Kathryn R. McDonald, Esther Chilman, Michelle Barraclough, Rebecca Elliott and Iracema Leroi
Objective: Non-motor changes in Parkinson’s disease (PD) can include behavioural disturbances, such as apathy and impulse control disorders (ICDs). These behavioural problems impact on quality of life and carer burden. In the case of impulsivity, there is some association with specific personality styles at the time of assessment. This study compares current and pre-morbid personality attributes among people with PD who experience a clinically significant ICD, apathy, or no behavioural disturbance. Methods: 94 PD participants without dementia (ICD, n=34; apathy, n=24; control, n=36) were examined for current and pre-morbid (10 years before PD onset) personality style using self- and informant- versions of the NEO Five-Factor Inventory. All informants were knowledgeable about patients’ midlife personalities and provided both current and pre-morbid ratings. Results: When key co-variates (depression, anxiety, age and dopamine load) were controlled for, a difference in self-reported current personality style was found among the three PD groups, with the ICD group rating themselves as less agreeable compared to those with apathy or no behavioural disorder. Informant-rated current and pre-morbid measurements of personality style did not differ. Conclusion: While PD patients with clinically significant ICDs currently report themselves as being less agreeable, their informants did not support this finding and reported no change from pre-morbid personality. Differences in personality style with impulsive-compulsive behaviours in PD may not be discernable to others and may be related to transient ‘state’ factors (i.e. influenced by the disease process or response to treatment), rather than the more enduring trait characteristics exhibited prior to the onset of PD. Until longitudinal investigation of personality determinants has been conducted, there should be a cautious approach in screening for at-risk individuals using specific personality attributes, to avoid overlooking persons with PD who may be vulnerable to developing behavioural complications.