Olfactory deficits in Down subjects: a link with Alzheimer disease.

Two groups of subjects, 14 young (ages 20 to 31 years) and 14 adults (ages 32 to 54 years), both groups with Down Syndrome, were examined on a matching and naming olfactory task. On the former, subjects were required to recognize among four a previously sniffed odour, while on the latter they had to label an odour by choosing among four alternatives provided by the examiner. Analysis indicated that the adults with Down Syndrome scored worse than the young group on both tasks and that the impairment of the two groups was more pronounced on the matching task. On considering the similarity between the neurodegenerative brain pathology exhibited by Alzheimer patients and Down subjects and a recent observation that the former show pathological changes also in the olfactory epithelium (neuritic plaques and neurofibrillary tangles), these two olfactory tasks could represent a useful noninvasive diagnostic method.