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Psychosis A broad medical term used to describe a loss of contact with reality that involves hallucinations and/or delusions. 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. Psychosis can vary from severe confusion (disordered thinking) to seeing things that aren’t there (hallucinationsSomething you see, hear, smell, taste or feel that is not actually there.) 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.

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.

About 20 to 30 percent of people with PD will experience visual hallucinations, and your risk increases the longer you live with PD.

Types of Hallucinations

  • Visual: Hallucinations in people with PD are usually visual. Common hallucinations include seeing animals or people, such as a furry creature running by or a deceased love one sitting in the room.
  • Auditory: Hearing voices or sounds that are not real is less common but is reported by a small percentage of people with PD.
  • Olfactory: Smelling an odor that is not related to an actual source is rare in PD.
  • Tactile: Feeling something imaginary, like bugs crawling on your skin, is rare in PD.
  • Gustatory: Sensing a bitter or abnormal taste in your mouth that has no source is rare in PD.

More about Hallucinations

  • Hallucinations are most often a side effect of medication and are not necessarily a sign of a decline in cognitive abilities. Most hallucinations experienced by people with PD are fleeting and non-threatening. However, in some cases hallucinations may become threatening or bothersome.
  • Although hallucinations can affect anyone taking medication to manage PD symptoms, they are more common in people who have problems with thinking or memory, or when under medical stress.
  • Visual hallucinations are more likely to occur in low light or low visibility situations. To reduce risk, increase lighting in particularly dark areas, such as hallways.
  • Hallucinations may occur in the peripheral vision (out of the corner of the eye), in the form of a flash of light, people or small animals such as cats or dogs. Images often disappears when the person looks more closely.
  • Sometimes people with PD have presence hallucinations — the feeling that someone is in the room with them or standing behind them. 
  • Some people are aware that hallucinations are occurring. This is called “retaining insightIn the context of hallucinations, when you recognize that what you are seeing or hearing is not real..” With insight, you might be able to create coping mechanisms. However, some people find them incredibly real, or may lose insight as the disease progresses.

Tips for Living with Hallucinations

It is important for people with PD to talk about hallucinations with their family and care team, because they are manageable and can be troublesome if not treated. Discuss all possible symptoms with your doctor, no matter how minor, rare or bizarre you may think they are.

  • Good lighting and stimulating activities in the evening can help keep hallucinations at bay.
  • While a hallucination is occurring, caregivers can help their loved one by reassuring them that they will be safe and validating their partner’s experience. For example, say, “I’ll take the cat outside” instead of arguing that there is no cat.

What Are Illusions?

IllusionsA distortion of sensory perception when you misinterpret real external stimuli, such as mistaking hats on a coat rack for heads. 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?

DelusionsFalse, fixed, idiosyncratic beliefs, not substantiated by sensory or objective evidence; a delusion is not deliberate and cannot be controlled. 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 eight percent 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.
  • All forms of delusions can be seen with PD, although delusions of jealousy and persecution (like paranoia A common type of delusion resulting in extreme distrust or suspicion.) 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 caregivers.
  • Paranoia can lead to medication noncompliance — a person refusing to take medications, believing they are poisonous or deadly.
  • Delusions can be associated with dementiaA term used to describe a group of brain disorders that cause a broad complex of symptoms such as disorientation, confusion, memory loss, impaired judgment and alterations in mood and personality.. As a result, people with delusions are often confused and extremely difficult to manage. In these cases, many caregivers require outside assistance.

Examples of Delusions in PD

  • 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 A feeling of nervousness, worried thoughts and physical distress., agitation, reports of abnormal or unusual symptoms, extreme concern regarding symptoms, frequent visits with the clinician.

What Causes Hallucinations and Delusions?

Medication, dementia and deliriumA state of altered awareness with agitation, hallucinations and confusion. 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.


Many PD medications can lead to symptoms of psychosis:

  • Classic PD medications like carbidopa-levodopa (Sinemet) and dopamine A chemical messenger (neurotransmitter) that regulates movement and emotions. agonists are designed to increase dopamine levels, improving motor symptoms. However, by boosting the dopamine supply, these medications can inadvertently cause serious emotional and behavioral changes.
  • Other medications used to treat PD can also cause these symptoms by lowering levels of acetylcholine A chemical messenger (neurotransmitter) in the striatum area of the brain. It is involved in many brain functions, such as memory and control of motor activity. It is believed that acetylcholine and dopamine maintain a delicate balance in the brain. Lack of dopamine in people with Parkinson’s disrupts this balance. Anticholinergic medications block acetylcholine., shifting its balance with dopamine. These medications include amantadine and anticholinergics Substances that block the neurotransmitter acetylcholine in the central and the peripheral nervous system; typically the main ingredient in over-the-counter sleep aids and many allergy medications (e.g., Benadryl). Trihexyphenidyl (formerly Artane), benztropine (Cogentin) and ethopropazine (Parsitan) are typical Parkinson’s medications in this class. (Artane and Cogentin). In addition to the prescription drugs, anticholinergics are typically the main ingredient in over-the-counter sleep aids and many allergy medications.


Dementia is a term used to describe a group of symptoms associated with a decline in memory and thinking. It is commonly associated with Alzheimer's disease A neurodegenerative disorder that results in loss of memory, thinking and language skills and behavioral changes. It is the most common form of dementia., but people with PD can also develop it.

  • Hallucinations and delusions can result from the basic chemical and physical changes that occur in the brain, regardless of other factors such as PD medications. This is most commonly seen in cases of PD with dementia.
  • If psychosis and dementia occur early in the disease process, doctors may consider a diagnosis of dementia with Lewy bodies (DLB) A progressive, neurodegenerative disease that shares symptoms of both Alzheimer’s disease and Parkinson’s. Unlike Parkinson’s disease dementia, cognitive symptoms are present before or within one year of noticing movement symptoms. The central features of DLB include progressive cognitive decline, changes in alertness and attention, visual hallucinations and parkinsonian motor symptoms such as slowness of movement, difficulty walking or rigidity..


Delirium is a reversible change in a person's level of attention and concentration.

  • Delirium usually develops over a short period of time (hours to days) and resolves following treatment of the underlying condition.
  • Signs of delirium include altered consciousness or awareness, disorganized thinking, unusual behavior and hallucinations.
  • Because there are so many symptoms, delirium can be confused with other conditions, such as dementia or drug-induced psychosis Certain drugs can lead to hallucinations and/or thought distortions. Should be considered before a diagnosis of Parkinson’s disease-associated psychosis is made..
  • To diagnose delirium, a person’s level of concentration or attention must go through a change.
  • People with Parkinson's have a higher risk of delirium when admitted to the hospital, due to the new settings for the procedure or surgery, which may be unrelated to their PD.

Common causes of delirium include:

  • Infection, such as urinary tract infection or pneumonia
  • Imbalance of sodium, potassium, calcium or other electrolytes
  • Stroke The sudden death of some brain cells due to a lack of oxygen when the blood flow to the brain is impaired by blockage or rupture of an artery to the brain.
  • Heart disease
  • Liver disease
  • Fever
  • Vitamin B12 deficiency
  • Head injury
  • Sensory changes, such as hearing loss and vision changes

In addition to medical conditions and changes, many commonly used drugs and chemicals can also cause delirium:

  • Anticholinergic medications: diphenhydramine hydrochloride (Benadryl®), trihexyphenidyl (Artane®), benztropine (Cogentin®), ranitidine (Zantac®) and oxybutynin (Ditropan®)
  • Narcotics containing codeine or morphine
  • Antibiotics
  • Nonsteroidal anti-inflammatory drugs (NSAIDS) including Aleve®, Motrin® and Advil ®
  • Insulin
  • Sedatives
  • Steroids
  • Anti-seizure medications
  • Alcohol
  • Recreational drugs

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 A mood disorder whose symptoms can include a persistent sad or empty mood, feelings of hopelessness or pessimism, irritability and loss of interest or pleasure in previously enjoyable activities.: 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 A dream state in which the dreams are very realistic, lifelike and disturbing at times.. 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 multi-step process that begins with talking to your health care 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: quetiapine (Seroquel®), clozapine (Clozaril®) and the newest agent, pimavanserin (Nuplazid®). They cause limited worsening of PD while treating hallucinations and delusions.


  • Pimavanserin was approved by the U.S. Food and Drug Administration (FDA) in 2016 specifically for the treatment of Parkinson's disease psychosis.
  • Unlike other antipsychotics, it does not block dopamine. It is a selective serotonin inverse agonist A type of drug that specifically targets serotonin receptors and makes them do the opposite of their normal function. Pimavanserin (Nuplazid) is an SSIA FDA-approved to treat Parkinson’s disease-associated psychosis., meaning it targets serotonin a neurotransmitter that regulates mood, body temperature, sleep, pain and appetite. receptors.


  • Clozapine (Clozaril) has been studied and proven effective in improving hallucinations and delusions in PD. However, due to a rare, yet serious side effect known as agranulocytosis ― a reduction in white blood cells that interferes with the body's ability to fight infection ― there is a tendency use this medication only if quetiapine is not tolerated or effective.
  • Anyone who takes clozapine is required to get weekly blood tests for the first six months, and every two weeks thereafter, to monitor white blood cell levels.


  • Quetiapine (Seroquel) has fewer side effects, but there is limited evidence for its efficacy in people with Parkinson’s.
  • It is most often prescribed to be taken just before going to bed because it may be mildly sedating.

*It is important to familiarize yourself with antipsychotic medications, as many 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 with someone who is experiencing a hallucination or delusion. 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. Chauncey Spears, Movement Disorders Fellow at the University of Florida, a Parkinson’s Foundation Center of Excellence.

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