THE STUDY by Bassuk et al1 adds to an expanding literature assessing whether depression is a risk factor for new-onset dementia or whether relationships are cross-sectional rather than predictive; the former would indicate depression as prodromal and the latter as a clinical concomitant disorder. In their analysis of prospective epidemiological data, Bassuk and colleagues found high scores (≥16) on the Center for Epidemiological Studies Depression Scale (CES-D)2 to predict subsequent cognitive decline, but only in persons exhibiting mild baseline impairment. Thus, depression seemed to be an early feature of a progressive disorder but not a risk factor for incident dementia. The concomitant feature argument is strengthened by the close temporal association between achieving the CES-D cutoff and demonstration of cognitive decline.
Meyers BS, Bruce ML. The Depression-Dementia ConundrumIntegrating Clinical and Epidemiological Perspectives. Arch Gen Psychiatry. 1998;55(12):1082-1083. doi:10.1001/archpsyc.55.12.1082