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.

Differential impact of behavioral, social, and emotional apathy on Parkinson's disease

“…Our finding dovetails with other reports which show that apathy can be dissociated from depression in PD. Apathy frequently occurs in the absence of depression10, and factor analyses have revealed that the two represent discrete constructs 10. The findings presented here go further by highlighting the importance of considering the multidimensional nature of apathy when assessing relationships with depression.…”

“…However, in healthy controls, those who were more emotionally apathetic actually tended to be less depressed. Our finding that depression is negatively associated with ES in healthy controls but not in PD adds to existing studies regarding complex associations between apathy and depression 10. Importantly, this result suggests that different clinical approaches toward apathy in patients with PD compared to the general population might be needed 24.…”

“…Previous studies have yielded mixed results; both greater emotional apathy but preserved executive motivation8 and preserved emotional motivation but executive and initiation deficits9 have been reported. Moreover, apathy appears to have overlapping symptoms with other comorbid states associated with altered motivation, particularly depression10 and anhedonia 11. It remains to be established whether different apathy domains in PD relate specifically to these syndromes.…”

Impaired ability to imagine future pleasant events is associated with apathy in schizophrenia

“…The total score ranges from 0 to 63, with higher scores reflecting greater depression. Recently, Kirsch-Darrow et al (2011) proposed a "factor-based" scoring of the BDI-II that disentangles symptoms related to apathy (loss of interest/pleasure factor), depression (dysphoric mood factor) and somatic complaints (somatic factor). In our study, we used this factor structure in order to have a "pure" measure of depression that did not overlap with apathy components.…”

“…Thus, the Benjamini-Hochberg-Yekutieli correction exerts a less stringent control over false discovery than familywise error rate procedures (such as the Bonferroni correction) and improves power to some extent (Narum, 2006). Finally, to control the influence of other factors not specifically related to depression and nonetheless measured by classical clinical inventories such as the BDI-II, we used the factor analysis of the BDI-II proposed by Kirsch-Darrow et al (2011).…”