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Psychosis in Parkinson’s - why it happens to your patients and how you can treat it

02 Jul 2020 19:15 - 20:30

Please note that all session and slide content are the views of the Speakers, not the Parkinson’s Academy. The content of the recording is the speaker’s personal opinion at the time of recording. Due to the everchanging situation, advice given at the time of recording is subject to change.


Many people with Parkinson’s disease experience symptoms of psychosis, including hallucinations and delusions.

Dealing with these issues is extremely difficult, not least because everyone presents differently and limited treatment options exist, said the panel.

What is psychosis?

Dr Ross Dunne explained that psychosis was related to a person’s perception of themselves and the world around them. It involves seeing patterns in the world and jumping to conclusions about what they mean.

How does it affect people with Parkinson’s?

Dr Christine Taylor said people presented in many different ways, and describing psychosis as a sliding scale.

“It can be very, very complex. One of the things that I’ve found most helpful in clinical practice is to have in my head a model called the neuro-psychiatric slippery slope,” she said.

“People might present initially with things like reduced sleep pattern, then start to get daytime somnolence. The next step would be if they had illusions, but still had insight about them, or some perceptual abnormalities.

“Moving on from there it might slide down into them starting to get more prominent or REM sleep issues. And then we move on to more full-blown psychotic symptoms, such as hallucinations and delusions.”

Dr Rimona Weil said her patients tended to experience visual hallucinations or misperceptions that worsened over time.

“People might make a mistake. They might see a pile of clothes on the floor and, just for a minute, think it’s a dog, or a leaf in the garden that they think is a bird.

“But then, as the disease progresses, they start to be more complex delusions or hallucinations, where there’s perception of an object in the absence of anything else. That’s when people start describing seeing children or people,” she said.

People may also experience:

  • a “sense of presence”, where they, for example, walk into an empty room and think someone is there
  • auditory hallucinations. While these are not common in Parkinson’s, they sometime occur as “soundtracks” to a visual hallucination
  • motion freezing, such as not being able to turn over in bed or a feeling that someone is holding them in place
  • Othello syndrome, or delusions of infidelity, is quite common and can have a significant impact on relationships. The delusions usually centre on one or more named person, and can drive the person with Parkinson’s to obsessively question their partner, check their phone etc.
  • feelings that the person’s partner is an imposter or has been replaced
  • delusions of theft
  • people thinking their home is not their home

Talking psychosis

The panel agreed it was important to give patients the opportunity to talk about any psychosis symptoms they may be having – but that it wasn’t always easy to do so within a routine consultation.

“Eliciting these symptoms from people is all about normalising them. When you start explaining Parkinson’s to people, it’s often seen as a disease of shaking and slowness, so when these neuropsychiatric consequences appear, they think something else has happened to them,” said Ross.

“It’s really important to put this into the context of Parkinson’s for people so that they are not outrageously frightened.”

Their tips included:

  • say “sometimes people with Parkinson’s have hallucinations or visions”
  • say “it wouldn’t be unusual for you to experience X, Y or Z”
  • ask “do you ever see things that are not there?” Carers may be able to help answer this question if the patient does not remember
  • ask “do you have any problems with your eyes?” to start a conversation about vision

It can help to explain why it happens, Ross said, if the patient shows an interest.

“I say your brain is constantly trying to fill in the gaps in your vision to make a sensible picture of the world. It’s like you’ve got a jigsaw with missing pieces, and when your brain tries to fill them in, you get illusions, delusions, and hallucinations,” said Ross.

When to treat

All agreed that the keys to making a decision to treat were insight and distress.

Referring back to the neuro-psychiatric slippery slope, Christine said those at the top of the scale were not usually distressed by the symptoms and still had some insight into them. In these cases, educating them and their carers on what was happening was usually enough.

“But as you get further down that scale, things start to become more problematic. When I’m speaking to patients, I’m thinking about where they are on the scale. Are we getting to the point where this is impacting on quality of life and are they losing their insight?”, she said.

Sometimes, healthcare teams can work with carers to implement simple strategies.

“I had a patient who was so convinced he wasn’t in his right home that the family used to take him for a drive around the village, then come back and say ‘we are home’,” said Dr Neil Archibald.

“I had a patient who sometimes thought his wife was a different person. She would say ‘Oh Deborah’s not here, I’ll go get her’, leave the room and them back in again as Deborah. Fighting the delusion head on just doesn’t work,” Rimona added.

How to treat

Before initiating treatment, healthcare professionals should always try to manage expectations, the panel agreed.

Ross said: “I often say to people, if we can get this to be 20% better that it is at the moment, would that be an acceptable level of improvement for you?”

Christine explained that she would:

  • review and optimise medications
  • exclude the possibility of delirium
  • make sure any comorbidities are under control
  • consider occupational therapy – sometimes things like patterned curtains or even dim lightbulbs can trigger hallucinations
  • provide education on how and why the symptoms are occurring
  • talk about ‘reality testing’ strategies – i.e. asking someone else if they can see what you can see
  • talk about the importance of good sleep hygiene and healthy lifestyles

Anti-psychotics and cognitive enhancers may help in some people, but not all, the panel agreed. As such pharmacological treatment should be approached on a case by case basis, they said.


Sykes, D.A., Moore, H., Stott, L. et al. Extrapyramidal side effects of antipsychotics are linked to their association kinetics at dopamine D2 receptors. Nat Commun 8, 763 (2017)


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