Anxious personality predicts an increased risk of Parkinson's disease

We studied the association of three personality traits related to neuroticism with the subsequent risk of Parkinson's disease (PD) using a historical cohort study. We included 7,216 subjects who resided within the 120-mile radius centered in Rochester, MN, at the time they completed the Minnesota Multiphasic Personality Inventory (MMPI) for research at the Mayo Clinic from 1962 to 1965. We considered three MMPI personality scales (pessimistic, anxious, and depressive traits). A total of 6,822 subjects (94.5%) were followed over four decades either actively or passively. During follow-up, 227 subjects developed parkinsonism (156 developed PD). An anxious personality was associated with an increased risk of PD [hazard ratio (HR), 1.63; 95% confidence interval (CI), 1.16-2.27]. A pessimistic personality trait was also associated with an increased risk of PD but only in men (HR = 1.92; 95% CI = 1.20-3.07). By contrast, a depressive trait was not associated with increased risk. Analyses combining scores from the three personality scales into a composite neuroticism score showed an association of neuroticism with PD (HR = 1.54; 95% CI = 1.10-2.16). The association with neuroticism remained significant even when the MMPI was administered early in life (ages 20-39 years). By contrast, none of the three personality traits was associated with the risk of non-PD types of parkinsonism grouped together. Our long-term historical cohort study suggests that an anxious personality trait may predict an increased risk of PD developing many years later.