This Cochrane review assessed the efficacy and safety of aromatherapy for people with dementia. The researchers included randomised controlled trials which compared fragrance from plants in an intervention defined as aromatherapy for people with dementia with placebo aromatherapy or with treatment as usual. All doses, frequencies and fragrances of aromatherapy were considered. Participants in the included studies had a diagnosis of dementia of any subtype and severity.
The investigators included 13 studies with 708 participants. All participants had dementia and in the 12 trials which described the setting, all were resident in institutional care facilities. Nine trials recruited participants because they had significant agitation or other behavioural and psychological symptoms in dementia (BPSD) at baseline. The fragrances used were:
- lavender (eight studies);
- lemon balm (four studies);
- lavender and lemon balm,
- lavender and orange,
- cedar extracts (one study each).
For six trials, assessment of risk of bias and extraction of results was hampered by poor reporting. Four of the other seven trials were at low risk of bias in all domains, but all were small (range 18 to 186 participants; median 66). The primary outcomes were:
- overall behavioural,
- psychological symptoms,
- adverse effects.
Ten trials assessed agitation using various scales. Among the 5 trials for which the confidence in the results was moderate or low, 4 trials reported no significant effect on agitation and one trial reported a significant benefit of aromatherapy. The other 5 trials either reported no useable data or the confidence in the results was very low. Eight trials assessed overall BPSD using the Neuropsychiatric Inventory and there was moderate or low confidence in the results of 5 of them. Of these, 4 reported significant benefit from aromatherapy and one reported no significant effect.
Adverse events were poorly reported or not reported at all in most trials. No more than two trials assessed each of our secondary outcomes of quality of life, mood, sleep, activities of daily living, caregiver burden. There was no evidence of benefit on these outcomes. Three trials assessed cognition: one did not report any data and the other two trials reported no significant effect of aromatherapy on cognition. The confidence in the results of these studies was low.
The authors reached the following conclusions: We have not found any convincing evidence that aromatherapy (or exposure to fragrant plant oils) is beneficial for people with dementia although there are many limitations to the data. Conduct or reporting problems in half of the included studies meant that they could not contribute to the conclusions. Results from the other studies were inconsistent. Harms were very poorly reported in the included studies. In order for clear conclusions to be drawn, better design and reporting and consistency of outcome measurement in future trials would be needed.
This is a thorough review. It makes many of the points that I so often make regarding SCAM research:
- too many of the primary studies are badly designed;
- too many of the primary studies are too small;
- too many of the primary studies are poorly reported;
- too many of the primary studies fail to mention adverse effects thus violating research ethics;
- too many of the primary studies are done by pseudo-scientists who use research for promotion rather than testing hypotheses.
It is time that SCAM researchers, ethic review boards, funders, editors and journal reviewers take these points into serious consideration – if only to avoid clinical research getting a bad reputation and losing the support of patients without which it cannot exist.