This prospective observational cohort study aims to investigate whether intracranial Local Field Potentials (LFPs) recorded from implanted Deep Brain Stimulation (DBS) devices are associated with neuropsychiatric symptoms in people with Parkinson's disease (PD). The study will focus on paroxysmal anxiety, impulse control disorders, and hallucinations.

Twenty participants with Parkinson's disease and an implanted Medtronic Percept DBS device will be recruited. Participants will complete behavioural and clinical assessments and will use the event-marking functionality of the DBS device to record symptom episodes over a monitoring period of approximately 120 days. Brain activity will be passively recorded during this period.

The study will evaluate relationships between LFP signals, symptom occurrence, behavioural task performance, and clinical symptom severity measures. Machine learning approaches will be used to identify electrophysiological patterns associated with neuropsychiatric symptom states at an individual level.

The findings may improve understanding of the neural mechanisms underlying neuropsychiatric symptoms in Parkinson's disease and support the future development of personalised adaptive neuromodulation approaches.

Inclusion Criteria:

• Age ≥ 18 years
• A diagnosis of Parkinson's Disease
• A diagnosis of hallucinations, impulse control disorder, or panic disorder (episodic anxiety)
• Previous bilateral DBS implantation with a Medtronic Percept device as part of clinical care

Exclusion Criteria:

• Non-English speakers
• <18 years old or >75 years old
• A history of concurrent conditions that could significantly confound the study results, such as other significant neurological condition (e.g., brain injury/infection, substance abuse) or concurrent severe psychiatric condition (e.g., schizophrenia)
• Moderate/severe Intellectual Disability or inability to understand study procedures
• Lack of capacity to consent to the study
• Currently involvement in other studies

Adults with Parkinson's disease and co-occurring neuropsychiatric symptoms, including hallucinations, impulse control disorder, or episodic anxiety, who previously underwent bilateral Deep Brain Stimulation implantation with a Medtronic Percept device as part of routine clinical care at King's College Hospital or affiliated services.

Individual participant data that underlie the results reported in publications may be shared in anonymised form with qualified researchers upon reasonable request and subject to applicable ethical and institutional approvals. Data sharing will comply with participant consent, data protection regulations, and institutional policies.