Investigating the effects of reminiscence using smells on loneliness and depressive symptoms in community-dwelling older adults: a randomised controlled trial.

Background: The use of a variety of sensory elements is recommended when implementing reminiscence therapy. However, there is a lack of evidence supporting this recommendation. This study aimed to examine the benefits of using smell as a memory trigger during reminiscence therapy for community-dwelling older adults, focusing on its effects on loneliness and depressive symptoms.

Methods: Seventy-nine community-dwelling older adults were randomly allocated to either an intervention or a control group. Participants in the intervention group underwent a total of eight 40-min. reminiscence therapy sessions once a week that used smell as a trigger. The control group underwent similar reminiscence therapy but only used themed conversations. Their responses were assessed pre- and post-intervention using the UCLA Loneliness Scale version 3 (UCLA LS3), which evaluates loneliness, and the Geriatric Depression Scale-15-Japanese, which measures the state of depressive symptoms.

Results: The pre-intervention comparison of the participants' characteristics and each evaluation item showed significant differences (P = 0.030) between the two groups' olfactory visual analogue scale (VAS) scores. Subsequently, we performed analysis of covariance via repeated measurements, using olfactory VAS as the covariate, and found significant interactions in UCLA LS3 (P = 0.006) alone. To identify items for consideration during interventions, we examined factors related to post-intervention UCLA LS3 scores. Our results showed that the notion of usefulness, by which participants perceived the smell triggers to be useful for inducing reminiscence (P = 0.045), was significantly related to pre-intervention UCLA LS3 scores (P < 0.001) in the intervention group.

Conclusion: These findings show that using smell as a trigger during reminiscence therapy can effectively alleviate loneliness and suggest the need to prepare appropriate odorants for facilitating reminiscence.