The Impact of Depressive Symptoms on Patients With Alzheimer Disease

Depression commonly accompanies Alzheimer disease (AD), but its optimal definition, impact on cognition and function, natural history after onset of AD, and risk factors for its occurrence are ill understood. Garre-Olmo et al. (2003) provide important insights into the relationship of AD and depression in their article in the current issue of this Journal. The investigators report on 150 patients who were examined at baseline and were available after 1 year for reassessment. The patient group is reasonably typical of AD clinical cohorts with mean Mini-Mental State Examination Scores of 15.9 mean age of 75.4 years, and sex distribution of 70% women. Educational level was somewhat lower than many previous study samples (average number of years of education was 5.6). Standard research criteria were used for diagnosis of AD. Patients were assessed at two time points with the Neuropsychiatric Inventory (NPI) (Cummings et al., 1994). Four patient groups were evident: (1) those with depression at both time points (persistent mood changes), (2) those who were depressed at baseline but not after 1 year (resolving depression), (3) those who were not depressed at baseline but became depressed in the ensuing year (emergent depression), and (4) those who were without mood changes at either assessment. For this study, depression was defined as any score on the Depression/Dysphoria subscale of the NPI. This is a low threshold for identifying depression and differs from that applied to most studies of depression in AD. The study may be interpreted as addressing the impact of depressive symptoms on AD rather than an investigation of “depression” in AD (a terminology usually applied to the diagnosis of major or minor depression). The researchers found that 51% of AD patients were depressed at the time of first assessment, a relatively higher value than reported in many recent studies and likely reflecting the low threshold for identifying depression. Of these, 55% had persistent depression and exhibited mood changes at baseline and after 1 year (conversely, 45% had resolution of their depression); 20% of patients had emergent depression, evidencing mood changes on the second assessment but not at study onset. Depression at baseline was associated with more nonmood symptoms, greater functional deficits, and history of a psychiatric disorder. Persistence of depression was predicted by a larger number of depressive symptoms at baseline (as determined by the number of symptoms elicited on the NPI). Caregivers also reported higher frequencies (occurring more often in the month prior to assessment) of depressive symptoms at baseline in those with persistent symptoms. Patients whose symptoms resolved during the observation period had fewer depressive symptoms at baseline and were less likely to have a history of a psychiatric disorder. Resolution of mood changes was associated with a decrease in the number of non-mood behavioral symptoms and a slight improvement in functional capacity. Emergence of depressive symptoms was more likely in those with a past psychiatric disorder. Logistic regression identified the number of depressive symptoms at baseline and a history of a psychiatric disorder as the best predictors of mood state after 12 months, predicting 72% of the cases with depressive symptoms. These are important new data and help to inform our understanding of the relationship of mood changes to AD. This is among the first studies to address which clinical features are associated with persistence of depression. The observation that higher frequencies of Received March 24, 2003. Accepted March 27, 2003. Address correspondence and reprint requests to Jeffrey Cummings, M.D., Reed Neurological Research Center 2-238, UCLA Alzheimer’s Disease Center, 710 Westwood Plaza, Los Angeles, CA 90095-1769, U.S.A. E-mail: cummings@ucla.edu Alzheimer Disease and Associated Disorders Vol. 17, No. 2, pp. 61–62 © 2003 Lippincott Williams & Wilkins, Inc., Philadelphia