B3317 - Visual Impairment in Psychosis Cause Consequence or Biomarker - 25/08/2020

B number: 
Principal applicant name: 
Claudia Cooper | University College London (United Kingdom)
Claudia Cooper, Joseph Hayes, Karoline Kuchenbaecker, Gemma Lewis, Natalie Shoham
Title of project: 
Visual Impairment in Psychosis: Cause, Consequence, or Biomarker?
Proposal summary: 

Eyesight Problems and Psychotic Illnesses: What’s the Link?
Psychotic illnesses affect just under 1% of people in England. Symptoms include hearing voices and experiencing confusing and distressing thoughts. These often begin in early adulthood, and can have a major effect on people’s lives.
People with psychotic illnesses seem to have more eyesight problems. We are not sure why, but it might be because:
• Possibility 1: Some people with psychotic illnesses find it harder to look after their health including their eyes, for example by going to the optician’s.
• Possibility 2: The same brain changes cause eyesight problems and psychotic illnesses.
• Possibility 3: Eyesight problems increase a person’s chances of having a psychotic illnesses.
I plan to look at which of these best explains the link between eyesight problems and psychosis. If people with psychosis have less eye care (possibility 1), we need to improve this. If possibility 2 is correct, eye research might hold the key to understanding more about the brain changes that cause psychosis. Or, if eyesight problems lead to psychosis, then improving eye health could be a way of preventing or reducing psychosis.
I will start by reviewing past research, to make sure I base my work on the most up-to-date information. I will then carry out research using two large datasets: UK Biobank and the Avon Longitudinal Study of Parents and Children (ALSPAC).
UK Biobank has information on over half a million 40 to 69-year-olds including questionnaires, eyesight tests and genetic tests.
ALSPAC has information on 14,500 UK families. The children have been followed up since before birth and will be 25.
I will look at UK Biobank and ALSPAC because older and younger people are most at risk of developing psychosis. In these datasets, I will see if people with short-sight genes have more psychotic illnesses. If so, this would be evidence that poor eyesight can lead to psychosis. Genes are present before birth, so I will know that they came before any psychotic illness began. I will also find out if genes for psychotic illnesses are linked with eyesight problems. This would suggest the reverse: that psychosis leads to poor eyesight.
I will also use a third, Israeli dataset. All Israeli 17-year-olds have health checks to decide if they can join the armed forces. I will use this data to find out if teenagers with eyesight problems are more likely to have a psychotic illness over the following years. If so, I will see what level of eyesight problems are associated with developing psychosis. This will allow me to test the theory that perfect eyesight and complete blindness both protect against psychosis, with moderate eyesight problems carrying the highest risk.
Throughout this research, I will chair a group every 6 months. It will include people with psychosis, people with eyesight problems, carers, charity members and doctors. We will discuss study findings and think about how to use them to improve the experiences of people with eyesight problems and psychosis. This will include plans to publicise findings, influence healthcare and plan new studies.
When the research is finished, I will tell healthcare professionals and researchers about the results at meetings and in journals. I will also write about them in publications read by people with mental health and eyesight problems. I will offer to present findings to public groups, through links with the Royal National Institute for the Blind (RNIB) and a forum of mental health service users.
People with eyesight problems and mental health service users helped to write this summary.

Impact of research: 
I will aim to publish findings in peer-reviewed journals. An implementation group will meet six-monthly, with particular emphasis on pathways to impact. They will advise on opportunities to disseminate findings via healthcare professionals, charities, and patient and carer groups, and develop plans to influence clinical practice, for example by responding to NICE and other relevant consultations. Visual impairment can be debilitating and is preventable in around 50% of cases. If we demonstrate evidence that psychosis increase risk of visual impairment (hypothesis 1), this would represent a major unmet need in people with psychosis; a health inequality that could and ought to be addressed. This may be different between younger people, who are most likely to experience a first episode of ‘non-organic’ psychosis associated with neurodevelopment, and older people, who are at higher risk of having psychotic symptoms associated with neurodegeneration. Older people are also more likely to have non-myopia causes of visual impairment than younger people. Studying the ophthalmic changes that lead to visual deterioration in psychosis could provide insights into the neurological processes underlying some psychotic illnesses, potentially informing the development of new treatments. It has been proposed, based on this hypothesis, that retinal nerve fibre layer thickness could be used as a diagnostic test for schizophrenia. If we demonstrate evidence supporting hypothesis 3, offering eye tests to people at high risk of or in the early stages of a psychotic illness could be a rational intervention to test. Training in visual processing has also been suggested as a possible therapeutic intervention for people with psychotic illnesses and visual impairment based on the hypothesis that visual impairment may contribute to its development.
Date proposal received: 
Wednesday, 12 August, 2020
Date proposal approved: 
Tuesday, 25 August, 2020
Mental health - Psychology, Psychiatry, Cognition, Mental health