Self-reported depressive syndromes in mild cognitive impairment and mild Alzheimer's disease

Abstract

There is suggestion that self-reported depressive syndromes can independently manifest in the general population as cognitive/affective or somatic/vegetative. The Beck Depression Inventory, 2nd edition (BDI-II), a self-report measure of depressive symptoms, has been shown to support this two-factor structure. However, this finding has not been examined in an older adult sample with cognitive impairment. In order to determine whether older adults with cognitive impairments exhibit similarly independent cognitive/affective and somatic/vegetative depressive syndromes, we explored the factor structure of the BDI-II in this population. Participants were 228 older adults (mean age = 74, SD = 7.9) diagnosed with mild cognitive impairment (MCI; n = 137) or early Alzheimer's disease (n = 85), who completed the BDI-II as part of an outpatient neuropsychological evaluation. Exploratory principal component factor analysis with direct Oblimin rotation was conducted, and a two-factor solution was specified based on our theoretical conceptualization of the cognitive/affective and somatic/vegetative items from the scale. The first factor represented cognitive/affective symptoms of depression (e.g. self-dislike, pessimism, worthlessness), and accounted for 36% of the variance. Adding the second factor, reflecting somatic/vegetative items (e.g. sleep and appetite changes, loss of energy), accounted for an additional 6.8% of the variance. Results supported the presence of two distinct depressive syndromes, cognitive/affective and somatic/vegetative symptoms. Thus, cognitively impaired older adults report mood symptoms relatively similarly to younger and midlife adults. This supports the validity of self-reported mood in this group, and the results may have implications for psychiatric treatment in this population.