Treatment of cognitive, psychiatric, and affective disorders associated with Parkinson's disease.

Neuropsychiatric symptoms are common in Parkinson's disease (PD) and add significantly to the burden of disease. These symptoms are most commonly part of the disease spectrum owing to pathological changes within relevant brain regions. Neuropsychiatric problems include disorders of cognition, ranging from mild cognitive impairment to dementia, psychotic symptoms, including, most commonly, well-formed visual hallucinations and paranoid delusions, and mood disorders, such as depression and anxiety. The other common cause of neuropsychiatric problem is secondary to use of dopaminergic drugs. Some PD patients may develop behavioral disorders, including impulse control disorders (ICDs) and addictive symptoms. Psychosis can be due to a mixture of underlying pathology, with triggering or worsening of symptoms with changes to PD medications. Currently, management of these disorders primarily uses therapies developed for general psychiatry and cognitive neurology, rather than specifically for PD. However, significant adverse effects, such as worsening of the motor symptoms of PD, can limit use of some drug therapies. Identification of drug-induced symptoms, such as ICDs, enables withdrawal of the offending drug as the principal management strategy. Research is ongoing in an effort to develop more specific therapies for PD-related neuropsychiatric symptoms.