Hallucinations and delusions are potential complications of Parkinson’s disease (PD). They may be severe enough to be classified as PD psychosis and can be related to a few factors, such as changes in the brain or medications.

Hallucinations are visual, auditory, or other perceptions that aren’t really there. Delusions are beliefs that aren’t based in reality, such as paranoia that persists even when a person is presented with contrary evidence.

Hallucinations during PD can be frightening and debilitating, but there are treatments that may help.

Hallucinations and delusions are often side effects of certain medications, but they could be related to other conditions, such as dementia, delirium, or PD-associated psychosis.

Psychosis symptoms may affect anywhere from 16% to 75% of people with PD. They often manifest in the later stages of the disease.

Though the exact biological mechanisms behind PD psychosis are still being studied, structural brain changes and an imbalance of neurotransmitters like dopamine and serotonin may both play a role. Medications that help manage PD can also trigger psychosis symptoms as side effects for some people.

Types of hallucinations and delusions

Most hallucinations with PD are fleeting and not usually harmful. They can become frightening or bothersome, though, especially if they occur frequently.

Hallucinations can be:

  • seen (visual)
  • heard (auditory)
  • smelled (olfactory)
  • felt (tactile)
  • tasted (gustatory)

Delusions are less common and can be more complex than hallucinations. They may also be more difficult to treat.

Delusions often start as confusion that develops into clear ideas that aren’t based on reality. Examples of the types of delusions people with PD may experience include:

  • Jealousy or possessiveness: The person believes someone in their life is being unfaithful or disloyal.
  • Persecutory: They believe that someone is out to get them or harm them in some way.
  • Somatic: They believe they have an injury or other medical problem.
  • Guilt: The person with PD has feelings of guilt not based in real behaviors or actions.
  • Mixed delusions: They experience multiple types of delusions.

Delusions may pose safety risks to caregivers and to the person with PD.

There are several reasons someone with PD might experience delusions or hallucinations.

Medications

People with PD often have to take several medications to help manage the symptoms of PD. However, these medications can have many side effects.

Taking medications that affect dopamine receptors is a significant risk factor for hallucinations and emotional symptoms in people with PD, because some PD medications work by increasing dopamine activity.

Medications that may contribute to hallucinations or delusions in people with PD include:

Make sure your doctor knows about all the medications you take so they can help you understand what to avoid or adjust.

Dementia

Chemical and physical changes in the brain can contribute to hallucinations and delusions. This is often seen in cases of dementia with Lewy bodies, which are atypical deposits of a protein called alpha-synuclein.

This protein builds up in areas of the brain that control:

  • behavior
  • cognition
  • movement

People with PD can develop dementia, especially as PD progresses. Additionally, conditions like multi-system atrophy, dementia with Lewy bodies, and progressive supranuclear palsy may cause PD symptoms along with dementia symptoms.

People with PD can also develop dementia independent of PD.

Delirium

Delirium is a temporary change in a person’s concentration or awareness. If someone has dementia, certain factors may trigger an episode of delirium, including:

  • a change in environment or an unfamiliar location
  • infections
  • electrolyte imbalances
  • fever
  • vitamin deficiencies
  • a fall or head injury
  • pain
  • dehydration

If a person with PD is experiencing a hallucination or delusion, there are some steps you can take to help them.

First, it’s important to note that arguing with someone experiencing hallucinations or delusions is rarely helpful. It’s important to remain calm and acknowledge the person’s thoughts.

Here are a few things to keep in mind:

  • If a person is telling you they see or hear something that you know isn’t there, that’s likely a hallucination. People with OD who experience hallucinations as a side effect of their medications might not be sure if what they’re seeing or hearing is real, and it’s typically easy to reason with them. Make an appointment with their doctor if they’re experiencing hallucinations.
  • If someone with PD is becoming forgetful and having difficulty focusing or following conversations, they may be developing dementia. Make an appointment with their doctor for an evaluation.
  • Agitation and confusion can be symptoms of delirium and require prompt medical attention.
  • Psychosis means a person has lost contact with reality and may be experiencing delusions. This requires immediate medical attention.

If a person is panicked or scared, the goal is to reduce their stress and keep them calm. It may help to try and distract them by bringing up another subject or taking them into a quiet room where they can unwind.

If it’s difficult to distract them or calm them down, talk with their doctor, who can help you find ways to manage these situations.

Psychosis means a person has lost touch with reality, either temporarily or for the long term. Symptoms of psychosis indicate a serious underlying condition that requires treatment, as it may lead a person to harm themselves or others.

People with dementia, delirium, or symptoms of psychosis may not be able to describe or understand their symptoms.

It may help to write down what you’re noticing about their symptoms, such as what they were doing before the hallucinations or delusions started, or what kinds of perceptions they may talk about. Then you can share this information with their doctor.

Your doctor may first reduce or change the PD medication you’re taking to see whether that reduces side effects. This is about finding a balance.

People with PD may need higher doses of dopamine medication to help manage motor symptoms. But dopamine activity shouldn’t be increased so much that it results in hallucinations and delusions. Your doctor will work with you to find that balance.

Medications to help manage side effects

Your doctor might consider prescribing an antipsychotic drug if reducing your PD medication doesn’t help manage the side effects.

Antipsychotic drugs should be used with extreme caution in people with PD. Some may worsen hallucinations and delusions and lead to other side effects.

Common antipsychotic drugs like olanzapine (Zyprexa) might improve hallucinations, but they often result in worsening PD motor symptoms.

Only one medication, pimavanserin (Nuplazid), is FDA approved specifically to help manage hallucinations and delusions in people with PD psychosis. It may help decrease the frequency and severity of hallucinations and delusions without worsening the primary motor symptoms of PD.

Pimavanserin shouldn’t be used in people with dementia-related psychosis due to an increased risk of death.

Psychosis symptoms caused by delirium may improve once the underlying trigger is managed.

Hallucinations and delusions may occur in people with PD due to factors like medication side effects or brain changes caused by the condition itself.

Doctors may be able to manage hallucinations or delusions by adjusting a person’s PD medications or prescribing other medications, like pimavanserin. If someone you know has PD and is experiencing hallucinations or delusions, talk with their care team.