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Optimising brain stimulation to help recovery from stroke

Project details

Professor Sven Bestmann
UCL Queen Square Institute of Neurology
Research area
Brain and spinal cord injury
Funding type
Project grant
Awarded in
September 2017


Better awareness of symptoms and improved treatments have helped reduce the number of people dying from stroke, leading to an increase in the number of stroke survivors. Unfortunately, many of these survivors are left with disabilities that limit their ability to live productive, independent lives.

Electrical brain stimulation is becoming widely used as a tool to help the brain recover following injury, but the absence of a clear mechanistic rationale for this tool has meant that it is being inconsistently applied, leading to mixed results. Professor Bestmann is using cutting edge mathematical and brain imaging techniques to introduce a consistent approach will help to unlock the full potential of brain stimulation to promote recovery after stroke.

Following rigorous assessment as part of our competitive project grant round, this project was selected for funding under our ‘acquired brain and spinal cord injury’ theme because our Scientific Advisory Panel felt that it would make an important contribution to knowledge in an important area, with high unmet need. With clear research questions and a simple design, the panel were confident that the research team would succeed in answering important questions about this kind of brain stimulation.

About stroke

A stroke occurs when the blood supply to part of the brain is cut off. This can cause catastrophic damage.

Whilst the number of UK deaths from strokes is going down, the lower mortality rates mean that more people are surviving stroke than ever before. There are an estimated 1.2 million stroke survivors in the UK today, more than half of whom are left with a life-limiting disability. Stroke-related disabilities include limb weakness, impaired mobility, and problems with speech, balance and co-ordination.

In addition to the huge personal impact, the impact on society is enormous. The economic burden of stroke in the UK is estimated at £9 billion a year – including health and social care costs, informal care, productivity losses and benefit payments. Two-thirds of working age survivors are unable to return to work.

Improving stroke recovery to enable survivors to live independent, productive lives is therefore a key goal.

Read more: Stroke

Can brain stimulation aid recovery from stroke?

Improving stroke recovery is a crucial clinical and scientific goal but our healthcare systems struggle to deliver enough rehabilitation in the time-frame required.

There is a substantial body of evidence that recovery can be enhanced through the use of electrical brain stimulation. It appears that this can increase the capacity of the brain to recover from the type of injury caused by stroke, and boost the effects of rehabilitation.  

Non-invasive electrical brain stimulation involves the delivery of a small electrical current to the brain using a pair of electrodes placed on the head.

Mixed results have been reported from clinical trials that have used the technique but, because there are a number of key mechanistic questions that have not yet been answered, the trials have no mechanistic rationale and are therefore unlikely to deliver consistent results. In simple terms, we do not know when and how to apply brain stimulation in order to achieve the best results:

  • When should brain stimulation be applied? Is it best early or late after stroke? Is it more effective within the first few weeks or several months afterwards? We know that the brain responds differently to early and late rehabilitation and therapy, but no systematic study exists to tell us when brain stimulation works best.
  • How should brain stimulation be applied? The effects of brain stimulation are variable, and this is partly due to the fact that we don’t know which brain regions are being stimulated, or how much electrical current is actually delivered. This has likely contributed to the overall ineffective use of brain stimulation. Recent developments allow better control over the amount of current that is delivered to the brain, and the team will exploit these developments to determine how the effects of brain stimulation are influenced by the time since stroke.

In this study, called 'ReCAPS: Re-opening the critical period for recovery after stroke', Professor Bestmann and colleagues at UCL are recruiting two groups of first-time stroke patients with impaired use of an arm and hand. The first group are ‘early’ patients, between 2 and 6 weeks post-stroke, and the second group are ‘late’ patients, more than six months post-stroke.

Brain stimulation will be applied to these patients in a dose-controlled manner, to ensure that the same dose of electrical current gets to the same target brain area in all patients. This means that when the research team compares the effects in the two groups of patients, they can be certain that any differences in response to brain stimulation between the two groups is due to the length of time since stroke, thereby telling us whether the therapy is more effective early or late after stroke.

For information about taking part in ReCAPS, click on the project logo above.

About the research team

Professor Bestmann has a long-standing track record in neuro-stimulation, human electrophysiology and movement control. He has pioneered several approaches for studying the impact of non-invasive brain stimulation on the brain.

He is working with Professor Nick Ward, a neurologist at the National Hospital for Neurology and Neurosurgery in London. Professor Ward directs the Upper Limb Neurorehabilitation Programme, the only dedicated clinic for stroke patients with upper limb impairment in the UK, which sees 220 patients annually.


If non-invasive brain stimulation does not appear to work, one explanation is that the current simply missed the target, but there has previously been no way of knowing whether this is the case. This has prevented attempts to test whether non-invasive brain stimulation could help stroke survivors by increasing the effectiveness of physiotherapy, for example.

This project will provide, for the first time, the basic understanding and insight for designing clinical trials to determine whether brain stimulation can enhance rehabilitation after stroke, both in the first few weeks as well as years after. In other words, it will enable us to determine the ‘who, how and when’ of non-invasive brain stimulation after stroke.

The use of non-invasive brain stimulation techniques for neurological rehabilitation has generated enormous interest in recent years. While such techniques might hold significant potential to improve rehabilitation, so far results have been disappointing. This is likely the result of limited understanding of the biological effects of the techniques, the influence of brain states at the time of stimulation, and a “one size fits all” approach to stimulation. The proposed project will address these important issues in a stroke population and should provide important and novel insights.
Without studies such as this, the field of therapeutic brain stimulation will continue to be characterised by studies lacking strong scientific rationale and result in more wasted research effort.”

- External reviewer

Related projects

Acquired brain and spinal cord injury (including stroke) is one of our current research priorities, reflecting the large unmet need in this area. Our aim is to fund research to advance understanding of how to promote repair of the brain and spinal cord following injury.

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