Depressive symptom patterns in patients with Parkinson's disease and other older adults.

Research on depression in Parkinson's disease (PD) has suggested that PD patients experience a qualitatively different depression from that of other older adults, endorsing fewer cognitive symptoms of depression (e.g., guilt, failure) and greater somatic (e.g., poor sleep) and mood symptoms (e.g., sadness, hopelessness); however, this has never been tested directly. In the present study, two PD groups, one with cognitive impairment (PD + CI; n = 26) and one without cognitive impairment (PD; n = 45), and three control groups of older adults were compared on measures of depressive symptomatology. The control groups included a physically disabled group (n = 46), a cognitively impaired group (CI; n = 21), and a healthy group (n = 50). Confirmatory factor analysis verified a four-factor model of depressive symptoms (Cognitive, Mood, Somatic, and Fatigue symptoms). Comparisons revealed that the PD group had a depressive-symptom pattern that was not significantly different from the disabled and healthy groups. The PD + CI group had a symptom pattern that was more similar to the CI group than to the PD group. Implications for the conceptualization of depression in older adults are discussed.