Taste, smell and neuropsychological performance of individuals at familial risk for Alzheimer's disease

The purpose of the study was to determine whether there are chemosensory and neuropsychological changes that predate the onset of Alzheimer's disease in individuals at enhanced risk of developing the condition. To study this question, a unique sample of individuals (n = 33) was studied who were genetically at-risk for AD by virtue of documented multigenerational evidence of the disease (so-called multiplex families). The performance of at-risk individuals was evaluated on various smell, taste, and neuropsychological measures at baseline and 18 months later. Their performance was compared to a control group (n = 32) that was matched in age, gender, education, and race. At baseline the at-risk group performed worse than the control group on the chemosensory measures of phenethyl alcohol smell detection, smell memory, and taste memory, and on a memory measure involving recall of narrative information (Logical Memory I from the Wechsler Memory Scale- Revised). Across both sessions, the at-risk group had lower smell memory scores than the control group. At-risk status was not significantly associated with APOE status. The results of this and other studies suggest that individuals who are genetically at risk for developing AD may perform more poorly on memory and smell measures compared to those not at risk. This effect may be separate from one known genetic risk factor of AD, APOE, and supports that multiple genes are likely responsible for the disease and its associated memory and other neurocognitive symptoms.