Personality Changes After Subthalamic Nucleus Stimulation in Parkinson's Disease.

BACKGROUND: While deep brain stimulation of the subthalamic nucleus (STN-DBS) significantly improves motor deficits in patients with Parkinson's disease (PD), it is still unclear whether it affects personality functioning. OBJECTIVE: The objective of the present study was to examine personality changes in patients with PD after STN-DBS from the perspectives of both the patients and caregivers. Moreover, by assessing the premorbid personalities of the patients, we tried to determine individual vulnerability to STN-DBS-induced personality changes. METHODS: In total, 27 patients and their caregivers participated in our retrospective observational study. They were asked to assess the patients' personality changes with the Iowa Scale of Personality Changes (ISPC) and the patients' premorbid personalities with the Big Five Inventory (BFI). RESULTS: Caregivers reported significant personality changes in the ISPC domains of Executive Disturbance (p = 0.01) and Disturbed Social Behavior (p = 0.02). Most of the ISPC domains were positively correlated with Conscientiousness, while Executive Disturbance was negatively correlated with Neuroticism of the BFI scale. CONCLUSION: Our results show that executive and social functioning are the two most vulnerable domains in patients with PD after STN-DBS, especially in those patients who score higher for neuroticism and lower for conscientiousness on the BFI scale. The results of our study may provide movement disorder specialists with better counseling options and better selection of DBS candidates. Caregivers' perspective might contribute significantly in understanding postoperative personality changes.

Cholinergic basal forebrain and hippocampal structure influence visuospatial memory in Parkinson's disease.

Visuospatial impairment in Parkinson's disease (PD) heralds the onset of a progressive dementia syndrome and might be associated with cholinergic dysfunction. It remains unclear however, whether degeneration of the cholinergic basal forebrain is directly related to cognitive decline, or whether relationships between this region and cognitive function are mediated by closely related brain structures such as those in the medial temporal lobe. To evaluate relationships between structure of the cholinergic basal forebrain, medial temporal lobe and cognition, 27 PD patients without dementia and 20 controls underwent neuropsychological assessment and MRI. Volumes of the cholinergic basal forebrain nuclei, the entorhinal cortex, the hippocampus and its subfields were measured. Regression models utilised basal forebrain and hippocampal volumetric measures to predict cognitive performance. In PD, visuospatial memory (but not verbal memory or executive function) was correlated with hippocampal volume, particularly CA2-3, and basal forebrain subregion Ch1-2, but not Ch4. In addition, hippocampal volume was correlated with Ch1-2 in PD. The relationship between Ch1-2 and visuospatial memory was mediated by CA2-3 integrity. There were no correlations between cognitive and volumetric measures in controls. Our data imply that the integrity of the cholinergic basal forebrain is associated with subregional hippocampal volume. Additionally, a relationship between visuospatial function and cholinergic nuclei does exist, but is fully mediated by variations in hippocampal structure. These findings are consistent with the recent hypothesis that forebrain cholinergic system degeneration results in cognitive deficits via cholinergic denervation, and subsequent structural degeneration, of its target regions.