The specificity of depressive symptoms in patients with Alzheimer's disease

Objective: This study assessed the specificity of depressive symptoms in patients with Alzheimer's disease and examined the discrepancies between patient and caregiver symptom reports. Method: The study group was composed of a series of 233 patients with Alzheimer's disease, 47 patients with depression but without dementia, and 20 healthy comparison subjects; the latter two groups were comparable in age with the patients with Alzheimer's disease. The patients and comparison subjects received a comprehensive psychiatric evaluation, which included administration of the Hamilton Depression Rating Scale and the Structured Clinical Interview for DSM-IV. Results: Patients with Alzheimer's disease with a score of 2 or higher on the "depressed mood" item of the Hamilton depression scale, as scored by their respective caregivers, comprised a group with depressed mood (N=92), whereas patients who scored 0 on this item comprised a group without depressed mood (N=62). A statistical comparison of the scores on the remaining Hamilton depression scale items (2-16) between the Alzheimer's disease patients with and without depressed mood revealed significant differences on all items, except "loss of appetite." However, there were no significant differences on any single Hamilton depression scale item between the Alzheimer's disease patients without depressed mood and the age-comparable healthy comparison subjects. Conclusions: Depressive symptoms are not widespread among patients with Alzheimer's disease but are significantly related to an underlying depressed mood. Patients with Alzheimer's disease may not be fully aware of the extent of their depressive symptoms.