Dopamine-related personality traits in Parkinson's disease

Studies suggest that Parkinson's disease (PD) is associated with a particular group of personality characteristics. With relative uniformity, PD patients are described as industrious, rigidly moral, stoic, serious, and nonimpulsive. In this controlled study, we used a recently developed personality questionnaire, Cloningers's Tridimensional Personality Questionnaire, to test the hypothesis that these personality traits are behavioural manifestations of damaged dopaminergic pleasure and reward systems. We found significantly less (p < 0.01) of a group of traits called "novelty seeking" in PD patients compared with matched medical controls. Patients with low novelty seeking are described as being reflective, rigid, stoic, slow-tempered, frugal, orderly, and persistent, characteristics similar to those in the clinical description of PD patients. We review evidence supporting the claim that novelty seeking is dopamine-dependent, and suggest that damage to the mesolimbic dopaminergic system causes the described personality profile of PD patients.