromatherapy and hand massage, or aromatherapy (lavender spray on the upper chest), or placebo control (water spray on the upper chest), twice a day (9–11 a.m.; 2–4 p.m.) 7 days a week for 6 weeks. Hand massage duration: 5 min (2.5 min for each hand). Evaluation occurred at 5 points time (baseline, week 2-4–6, post-test) | MMSE o ; CMAI-SF d |
| Sakamatoet al. (2012), JAP | Experimental (double-blind randomised controlled) | 145 72 (exp) 73 (control) Moderate dementia |
84.2 ± 7.8 (exp) 84.1 ± 7.7 (control) |
Nursing homes | Investigate the effects of lavender on fall incidence in nursing home residents | 24 h olfactory stimulation from a lavender patch attached to the inside of the resident’s clothes near the neck for 360 days | Number of resident falls; Barthel Index; Vital Index; St. Thomas’s Risk Assessment Tool in Falling Elderly Inpatients; MMSE o ; CMAI c |
| Jimbo et al. (2009), JAP | Quasi-experimental (non-randomised crossover design) | 28 PwD
r
21 care staff 9 mild to moderate 19 Severe 17 AD a 3 VaD w 8 other dementia |
86.1 ± 6.9 | - | Assess the effect of aromatherapy on cognitive function | Participant received aromatherapy in two different rooms in the morning and evening for 28 days. The intervention was preceded by a control period of 28 days and followed by a 28-days wash out period. During the control and wash up period, participants did not receive any intervention. Assessment at four points: Before control condition, before and after aromatherapy and after a wash out period | GBSS-J
k
; TDAS
u
FAST h ; HDS-R m ; head computed tomography; blood analysis and biochemical examination; ZBI-J x |
| Lin et al. (2007), JAP | Experimental (crossover randomised design) |
70 Moderate to severe 44 AD a 21 VaD w 5 other dementia |
78.29 ± 4.06 69–89 range |
Care homes | Compare the effect of lavender aromatherapy with a control condition (sunflower odour) | Each participant received both conditions. Both conditions lasted for 3 weeks and were 2 weeks apart. At least 1 h of exposure to odour during sleep time at night. Evaluation occurred pre- (0 week), post-intervention (week 3) and pre- (week 5), post-control condition (week 8) | CMAI
c
Chinese version; CNPI
f
CMMSE e |
| Snow et al. (2004), US | Quasi experimental (non-randomised crossover design) | 7 Severe dementia AD a |
- | Nursing home | Investigate effects of an essential oil on the frequency of agitated behaviours; participants’ olfactory functions | Each participant had an absorbent fabric sachet with aroma [lavender (A) and thyme (B)] and no aroma oil [unscented grapeseed C)] pinned to their shirt near the collarbone every 3-h, for a total of 3 applications per day, over 2 weeks for each condition (total of 10 weeks). The condition followed ABCBA order | CMAI c ; SIRS t ; olfactory functioning: Identification (sniff and name task), discrimination (2-odours discrimination task); participants’ reactions (recorded verbatim in the above two tasks) |
| Holmes et al. (2002), UK | Quasi-experimental (non-randomised crossover design) | 15 Severe dementia 4 AD a 7 VaD w 3 DLB g 1 FTD j |
79 ± 6.3 | Long-term care facility | Evaluate the effect of aromatherapy steam on agitated behaviour | Each participant was exposed for 2h (4–6 p.m.) in a communal area to a total of 5 odour and 5 placebo (water) sessions on alternate days, over a period of 2 weeks | Pittsburgh Agitation Scale |
| Gray & Clair (2002), US | Quasi-experimental (non-randomised crossover design) | 13 |
- | Care homes | Examine the effects of aromatherapy on the administration of medications (i.e. frequencies of resistive behaviours, time of administer medications, gender difference for frequency and time-administration) | Twenty minutes before early morning medication administration, a cotton ball with essential oil (lavender vera, sweet orange or tea tree) or without aroma (control) was taped to the lapel of each participant. Each of the four conditions was repeated in a random order four times for a total of 16 administrations | Video records for the duration of the medication administration |
| Smallwood et al. (2001), UK | Experimental design (single-blind randomised control design) | 21 Severe dementia |
66.8 ± 11.5 | Hospital | Compare the impact of aromatherapy massage, plain oil massage and aromatherapy and conversation on responsive behaviours | Participants were randomly allocated in aromatherapy massage, or massage or aromatherapy intervention provided twice weekly | 15 minutes video records in 4 times a day (10–11 a.m., 11–12 noon, 2–3 p.m. and 3–4 p.m.) twice during 2-weeks at the baseline. Participants’ behaviours were recorded after receiving intervention |
| Brooker et al. (1997), UK | Single case study | 4 Severe dementia 2 AD a 1 AD a and Parkinson 1 FTDj |
74–91 range | Hospital | Evaluate the impact of aromatherapy, aromatherapy massage, massage only and no treatment on agitation | Each participant randomly received between 8 and 12 sessions of each four conditions (lavender oil delivered via fan; lavender and massage; massage; no treatment) over a 3-month period. Each session lasted 30 minutes | Agitation observation scale 1 h after intervention, rated at 1 minute intervals |
| Henry et al. (1994), UK | Quasi experimental (pre- and post-design) | 9 Severe dementia - |
- | Hospital | Assess the effect of aromatherapy on the number of night time hours spent asleep | Each participant was exposed to lavender aromatherapy in the bedroom during the night. Over a 7-week period: 2 weeks sleep observation; the third week the lavender was diffused only in the female dormitory; the fourth week only in the male dormitory; the final 3 weeks in both dormitories | Tot. hour sleep: Sleep observation between 12 a.m. to 7.30 a.m. at half hourly intervals |
aAD = Alzheimer’s Disease.
bADAS-cog = Alzheimer’s Disease Assessment Scale-Cognitive Subscale.
cCMAI = Cohen-Mansfield Agitation Inventory.
dCMAI-SF = Cohen-Mansfield Agitation Inventory Short Form.
eCMMSE = Mini-Mental State Examination Chinese version.
fCNPI = Neuropsychiatric Inventory Chinese version.
gDLB = Dementia Lewy Body.
hFAST = Functional Assessment Staging Test.
iFIM = Functional Independence Measure.
jFTD = Frontotemporal dementia.
kGBSS-J = The Gottfries, Bråne, Steen Scale.
lHAD = Hospital Anxiety and Depression Scale.
mHDS-R = Hasegawa’s dementia scale.
nHoP = Healthy older People.
oMMSE = Mini-Mental State Examination.
pNPI = Neuropsychiatric Inventor.
qOSIT-J = Odor Stick Identification Test for Japanese.
rPwD = People with Dementia.
sSAM = Self-Assessment Manikin.
tSIRS = Severe Impairment Rating Scale.
uTDAS = Touch-panel type Dementia Assessment Scale.
vTEMPau = Test Episodic de Mémoire du Passé.
wVaD = Vascular dementia.
xZBI-J = Zarit Caregiver Burden Interview Japanese version.