Modeling anxiety in Parkinson's disease.

ABSTRACT

BACKGROUND: The aim of this work was to construct a model for anxiety in PD and compare the relative contributions of PD-specific and -nonspecific general population risk factors for anxiety in this model. METHODS: Structural equation modeling of associations of risk factors with the anxiety outcome using a cross-sectional data set of 342 patients with PD were used. RESULTS: A model with acceptable to good fit was generated that explained 65% of the variance in anxiety scores. A previous history of depression and the severity of the depressive symptoms scored on the Hamilton Depression Rating Scale were the only nonspecific variables with a direct effect on anxiety. The presence of motor fluctuations and disease-related decline in activities of daily living were PD-specific markers of anxiety. Nonspecific risk factors had a greater influence in the model than PD-specific risk factors. Standardized regression coefficients suggested that the Hamilton Depression Rating Scale score was the most important contributor to the variation in anxiety. A post-hoc analysis showed that the effects of the following variables on anxiety levels were fully mediated by depression sex; family history of depression; previous history of anxiety; cognitive status; difficulties in non-disease-specific activities of daily living; and severity of motor signs. CONCLUSION: In this cross-sectional study, we showed that nonspecific general population risk factors are more important markers for anxiety than PD-specific risk factors. Depression was the most prominent marker. PD-specific markers for anxiety appear to be more situational and related to off periods and disease-specific disturbances of activities of daily living.