Exploring the link between personality dimensions and non-motor fluctuations in Parkinson's disease

BackgroundParkinson's disease (PD) patients on dopaminergic drugs may experience non-motor fluctuations (NMFs) which are often heterogeneous and respond variably to treatments.ObjectiveWe evaluated if personality was associated to NMFs and could modulate the NMFs responsiveness to dopaminergic medication and deep brain stimulation of the sub-thalamic nucleus (STN-DBS).MethodsFrom the PREDISTIM cohort, personality dimensions of 235 PD patients were assessed by the Temperament and Character Inventory (TCI) before STN-DBS (V0). NMFs were evaluated using the NMFs Severity Scale at V0 and one year after STN-DBS (V1). Linear regression models were performed between TCI dimensions and NMFs at V0; and logistic regression models were done between TCI dimensions and 1) groups of dopa-sensitive patients (responders to ON medication at V0) versus non-dopa-sensitive ones, and 2) responders versus non-responders to STN-DBS at V1. Odds ratios (OR) were also calculated.ResultsSignificant associations were found between two TCI personality dimensions ("Harm Avoidance" and "Self-Directedness") and severity of NMFs in OFF medication at V0: PD patients with higher Harm Avoidance and lower Self-Directedness scores having more NMFs. TCI personality dimensions were not associated with the dopa-sensitivity while Novelty Seeking was significantly associated with the STN-DBS-responder group for the psychiatric (OR = 1.09 [1.02-1.17]) and for the dysautonomic NMFs (OR = 1.11 [1.04-1.18]).ConclusionsCertain personality dimensions (Harm Avoidance and Self-Directedness) are associated with NMFs severity at baseline, and PD patients with high Novelty Seeking seem to be better candidates for NMFs improvement after STN-DBS.