title: Apathy and depression: separate factors in Parkinson's disease.
abstract: The objective of this study was to test the hypothesis that apathy and depression are dissociable in Parkinson disease (PD) by conducting a confirmatory factor analysis (CFA) of items from two commonly used mood scales. A total of 161 non-demented PD patients (age = 64.1; ± 8.4 years) were administered the Apathy Scale and the Beck Depression Inventory-II. Items were hypothesized to load onto four factors: (1) an apathy factor representing loss of motivation, (2) dysphoric mood factor representing sadness and negativity, (3) loss of interest/pleasure factor representing the features common to both apathy and depression, and (4) a somatic factor representing bodily complaints. Results indicated a good fit for the overall CFA model, χ² (128, N = 146) = 194.9; p<.01. RMSEA was .060 (p = .16). The four-factor model was significantly better than all alternative nested models at p < .001, including an overarching single factor model, representing "depression." Results support the concept that apathy and depression are discrete constructs. We suggest a "factor based" scoring of the Apathy Scale and Beck Depression Inventory-II that disentangles symptoms related to apathy, depression, overlapping symptoms, and somatic complaints. Such scoring may be important in providing useful information regarding differential treatment options.
authors: Department of Clinical and Health Psychology, University of Florida, Gainesville, Florida 32611, USA. dawnbowers@phhp.ufl.edu
authors: Lindsey
authors: L
authors: Kirsch-Darrow
authors: Michael
authors: M
authors: Marsiske
authors: Michael S
authors: MS
authors: Okun
authors: Russell
authors: R
authors: Bauer
authors: Dawn
authors: D
authors: Bowers
mesh_terms: D000368:Aged; D057565:Apathy / Q000502:physiology*; D003863:Depression / Q000175:diagnosis / Q000453:epidemiology*; D005163:Factor Analysis, Statistical; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000453:epidemiology* / Q000523:psychology*; D011569:Psychiatric Status Rating Scales; D015203:Reproducibility of Results