With 10 million of patients across the world, Parkinson's disease is the second most common form of neurodegeneration, after Alzheimer's. Among half of patients develop psychotic symptoms, such as visual hallucinations and delusions, which are correlated with higher rate of placement in nursing home, are difficult to treat and severely affect quality of life, making Parkinson's disease psychosis (PDP) a major public health issue.

The aim of this study is to identify treatment options that could be used to treat PDP and clarify underlying pathophysiology.

We conducted a literature review on Pubmed, Goggle scholar and Cochrane library, using a combination of the following: “Parkinson's disease Psychosis” “visual hallucinations” “Pimavanserin” “Clozapine” “atypical anti-psychotics” 120 articles were screened.

Considering that hallucinations arise from overactivation of dopaminergic receptors, treatment options include reducing the dopaminergic drugs used to control motor symptoms; using atypical anti-psychotics such as Risperidone, Olanzapine, Quetiapine, which often results in the worsening of extra-pyramidal symptoms. Another option is the use of low doses of Clozapine, which has been proven efficient with no worsening of non-motor symptoms, suggesting the implication of other pathways, such as serotonin. Finally, Pimavanserin, a 5-HT2A receptor inverse agonist, without any dopaminergic activity, has been demonstrated to be effective in the treatment of PDP, well tolerated and easy to use.

Serotonin inverse agonists represent a major breakthrough in the pharmacotherapy of PDP, and may lead the way to changes in the treatment of schizophrenia and other psychotic disorders.

The authors have not supplied their declaration of competing interest.