Taylor Rush, PhD, is a clinical psychologist at the Cleveland Clinic’s Center for Neurological Restoration. She differentiates Parkinson’s disease-related psychosis from similar symptoms caused by other conditions such as bipolar disorder or schizophrenia.

It’s important to recognize that most people don’t spontaneously develop hallucinations or delusions late in life from mental illnesses such as bipolar disorder or schizophrenia. Often, individuals who have a primary mental health condition may have already had a history of episodic hallucinations or delusions since their early- to mid-adulthood.

So it’s incredibly important for providers to talk about this with their patients to better understand the possible origins of someone’s psychosis.

Often, the person with Parkinson’s has some insight into the hallucinations not being real when they start, and you don’t necessarily see that in other mental illnesses.

We often also see that, with Parkinson’s disease hallucinations, they’re more likely to occur in dimmer lighting and towards the evening hours, because again, visual misperceptions seem to be a higher rate than other types of hallucinations.

So for those with chronic mental illnesses, hallucinations are often more persistent and distressing. And again, there may be less insight than those with Parkinson’s-related psychosis.