Background and purpose: Whilst disorders of emotion are commonly comorbid with Parkinson's disease (PD), evidence concerning their association with PD risk is limited. We investigate the prospective association between selected measures of emotional health and incident suspected PD.
Methods: 20,855 men and women, considered PD-free at baseline, completed a postal assessment of major depressive disorder (MDD), generalized anxiety disorder (GAD), psychological distress [defined by the five-item Mental Health Inventory (MHI-5)], and neuroticism. PD case ascertainment was based upon PD medication use, self-report questionnaires, hospital record discharge codes, and death certification, subsequently checked against general practitioner, hospital records and neurological service records.
Results: 175 suspected cases of incident PD were identified in 160,725 (median 7.9) person-years of follow-up (with 43 recorded in neurological service records). MDD lifetime history, GAD lifetime history, MHI-5 and neuroticism were all significantly associated with suspected PD following adjustment for age, sex, cigarette smoking, alcohol consumption, social class and education.
Conclusions: This study supports an association between measures of emotional health, assessed prior to evidence of motor symptoms, and subsequent suspected PD diagnosis. However, we were unable to determine whether our measures of personality and emotional health represent genuine premorbid risk factors or early stages of PD. Long-term prospective healthy cohort studies are required to investigate the relationship between emotional health history and the evolution of the premotor and motor phases of PD.