Depression, dementia, and psychosis are common in people with Parkinson disease. These conditions can affect how people with Parkinson disease cope and also have an effect on the quality of life for both patients and their caregivers.

Neurologists from the American Academy of Neurology (AAN) are doctors who treat diseases of the brain and nervous system. They recommend people with Parkinson disease be screened and treated if they show signs of depression or decline in their ability to think, reason, learn, or remember.

Experts in Parkinson disease, dementia, depression and psychosis reviewed all of the available studies about screening and treating depression, psychosis, and dementia in patients with Parkinson disease. They made suggestions that will help doctors, people with Parkinson disease, and their caregivers make choices in their care. In some cases, there were not enough published data for or against specific therapies.


Depression in people with Parkinson disease is common. Treating depression helps people with Parkinson disease effectively manage both conditions. Often depression is thought of as a normal reaction to living with Parkinson disease, but it is actually a symptom of the disease.

Patients, families and friends, and physicians should be aware of the warning signs. Depressed people will have several of the following symptoms:

  • Constant sad, anxious, or “empty” mood
  • Feelings of hopelessness, worthlessness, helplessness
  • Loss of interest in hobbies or activities
  • Decreased energy
  • Difficulty concentrating or making decisions
  • Insomnia or early-morning awakening
  • Appetite and/or weight changes
  • Thoughts of death or suicide
  • Restlessness, irritability

A doctor will want to know how long the person has felt this way. He or she will ask how severe the symptoms have been. A trained health care provider may use a depression screening test to make an accurate diagnosis. During a screen for depression, the patient answers a set of questions. The questions evaluate symptoms of depression and anxiety.

The experts found good evidence* that two screening tests, the Beck Depression Inventory and the Hamilton Depression Rating Scale, are probably useful in detecting depression in people with Parkinson disease. Another screening test, the Montgomery Asberg Depression Rating Scale, had weaker evidence* and is possibly useful in detecting depression in people with Parkinson disease.

A health care provider will prescribe a treatment based on the test results. The experts found weak evidence* that amitriptyline may be considered to treat depression in people with Parkinson disease. Amitriptyline is in a class of drugs called tricyclic antidepressants. These drugs have an effect on chemicals in the brain that affect mood and behavior. The side effects of some of these drugs can be harmful to people with Parkinson disease. Talk to your neurologist, mental health provider, or pharmacist about possible side effects. Some of the side effects include dry mouth, daytime drowsiness, and difficulty urinating—especially in men. There is not enough evidence* regarding the effectiveness of other treatments. Your doctor will use his or her judgement to determine use of these drugs.

Treatment for depression in people with Parkinson disease can be managed by your neurologist or a mental health professional who is in close communication with your neurologist.

Hallucinations and Delusions

Hallucinations consist of seeing or hearing things that are not really there. Examples are seeing animals, insects, children, or a shadow in the room. Over time, the hallucinations may become frightening or threatening. Delusions are fixed thoughts that are not based in the real world. Examples would be believing that nursing staff want to harm you, that your spouse is having an affair, or that people are stealing from you.

Hallucinations and delusions are dangerous because people may act on them and this can result in injury to themselves or those around them. It is also distressing to have delusions or threatening hallucinations for both the patient and the family.

Hallucinations and delusions are the result of the combination of Parkinson medications acting on previous personality traits or, more commonly, some degree of memory and thinking problems (dementia) associated with Parkinson disease.

At this point, there is no accurate screening test for hallucinations. If these symptoms are present, you or your care partner should tell your neurologist. Medications can be adjusted or new medications such as clozapine or quetiapine can control hallucinations and delusions.


Older people with Parkinson disease may develop dementia. It is more common in those over 70 years old. Dementia is a medical term referring to difficulties with recent memory (e.g., the person can’t remember what happened yesterday, but can remember events from years ago). Two terms used are Parkinson disease dementia and dementia with Lewy bodies. Most scientists believe they are the same thing. Signs of Parkinson disease dementia include changes in alertness, withdrawal, loss of problem-solving skills, and lack of flexibility in thinking (getting stuck on one topic). Trained doctors diagnose dementia using screening tests.

During a test for dementia, the patient answers a series of questions. These questions evaluate memory, problemsolving ability, attention span, and language skills. The experts found good evidence* that two tests are probably useful in detecting dementia with Parkinson disease, the Mini-Mental Status Examination (MMSE) and CAMCog.

The experts found good evidence* that two drugs may be considered to manage dementia in people with Parkinson disease. These drugs are rivastigmine and donepezil. Rivastigmine may be considered for the treatment of people with Parkinson disease and dementia with Lewy bodies Disease. The benefit with rivastigmine is small and tremor may worsen. Donepezil is possibly effective in improving thought processes in people with Parkinson disease and dementia, but the benefit is also small.

A person with Parkinson disease and dementia requires regular checkups with his or her doctor to ensure the therapies are working.

For Care Partners

Caring for a person with Parkinson disease and dementia is stressful. Care partners should talk to others about any frustrations they are experiencing. Talk to friends or family members, or join a support group for care partners. This can be very helpful. Care partners need to take care of themselves. If the care partner can’t take a break, he or she can burn out, develop mental and physical health problems, and become unable to care for the person with Parkinson disease.

Talk to your neurologist

Any change in mood or behavior; problem solving ability; ability to think, reason, or concentrate in a person with Parkinson disease is worth a visit to a neurologist or mental health professional. A doctor will recognize the symptoms of depression, dementia, or other mental health conditions.

This is an evidence-based educational service of the American Academy of Neurology. It is designed to provide members and patients with evidence- based guideline recommendations to assist with decision-making in patient care. It is based on an assessment of current scientific and clinical information, and is not intended to exclude any reasonable alternative methodologies. The AAN recognizes that specific patient care decisions are the prerogative of the patient and the physician caring for the patient, based on the circumstances involved.

*Note: After the experts review all of the published research studies they describe the strength of the evidence supporting each recommendation:

  • Strong evidence = More than one high-quality scientific study
  • Good evidence = At least one high-quality scientific study or two or more studies of a lesser quality
  • Weak evidence = The studies while favorable are weak in design or strength of the evidence
  • Not enough evidence = Either different studies have come to conflicting results or there are no studies of reasonable quality

Source: American Academy of Neurology.