Olfactory dysfunction discriminates probable Alzheimer's dementia from major depression: A cross-validation and extension

The present study was conducted to cross-validate and extend the hypothesis that olfactory dysfunction could discriminate between groups of patients w ith Alzheimer's disease and major depression. Forty patients meeting the DS M-IV criteria for either Alzheimer's disease or major depression (20 per gr oup) underwent assessment with the Pocket Smell Test (PST), it three-item s creening measure of odor identification, and the Mini-Mental State Examinat ion (MMSE). A PST score of less than or equal to 1 (1 or 0 correct) discrim inated between the groups with a hit rate of 97.5% (sensitivity = 95%, spec ificity = 100%). The optimal hit rate for the MMSE (less than or equal to 2 4) was less effective (hit rate = 90%, sensitivity = 80%, specificity = 100 %). Age, gender, and education had minimal impact on the PST for both group s. Olfactory assessment continues to add to the diagnostic utility in the d ifferential diagnosis of Alzheimer's disease versus major depression in eld erly patients.