Odour recognition memory and Odour identification in normal elderly and Alzheimer’s disease patients

Olfactory dysfunctions have been frequently observed in ageing, in various neurodegenerative conditions and in psy- chiatric disorders. Notably olfactory impairments that accompany or precede the early stage of Alzheimer’s disease may be seen as first clinical biomarkers of the pathology and predictors of the it’s progression. Methods: The present study evaluated odour recognition memory and odour identification in two groups of 12 mild Alzheimer’s disease patients (M age 64.4 years, range 61 - 77), 12 moderate Alzheimer’s disease patients (M age 67.2 years, range, 62 - 69), 12 Elderly (Elderly 1 group, M age 65.3 years, range, 60 - 68) and 12 very Elderly (Elderly 2 group, age 75.3, years, range, 70 - 83) with the aim to test whether in the Alzheimer’s disease individuals olfactory deficits do occur already at an early stage and increase in function of the disease severity and to examine the influence of ageing on the olfactory efficiency. We were also interested to test, beside the documented impairment in the identification of odours in neurodegenerative diseases and old people, the extent to which the less investigated odour memory was also impaired. Results: Data analyses showed that moderate Alzheimer’ disease patients performed significantly worse than Mild ones on both tasks and that a similar outcome was observed for the elderly (with the older group of Elderly performing worse than the younger). Conclusions: The present results highlight the presence in Alzheimer’s disease patients of early and progressive olfactory dysfunc- tions and the role of the two olfactory tasks as useful instruments to discriminate between patients characterized by different levels of severity; they also confirm the available data from the literature showing a decrease in olfactory performance in the elderly population beyond the age of 60-65 years.