Ages at Onset of Anxiety and Depressive Disorders in Parkinson's Disease.

OBJECTIVE

Parkinson's disease (PD) is a quintessential neuropsychiatric condition in which anxiety and depressive symptoms are common and may precede motor manifestations. The authors explored the ages at onset of anxiety and depressive disorders among patients with PD evaluated by psychiatrists at a deep brain stimulation center.

METHODS

Psychiatric diagnoses and ages at onset were collected via clinical interviews. The ages at PD diagnosis were ascertained by chart review. Onset ages for anxiety and depressive disorders (overall and for specific disorders) were compared with patients' ages at PD diagnosis by using t tests. Onset ages for major depressive disorder (MDD), generalized anxiety disorder (GAD), and panic disorder were compared with typical onset ages in the general population by using the sign test. A total of 108 patients (66.7% men; age 63.7 years [SD=8.9]) were included in the analysis.

RESULTS

Anxiety and depressive disorders occurred significantly earlier than PD diagnoses. Among patients whose anxiety and depression predated motor symptoms, the mean age at onset of anxiety disorders was 25.6 years earlier, and the mean age at onset of depressive disorders was 17.6 years earlier compared with the mean age at PD diagnosis (both p values <0.0001). Median onset ages for MDD (p<0.0001), GAD (p=0.0002), and panic disorder (p=0.0005) were significantly higher than typical median onset ages in the general population.

CONCLUSIONS

These results may indicate that neurodegenerative changes are present in parts of the brainstem reticular core and limbic system before motor circuits are affected to a degree that causes motor symptoms. Psychiatrists should be mindful that onset of MDD, GAD, and panic disorder after age 45 might signal a neurodegenerative movement disorder such as PD.