Objective: The objective of this study is to identify pre-operative cognitive characteristics of patients who are candidates for deep brain stimulation surgery that may contribute to development of dementia years after surgery.

Background: Presence of significant cognitive impairment is a risk factor for post-operative cognitive worsening in patients with Parkinson’s Disease (PD) undergoing deep brain stimulation (DBS) surgery.  Among the non-motor symptoms of PD, cognitive impairment is one of the most disabling symptoms. The goal of our study is to determine whether a pre-operative cognitive phenotype in patients who are deemed to be good candidates for surgery contributes to the development of dementia in the years after surgery. Understanding whether particular cognitive weaknesses lead to higher rates of dementia assists with identification of high-risk individuals for counseling, planning, and enrollment in clinical trials.

Method: In this retrospective multivariable modeling study, we reviewed the electronic medical record and DBS surgical and neuropsychological data for PD patients who underwent DBS in the Center for Neurological Restoration between 2012-2021. The model outcome variable was the presence or absence of new dementia diagnosis in the patient’s electronic health record following DBS surgery. Pre-operative neuropsychological data was entered into a Random Forest Model to create up to three cognitive phenotypes. Phenotype, demographic, clinical, and surgical variables were entered as independent variables in the Cox Proportional Hazards Models.

Results: Based on preliminary data, we hypothesize that the phenotype with the most prominent verbal memory impairment will be associated with a higher likelihood of dementia diagnosis post-surgically. Based on prior work, we also hypothesize that age and presence of akinesia or rigidity, but not surgical variables, will contribute to the likelihood of dementia diagnosis post-surgically.

Conclusion: Among the general PD population, advancing age and motor phenotype are strongly associated with risk of developing cognitive impairment. A clearer understanding of risk factors in patients cleared for DBS would be helpful for post-surgical monitoring and care.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/modeling-dementia-in-patients-with-parkinsons-disease-years-after-dbs/