Stroke patients who have difficulty paying attention to part of their visual field may perform better when offered a reward, a study by Imperial College London and Brunel University researchers has found.
Between a third and half of stroke patients suffer from spatial neglect - a disorder of visual attention that means they do not notice objects on one side of their field of view. In some cases, sufferers have been known to shave only one side of their face or leave half of a meal on their plate.
The new study found for the first time that patients with neglect did better in clinical tests when they were promised a financial reward. The findings point towards new behavioural therapies for stroke patients, and also highlight a system in the brain that can be targeted by drugs.
Dr Paresh Malhotra, from the Division of Brain Sciences at Imperial College London, who led the study, said: "There's been a lot of research recently on how reward can improve attention in healthy people. We wanted to see if performance would improve in patients with spatial neglect if you offer them a reward."
Ten patients with spatial neglect at Imperial College Healthcare NHS Trust were given a test that required them to circle images of coins on a sheet of paper with lots of similar-looking round objects. They were told they would get a pound for each coin they circled. They also performed a similar test with buttons instead of coins, and were told there was no reward for this test.
After their first visit, all the participants were given £15 worth of vouchers, although they were told that the value was determined by their performance in the coin test. They were given the same tests again on a later date, with a reward again promised for the coin test but not the button test. On the second visit, eight out of ten did better on the coin test. There was no improvement on the button test.
"Clearly we can't offer patients money, but the results suggest that other sorts of motivational stimuli might be useful in stroke rehab," Dr Malhotra said.
The researchers think the improvement in performance might be down to a brain chemical called dopamine, which has been found to improve attention in some patients with this condition. Many previous studies in healthy people and animals have found that dopamine levels rise when we anticipate a reward, such as food, sex or money. Dopamine is thought to make people feel motivated to behave in ways that bring about the reward.
The researchers did not measure dopamine levels in this study, but the two patients whose performance didn't improve when offered a reward had damage in a brain region called the striatum, which is recognised as a key area where dopamine is released. "There's a lot of work linking reward with dopamine, so another implication is that we are harnessing the brain's own dopamine system to bring about these effects," Dr Malhotra said.
The findings are published in the Journal of Neurology, Neurosurgery, and Psychiatry. The research was funded by the Academy of Medical Sciences, the Wellcome Trust, and the National Institute for Health Research Imperial Biomedical Research Centre.
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Notes to editors
1. Reference: P Malhotra et al. 'Reward modulates spatial neglect.' Journal of Neurology, Neurosurgery, and Psychiatry [date]
2. About Imperial College London
Consistently rated amongst the world's best universities, Imperial College London is a science-based institution with a reputation for excellence in teaching and research that attracts 14,000 students and 6,000 staff of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and business, delivering practical solutions that improve quality of life and the environment - underpinned by a dynamic enterprise culture.
Since its foundation in 1907, Imperial's contributions to society have included the discovery of penicillin, the development of holography and the foundations of fibre optics. This commitment to the application of research for the benefit of all continues today, with current focuses including interdisciplinary collaborations to improve global health, tackle climate change, develop sustainable sources of energy and address security challenges.
In 2007, Imperial College London and Imperial College Healthcare NHS Trust formed the UK's first Academic Health Science Centre. This unique partnership aims to improve the quality of life of patients and populations by taking new discoveries and translating them into new therapies as quickly as possible.
3. The Wellcome Trust is a global charitable foundation dedicated to achieving extraordinary improvements in human and animal health. It supports the brightest minds in biomedical research and the medical humanities. The Trust's breadth of support includes public engagement, education and the application of research to improve health. It is independent of both political and commercial interests. www.wellcome.ac.uk
4. The Academy of Medical Sciences is the independent body in the UK representing the diversity of medical science. Our mission is to promote medical science and its translation into benefits for society. The Academy's elected Fellows are the United Kingdom's leading medical scientists from hospitals, academia, industry and the public service. The Academy's Starter Grants scheme modest 'starter' funds to enable research active Clinical Lecturers to pursue their research work, gather preliminary data and so further strengthen their applications for longer-term fellowships and funding. www.acmesci.ac.uk
5. The National Institute for Health Research (NIHR) is funded by the Department of Health to improve the health and wealth of the nation through research. Since its establishment in April 2006, the NIHR has transformed research in the NHS. It has increased the volume of applied health research for the benefit of patients and the public, driven faster translation of basic science discoveries into tangible benefits for patients and the economy, and developed and supported the people who conduct and contribute to applied health research. The NIHR plays a key role in the Government's strategy for economic growth, attracting investment by the life-sciences industries through its world-class infrastructure for health research. Together, the NIHR people, programmes, centres of excellence and systems represent the most integrated health research system in the world. For further information, visit the NIHR website.
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