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Psychotic Symptoms

Reviewed by: HU Medical Review Board

Psychosis can be a scary word for many people. They might not understand what it means. The best way to think of psychosis is as a state in which a person cannot tell what is real and what is not. Psychotic symptoms occur in up to 4 out of 10 people with Parkinson’s disease (PD).1

People who have Parkinson’s disease psychosis may:1

  • Have profound mental confusion (disordered thinking)
  • See things that are not there (hallucinations)
  • Believe things that are not true (delusions)

Disordered thinking

Disordered thinking is a common symptom of psychosis. It refers to the difficulty a person has in sorting out and making sense of information. This difficulty can lead to confusion. A person with disordered thinking may have trouble understanding what is happening around them.1


Hallucinations are one of the most common symptoms of psychosis. They are perceptual disturbances that occur in the absence of an external stimulus. In other words, people who have hallucinations experience things that are not really there. Hallucinations can be:1

  • Auditory (hearing things)
  • Visual (seeing things)
  • Olfactory (smelling things)
  • Gustatory (tasting things)
  • Tactile (feeling things)

Hallucinations can be frightening. They can cause a person to feel as though they are losing their grip on reality.1


Delusions are false beliefs that a person holds despite evidence to the contrary. They are another of the most common symptoms of psychosis.1

Delusions can be about anything. Common delusions include the beliefs that:1

  • Someone is out to get you
  • You are being followed
  • You have special powers or knowledge

Delusions can be very distressing. People who experience them can become argumentative, aggressive, or unsafe.1


Agitation is also a common symptom of psychosis. It refers to the feeling of being restless, irritable, and tense. An agitated person may feel as though they need to move all the time or cannot sit still. They may yell or act demanding.2

While agitation is common with psychosis, it can also occur with other mental health problems like depression or anxiety.2

Why does PD cause psychosis in some people?

There are several reasons why PD can cause psychosis in some people. The disease itself can cause changes in the brain that lead to psychotic symptoms. These symptoms often occur in those with PD-associated cognitive impairment or dementia. PD drugs can also cause psychosis, as can other medical conditions like infections or strokes.3

Risk factors

Some people with PD are more at risk for having psychotic symptoms than others. Risk factors that increase the likelihood of psychosis include:1,3

  • Older age
  • Severe or advanced disease
  • Use of PD medicines like levodopa
  • Vision problems
  • Sleep problems
  • Dementia or memory problems
  • Depression or other mood disorders


Psychosis in PD can be hard to diagnose. To make a diagnosis, a doctor will need to do a detailed exam and rule out other possible causes of the symptoms. This may involve doing tests like blood work or advanced imaging scans.1


There is no one-size-fits-all treatment for psychosis in PD. The approach will vary depending on the person and the type of psychosis they are experiencing. Common treatments include:1

It is important to seek treatment for psychosis as soon as possible, as it can be very distressing for both the person experiencing it and their loved ones. If you or a loved one is experiencing psychosis, it is important to seek help.1

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