- ‘Non-motor’ symptoms of Parkinson’s disease
- Hallucinations and delusions
- Does everyone with Parkinson’s experience hallucinations and delusions?
- What causes the symptoms of psychosis in Parkinson’s disease?
- Changing levels of neurotransmitters in the brain
- Effects of medication
- Dementia and Parkinson’s disease
- How are hallucinations and delusions experienced by people who have Parkinson’s disease treated?
- Antipsychotic medication
Parkinson’s disease has the main symptoms in posture and movement. This condition makes it difficult for a person to coordinate and control their muscles so they end up moving more rigidly and are much stiffer and slower. Another symptom to do with movement is a distinctive tremor or shaking of the hands or limbs. There are also other symptoms in addition to these that usually occur when the illness progresses. These symptoms include memory problems, problems with concentration, sleep problems (also including excessive day-time sleeping), anxiety, depression, fatigue and apathy. Those with Parkinson’s disease diagnosis occasionally experience psychosis symptoms too.
The symptoms of psychosis most frequently experienced by people with Parkinson’s disease are hallucinations – they see things that are not really there. These visual hallucinations might be relatives, friends, animals, buildings or places, often of things that mean something to them. Occasionally what they see in their hallucinations appears transparent or smaller.
People with Parkinson’s disease might also have other hallucinations – they might hear sounds or voices, or smell an unpleasant odour, for example.
Some understand that what they are experiencing is actually a hallucination but many perceive the experience to be real. Some of the hallucinations are pretty harmless but many can be very frightening to the person experiencing them and for their family members too.
Less common are delusions (irrational beliefs and thoughts). People might believe that their family is plotting against them or that someone is coming into their house and hiding their things. It might be that they think their wife or husband is having an affair. Delusions like this are obviously upsetting for the family, especially because they can make the person with the symptoms to be anxious, angry and suspicious.
Most people who have Parkinson’s disease don’t have psychosis symptoms. Studies show that the older generation is more likely to have delusions and hallucinations, as are those with Parkinson’s for a while (although delusions and hallucinations do appear at any point in the illness). Studies show that psychosis symptoms are much more likely to happen in those who experience sleep problems, dementia or depression. Research suggests that as much as 40% of Parkinson’s disease patients have hallucinations at some point in their illness.
Scientists are not sure why some Parkinson’s disease patients have delusions and hallucinations while others don’t. The physical Parkinson’s disease symptoms occur because of changes in neurotransmitters in the brain. Researchers believe that the changing levels of neurotransmitters might be key to the development of delusions and hallucinations, as well as other symptoms that are not to do with movement.
Psychosis symptoms could also be caused by medicines that have been prescribed for the motor symptoms of Parkinson’s disease.
Delusions and hallucinations can also occur when Parkinson’s sufferers get dementia.
Older people with Parkinson’s disease might occasionally experience an acute confusional state – delirium – when they have an infection like a chest infection or a urinary tract infection, or when they have a fever or are dehydrated. Delirium will cause delusions, visual hallucinations and confused thinking.
The motor symptoms of Parkinson’s disease are caused by brain cell death in the substantia nigra region of the brain. This is the part of the brain that is responsible for making dopamine, a neurotransmitter. Dopamine has the function of carrying messages around the brain that help us to coordinate and control movement. When more and more of these cells die, it becomes ever more difficult to control movement and muscles.
Dopamine is also responsible for helping the brain to focus, pay attention and remember things. When Parkinson’s develops, more cells that produce dopamine die leading people to find concentrating difficult and have memory problems. The cognitive problems might end up developing into dementia with Lewy bodies or ‘Parkinson’s dementia’. This is particularly prevalent when nerve cells beyond the substantia nigra begin to die.
Researchers believe that dopamine is involved in the creation of psychosis symptoms. The changes in dopamine production in the brain and the changes in other brain chemical levels linked to dopamine (including acetylcholine, a neurotransmitter) might contribute to delusions and hallucinations occurring in addition to the motor symptoms. The actual processes of this are not understood yet.
People with Parkinson’s are given medicines to increase the dopamine levels in the brain to help with their movement symptoms. Levodopa is one of the most commonly prescribed drugs for treating Parkinson’s. This converts into dopamine in the brain. Other medicines work by ‘tricking’ the brain into believing it is receiving dopamine by the stimulation of parts of the brain that are influenced by dopamine (this type of drug is called a dopamine agonist).
It is possible, therefore, that medicines prescribed for motor symptoms cause delusions and hallucinations and this is more common when the drug is taken for the very first time or when there is a dose increase.
However, medicines don’t always cause a person to have delusions of hallucinations – it depends on the medicine, the dose and how the individual patient reacts to it.
People who have Parkinson’s disease might develop ‘dementia with Lewy bodies’ or ‘Parkinson’s dementia’. Hallucinations are prevalent with this type of dementia.
Lewy bodies refers to the build-up of specific proteins in cells of the brain. When people have Parkinson’s, they are located in the dopamine-producing neurons. Scientists don’t know if they are linked to the death of cells that produce dopamine.
It is also possible for Lewy bodies to appear in other brain cells and in different areas of the brain. When these are found in neurons that are essential to memory and thinking, they are the cause of ‘dementia with Lewy bodies’.
People with this condition will regularly have intense and convincing hallucinations. They will see children, people and animals.
Researchers don’t yet understand why Lewy bodies (so-called after their identifying neurologist) happen or how damage is caused to contribute to the development of hallucinations and dementia symptoms.
If a person starts to have delusions or hallucinations, it is very important to seek help from a GP or a specialist in Parkinson’s. They will investigate thoroughly to source the trigger of these symptoms and the treatment depends on what is causing them. For example, if a person has a type of infection, the delusions and hallucinations could be because of delirium and antibiotics will clear the person’s infection and cause the delirium (delusions and hallucinations) to improve.
If a specialist thinks that a specific medication for Parkinson’s disease is the cause of psychosis symptoms, they might consider a change in medication, reduce the dosage or gradually stop the medication.
If the delusions and hallucinations are quite mild and don’t cause a person to be distressed, then they might not be treated. Nevertheless, specialists should provide people who have Parkinson’s and their loved ones information about its symptoms, why they occur and advice on dealing with them. Parkinson’s UK has leaflets that have tips for carers, family and friends.
A lot of people realise that their ‘visions’ aren’t real and can find a way to ‘switch them off’ or ignore them – for example, but turning up the lights more brightly.
If a person has severe psychosis symptoms, they might become stressful or troublesome for both the person and their loved ones. It could be that specialists provide antipsychotic medication.
Concern has been expressed by some researchers that specialists in Parkinson’s have very little experience in clozapine and this is a drug that is capable of causing a serious and life-threatening side effect agranulocytosis. This is very rare but it is responsible for slowing down or stopping white blood cell production, which fights infection. People who take this drug need regular blood tests to monitor their white blood cell level and this needs to be at least every week, to begin with.
A few trials of newer antipsychotics that are atypical have happened to discover their effectiveness in treating psychosis symptoms for Parkinson’s disease. These have shown olanzapine and risperidone make the motor symptoms worse in Parkinson’s.
Although clozapine is licenced for the treatment of Parkinson’s-induced psychotic symptoms, quetiapine is often prescribed off-licence by health professionals, as is aripiprazole, a new antipsychotic. In trials, quetiapine didn’t affect motor symptoms of Parkinson’s.