The Protective Role of Cognitive Reserve: A Preliminary Study on Parkinsonian Patients Undergoing Deep Brain Stimulation.

Background/Objectives: High cognitive reserve (CR) has been shown to have beneficial effects on global cognition, cognitive decline, and risk of dementia in Parkinson's disease (PD). We evaluated the influence of CR on the long-term cognitive outcomes of patients with PD who underwent subthalamic nucleus deep brain stimulation (STN-DBS). Methods: Twenty-five patients with PD underwent neuropsychological screening using the Montreal Cognitive Assessment (MoCA) at baseline, 1 year, and 5 years after bilateral STN-DBS. CR was assessed using the Cognitive Reserve Index questionnaire. According to CR score, patients were assigned to two different groups (LowCR group ≤ 130, HighCR group > 130). Results: Our data showed that patients in the HighCR group obtained a better performance with the MoCA total score at long-term follow-up compared to those in the LowCR group ([mean ± SE] LowCR group: 21.4 ± 1.2 vs. HighCR group: 24.5 ± 1.3, p = 0.05). The cognitive profile of the HighCR group remained unchanged over time. Conversely, the LowCR group had worse global cognition 5 years after surgery (T0: 25.3 ± 0.6 vs. T2: 21.4 ± 1.2, p = 0.02). Cognitive decline was not associated with mood, demographics, or clinical variables. Conclusions: These preliminary findings suggest that higher CR may be protective in PD cognition after STN-DBS. Specifically, a high CR may help cope with long-term decline in the context of surgical treatment. Quantifying a patient's CR could lead to more personalized medical care, tailoring postoperative support and monitoring for those at higher risk of cognitive decline.