Can olfactory training support improvement of cognitive functioning in patients with mild cognitive impairment?

Abstract

Aim. According to some theoretical interpretations of the olfactory training effects, the training may indirectly exert positive influence on cognitive functioning in patients with Alzheimer's dementia. The mechanism of action is stimulation of cerebral blood flow in areas of brain which are shared by olfactory and memory processes. The aim of this article is to verify a hypothesis that the olfactory training improves memory and attention functions in patients with amnestic mild cognitive impairment. Method. Participants with amnestic mild cognitive impairment (N = 35; 17 males and 18 females) constituted their own control group. During the first 12 weeks from the baseline evaluation no therapeutic actions were performed. The subjects underwent control neuropsychological assessment and entered in the second stage of the study. In that stage they were subjected to a daily olfactory training, which included two a few-minute-long sessions per day, which were performed for the following 3 months. Subject's memory functioning was measured at three time points: at the baseline, after 3 months and after 6 months (from the baseline). Cross-over assignment was used as the intervention method - which means that the participants constituted their own control group. The scales employed in the study to measure memory and attention were: ACE-III, CVLT, and MMSE. Results. Statistically significant improvement in memory functions measured with the CVLT, MMSE, ACE-III Memory, and ACE-III Total Score was obtained. It is considered an artefact related to practice effects, not true training results. Moreover, trend suggesting improvement on the ACE-III Attention was noted as well. Conclusions. The authors review theoretical implications of the conducted study. Methodological challenges pertaining to the study design are discussed and future research directions are proposed.