Whether depression increases risk of dementia or is a symptom of cognitive decline remains an area of active investigation. While some findings have suggested that older adults develop depression in response to the experience of cognitive decline, others have pointed to depression as a risk factor for cognitive decline. Most of these studies, however, assessed the depressive symptoms of older adults at a single point in time, limiting the ability of researchers to capture symptom variability within individual patients or the longitudinal course of depression.
In the current study, Allison Kaup, Ph.D., an assistant professor of psychiatry at the University of California, San Francisco, and colleagues evaluated whether the depressive symptom trajectories of 2,488 older adults captured over a five-year period (1997-1998 through 2001-2002) were associated with the development of dementia at follow-up six years later (2007-2008). Depressive symptoms were measured using the Center for Epidemiologic Studies Depression Scale Short Form at years 1, 3, 4, and 5 of the study. Incident dementia was determined based on hospital records, medication use, and decline in global cognitive functioning.
Overall, 353 participants (14.2%) developed dementia over the course of the follow-up period and did so a mean of 3.9 years after the depressive symptom assessment period. Compared with individuals with consistently minimal depressive symptoms, those with high and increasing symptoms were significantly more likely to develop dementia.
“Whether depression is a risk factor for dementia versus a symptom of an underlying neurodegenerative process is a complex question. Although our study cannot fully disentangle these possibilities, our results suggest the nature of the depression-dementia relationship may differ depending on the pattern of depressive symptoms,” the authors wrote. “Our results suggest that individuals’ trajectory of depressive symptoms may inform dementia risk above and beyond assessment of depressive symptoms at one time point alone.”
For related news, see the Psychiatric News article “Older Adults With Depression, Cognitive Impairment May Benefit From Psychosocial Therapy.”
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