Retrospective real-world analysis found bilateral STN-DBS produced short-term improvements in most neuropsychiatric symptoms but a marked increase in cognitive decline between 1–5 years post-DBS, with recent pre-DBS mood symptoms and hallucinations predicting later complications.

Offers clinically actionable data for patient selection, risk stratification, and post-DBS monitoring that can guide trial design and adjunctive therapeutic strategies to mitigate late cognitive decline, but provides limited mechanistic insight for direct drug-discovery targets.

BACKGROUND: Effects of subthalamic nucleus Deep Brain Stimulation (DBS) for Parkinson's Disease on neuropsychiatric symptoms remains unclear, especially in the local context. OBJECTIVES: To describe the frequencies, characteristics, and predictive factors of neuropsychiatric symptoms occurring before and up till 5 years after DBS for Parkinson's disease. METHOD: Demographic and clinical data from a database of patients who underwent DBS for Parkinson's disease from April 2014 to April 2022 were retrospectively analysed. Neuropsychiatric symptoms were identified from medical records at four time-points: any time pre-DBS, only within 1 year pre-DBS, up to 1-year post-DBS (early-onset), and between 1 and 5 years post-DBS (later-onset). Outcomes included depressed mood, anxiety, cognitive decline, hallucinations, impulse control disorders and poor sleep. RESULTS: DBS had an early beneficial effect on neuropsychiatric symptoms except for impulse control disorders (12.5% vs 10.4%, p = 1.0 and 10.4% vs 20.8%, p = 0.388) and cognitive decline (10.4% vs 12.5%, p = 1.0 and 10.4% vs 20.8%, p = 0.297). After 1 year, occurrences of neuropsychiatric outcomes approximated pre-DBS frequencies except for excess cognitive decline (52.1% vs 12.5%, p < 0.001 and 52.1% vs 20.8%, p = 0.007). Presence of recent pre-DBS mood symptoms predicted late-onset mood symptoms (adjusted odds ratio = 5.5, 95% CI 1.4-21.3, p = 0.014) and presence of recent pre-DBS hallucinations predicted early-onset post-DBS hallucinations (adjusted odds ratio = 36.4, 95% CI 1.4-962.8, p = 0.031). CONCLUSION: There are likely at least short-term benefits on neuropsychiatric symptoms after bilateral subthalamic nucleus DBS for Parkinson's Disease.