[Psychiatric Symptoms in Parkinson's Disease: Epidemiology, Pathophysiology, and Therapeutic Strategies]

Although traditionally classified as a movement disorder due to nigrostriatal dopamine loss, Parkinson's disease also manifests a wide range of psychiatric symptoms across the disease course from prodromal phase to advanced stages. These psychiatric symptoms include depression, anxiety, apathy, impulse control disorders, hallucinations, and delusions. The emergence of psychiatric symptoms reflects the dysfunction of the dopaminergic system and multiple neurotransmitter systems (e.g., serotonergic, noradrenergic, and cholinergic systems) and disruption of large-scale brain networks. Providing optimal care requires stage- and symptom-specific strategies, such as optimizing dopaminergic therapy, judiciously using atypical antipsychotics, and considering acetylcholinesterase inhibitors when appropriate. This review summarizes the epidemiology, pathophysiology, and treatment of the psychiatric symptoms in Parkinson's disease, highlighting individualized management strategies that align with the underlying mechanisms.