Effects of olfactory stimulation on cognitive function and behavior problems in older adults with dementia: A systematic literature review.

The aim of this study was to examine the effects of olfactory stimulation on both cognitive and behavioral symptoms in neurodegenerative diseases. The criteria for selection of participants in the study included neurodegenerative disease, interventions using olfactory stimulation, and measured cognitive or psychological symptoms. 5301 articles were identified, excluding duplicate papers. Seven original articles were selected according to the full article review and eligibility criteria. The final selected studies were all quasi-experimental studies and were published between 2002 and 2015. To assess the risk of bias, we used Cochrane Collaboration's tool, Non-randomized Studies-of Interventions (ROBINS-I). Although olfactory stimulation reported various effects on behavioral and psychological symptoms, it is still in its infancy. We propose standardization of olfactory stimulation and olfactory training. In patients with neurodegenerative diseases, it is necessary to consider the symptoms and severity of olfactory stimulation.