Man staring into distance

Psychosis can be a frightening word that many people simply don’t understand. But what does it really mean? In Parkinson’s disease (PD), what your doctor calls psychosis usually starts with mild symptoms, but these can have a big impact on quality of life. Healthcare providers usually refer to these symptoms as "Parkinson's disease associated psychosis." Psychosis can vary from severe confusion (disordered thinking) to seeing things that aren’t there (hallucinations) to believing things that are not true (delusions).

It is important to report any hallucinations or delusions to your medical team, even if they are not bothersome.

How common is Parkinson's disease psychosis (PDP)?

Between 20-40% of people with Parkinson’s report the experience of hallucinations or delusions.

When followed as the disease progresses over the years, this number increases. The increase does not mean that the hallucinations are persistent across the majority of people with PD. However, it is important to note that these statistics sometimes include “delirium,” in which the symptoms are temporary due to medication that needs to be adjusted or infection that needs to be treated, and “isolated minor symptoms” or “minor hallucinations,” including illusions, where instead of seeing things that are not there (hallucinations), people misinterpret things that are really there.

These are the most common types of psychosis in people with PD, with different studies placing the occurrence between 25-70% of people with Parkinson’s. Typically, if the person with PD only has these minor hallucinations, their doctor will not prescribe an antipsychotic medication, though more significant psychosis that requires medication may develop over time. In one study, 10% of those with minor hallucinations had their symptoms resolved within a few years, while 52% saw their symptoms remain the same and 38% saw their psychosis symptoms get worse.

We recommend that people with Parkinson’s not use a single percentage to represent the prevalence of hallucinations and PDP. Parkinson’s is a complex disease and as it progresses the percentages and risk of symptoms will change.

What are hallucinations?

Hallucinations are when someone sees, hears or feels something that is not actually there. They are best described as deceptions or tricks played by the brain that involve the body’s senses. Hallucinations are not dreams or nightmares. They happen when the person is awake and can occur at any time of day or night.

What are illusions?

Illusions are another sensory misperception. Instead of seeing something that isn’t there, people with illusions misinterpret real things in the environment. For example, the clothes in the closet may look like a group of people.

Like visual hallucinations, illusions tend to occur in low light or low-visibility situations.

What are delusions?

Delusions are illogical, irrational, dysfunctional views or persistent thoughts that are not based in reality. They are not deliberate and are very real to the person with PD. People with delusions who feel threatened may become argumentative, aggressive, agitated or unsafe.

  • Delusions are less common in PD than visual hallucinations. They affect about 8% of people with PD.
  • Compared to hallucinations, delusions tend to be more complicated, present a greater risk for behavioral disturbances and safety concerns, are typically more difficult to treat and represent a more obvious deterioration or decline in one’s condition.
  • Delusions can begin as generalized confusion at night. Over time, confusion can develop into clear delusions and behavioral disturbances during the day.
  • Paranoia can lead to medication noncompliance — a person refusing to take medications, believing they are poisonous or deadly.
  • Delusions can be associated with dementia. As a result, people with delusions are often confused and extremely difficult to manage. In these cases, many caregivers require outside assistance.

All forms of delusions can be seen with PD, although delusions of jealousy and persecution (like paranoia) are most widely reported and represent a greater challenge for treatment. These delusions can lead to aggression, which can pose a serious safety risk to the person with PD, family members and care partners.

Some examples of delusions and their impact in PD include:

  • Jealousy
    • Belief: Your partner is being unfaithful.
    • Behavior: Paranoia, agitation, suspiciousness, aggression
  • Persecutory
    • Belief: You are being attacked, harassed, cheated or conspired against.
    • Behavior: Paranoia, suspiciousness, agitation, aggression, defiance, social withdrawal
  • Somatic
    • Belief: Your body functions in an abnormal manner. You develop an unusual obsession with your body or health.
    • Behavior: Anxiety, agitation, reports of abnormal or unusual symptoms, extreme concern regarding symptoms, frequent visits with the clinician

What causes hallucinations and delusions?

Medication, dementia and delirium are the three main contributors to the development of psychosis in Parkinson’s disease. Determining the cause can be difficult because these conditions can overlap and produce similar symptoms. Once a probable cause is determined, treatment can begin.

diane_s
MY PD STORY: Diane S.

"He would tell me about seeing groups of people in the living room, particularly at night. A man he dubbed “Big Boy” slept in our bed and, sometimes, Jay felt he needed to physically confront him, which could be scary."

Risk Factors for Psychosis

Not everyone with Parkinson’s will develop hallucinations or delusions, but there are several things can increase your risk:

  • Dementia or impaired memory
  • Depression: Individuals suffering from depression and PD are at a greater risk. In addition, severe depression alone can cause psychosis.
  • Sleep disorders, such as vivid dreaming. Individuals commonly report vivid dreaming prior to the onset of psychosis. Other associated sleep disturbances include REM sleep disorder and general insomnia.
  • Impaired vision
  • Older age
  • Advanced or late-stage PD
  • Use of PD medications

Treating Psychosis

Treating Parkinson’s disease psychosis is a multistep process that begins with talking to your healthcare team. They will follow a series of steps to figure out how best to address your symptoms.

  • Step 1. The first step is to perform a clinical evaluation of your symptoms considering prior history, disease stage and available support systems. This assessment will help determine if something is medically wrong and you need treatment right away, or if you can keep an eye on the condition and wait.
  • Step 2. Treatment, when needed, generally begins with adjustment of your PD medications and referral to counseling. If there is nothing medically wrong with you, your doctor may reduce or eliminate medications, often in a specific order, to lessen the symptoms of psychosis. This is a balancing act as dopamine, which is used to steady your motor symptoms, can also, in high levels, increase psychological side effects.
  • Step 3. If further intervention is needed, your doctor may initiate antipsychotic therapy, using drugs to rebalance the chemical levels in the brain and reduce episodes of hallucinations, illusions, and delusions

Medications Used for Treating Psychosis

Antipsychotic agents are designed to balance abnormal chemical levels in the brain. Up until the 1990s, the use of antipsychotics in PD was controversial because the drugs used until that time work by reducing excess dopamine. This alleviated psychosis but caused dramatic worsening of PD motor symptoms.

Fortunately, medications that are better tolerated by people with PD are now available. Today, there are three antipsychotic medications considered relatively safe for people with PD. They cause limited worsening of PD while treating hallucinations and delusions.

Many antipsychotic medications can worsen motor symptoms and should not be prescribed for people with PD. Some of these medications, such as haloperidol (Haldol), are commonly prescribed in the hospital setting for patients who are agitated or anxious.

Treating clinicians should be aware that certain antipsychotic medications can make the condition of the person with PD worse.

How to Talk to Someone with Hallucinations or Delusions

  • It is usually not helpful to argue. Avoid trying to reason. Keep calm and be reassuring.
  • You can say you do not see what your loved one is seeing, but some people find it more calming to acknowledge what the person is seeing to reduce stress. For example, if the person sees a cat in the room, it may be best to say, "I will take the cat out" rather than argue that there is no cat.

Page reviewed by Dr. Kathryn P Moore, Movement Disorders neurologist at Duke Health, a Parkinson's Foundation Center of Excellence.

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