Psychosis and Parkinson’s Disease

Abstract

Parkinson's disease (PD) psychosis is a common phenomenon that affects quality of life, caregiver burden, and disability in patients with PD. Although there may be an increased risk of psychosis inherent to the disease itself, current research suggests that dementia, advancing age, and concomitant medication use increase the risk of psychosis in PD. Symptoms of psychosis in this population may include hallucinations, delusions, paranoia, false sense of presence, and illusions. Early intervention may be important for delaying progression of psychotic symptoms. Treatment options for PDrelated psychosis include reduction of dopaminergic therapy, switch to levodopa, simplification of polypharmacy and addition of an atypical antipsychotic, such as quetiapine and clozapine.Parkinson's disease (PD) is a chronic, progressive neurodegenerative disorder characterized by tremor, bradykinesia, rigidity, and postural instability. The presence of psychotic symptoms, or PD psychosis (PDP), is a recognized symptom cluster, and has serious consequences for patients. Psychotic symptoms experienced by PD patients may include hallucinations (primarily visual, but also auditory), illusions, paranoia, delusions, and a milder 'false sense of presence' . Psychotic symptoms are associated with poorer quality of life, disability, caregiver distress and worse outcomes including mortality and nursing home placement [1,2]. Given the impact of psychosis on this chronic, progressive neurodegenerative disease, current research aims to further understand the epidemiology of psychotic symptoms, the risk factors for psychosis, and most appropriate treatments.The prevalence of psychotic symptoms varies widely in the literature and may be as high as 60% in the PD population [3][4][5][6]. A recent population-based study of PDP revealed an incidence of 797 per 1,000 person-years. At the end of the 12-year study period, 60% of patients had developed psychotic symptoms [7]. The difficulty in assessing the frequency of this condition may be related to a lack of consensus on methods to define what constitutes PDP, subsequent use of multiple rating scales in the literature, and differences in study design and patient population. An expert