Understanding the mechanisms of visual hallucinations in Parkinson’s Disease

PhD Impact Story

Parkinson’s Disease (PD) is a very common neurodegenerative disorder – the second most common neurodegenerative disorder globally. In addition to motor problems such as tremor and slowness of movement, a large proportion of patients also experience other symptoms such as dementia and hallucinations, for which no effective treatment currently exists.

A PhD project by Marcella Montagnese has aimed to better understand the mechanisms underpinning visual hallucinations (i.e. seeing things that are not really there) in Parkinson’s Disease, especially in relation to cognitive decline and to dysfunctions in the visual system. She published her PhD in December 2022.

Marcella’s research is investigating three main areas:

  • Firstly, she has been using non-invasive neuroimaging tools such as functional MRI (fMRI) and electroencephalography (EEG) to map what brain differences exist between Parkinson’s patients who experience hallucinations and those who do not. Her work in this field has been accepted at international neuroscience conferences, both as selected DataBlitz talks at the Brain Conference 2022, as well as at the upcoming Organization for Human Brain Mapping Conference (OHBM).
  • Second, she has used meta-analytic tools on existent studies in the literature to evaluate whether there are differences in the performance of cognitive and visual tasks in Parkinson’s patients who hallucinate, and whether some of these tests could be used for early risk evaluation.
  • Finally, she is exploring potential new targets for treating these psychosis symptoms. This includes testing for possible beneficial effects of an already available cancer medication (Saracatinib) on brain activity associated with visual processing in a group of patients who have frequent hallucinations. This latter project is still ongoing due to the negative impact of COVID-19 on recruitment and testing of participants and will be completed in the next few years.

Having an impact now and in the future 

This research will contribute to a better understanding of both the neuro-biological and the cognitive differences that characterise those patients with Parkinson’s who do experience hallucinations. Doing so will allow researchers and clinicians to identify symptoms early on, develop more tailored treatment strategies for these patients, and improve the management of psychotic symptoms. This will have a positive impact on both the patients’ and their carers’ quality of life.

Marcella plans to continue her research into Parkinson’s disease, having recently published the first large-scale meta-analysis to date on the visual and cognitive profile of patients with Parkinson’s disease and hallucinations. She has also secured a prestigious NIHR SPARC award and has established a collaboration with experts in the field of neuroimaging at the University of Cambridge. There she is currently expanding her PhD work by combining network science and computational neuroscience approaches to better understand the neural underpinnings of Parkinson’s Disease Psychosis.



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