More than tiredness - what's really behind post-stroke fatigue?

Over half of stroke victims live with a debilitating and often misunderstood condition called post-stroke fatigue.

Researchers at the University of Leeds, working with scientists at University College London (UCL), have identified that the clue to understanding it may be in the brain’s reduced ability to filter out distractions.

In this article, Dr Anna Kuppuswamy from the Faculty’s School of Biomedical Sciences, explains why this could offer new hope for both understanding the science and developing new treatments.

Fatigue is one of the most common and debilitating consequences of stroke. Over 50 per cent of stroke survivors report long-term fatigue, with some experiencing it years after the initial event. For many, this fatigue takes away their independence and their ability to return to work. Yet what causes such fatigue is still largely a mystery.

Our research, recently published in the British Psychological Society’s Journal of Neuropsychology, is a joint piece of work with Professor Nilli Lavie’s lab at University College London (UCL) where we have been investigating the role of the brain in generating long-term fatigue in stroke survivors.

How the brain reorganises after a stroke

After a stroke, large parts of the brain rewire to accommodate the loss of neural substrate directly affected by the stroke. While the direct impact of affected regions is well-studied, there is much to be understood regarding the impact of large-scale reorganisation of the brain.

Previous work has shown that when affected by a stroke there isn’t a particular region of the brain which consistently results in fatigue. This led us to propose that large-scale reorganisation - specifically in networks that underpin sensory processing - might be involved. This idea was inspired by patient self-reports of extreme sensory overload during their experience of fatigue. In this study, we investigated whether, in cases of high fatigue, the brain’s built-in coping mechanisms to avoid sensory overload are dysfunctional.

Image from an arts project showing a woman holding her head in a darkly lit room

Image: Taken from Ensnared, a collaborative arts and neuroscience project created by Sofie Layton in collaboration with stroke survivors, Dr Anna Kuppuswamy and Dr William De Doncker. Photograph by Stephen King.

Harder to tune out distractions

Our findings suggest that attention problems people experience after a stroke are not simply about difficulty concentrating. Instead, we have found that the brain appears to have trouble tuning out distractions, especially when tasks are more mentally demanding. In simple terms, normally the brain filters out irrelevant information so we can focus, but for people with post-stroke fatigue we see that this filtering systems doesn’t work as well.

This has significant implications. Chronic fatigue is often dismissed as trivial, or in the worst cases, not believed. This disbelief results in distress, isolation and long-term mood problems. A key reason for this lack of believability is the inability to find an organic cause for fatigue. Our study outcomes clearly demonstrate that chronic fatigue, when not explained by any other factor, is linked to the brain’s inability to suppress distractors, which could explain the lived experience of sensory overload, a classic feature of fatigue.

A biological base for post-stroke fatigue

Our findings have direct impact on how we understand fatigue, providing a biological basis for it and also have treatment implications. This research is relevant not only to stroke survivors but also to individuals with other conditions, involving chronic fatigue. Patients with long-standing fatigue, clinicians who treat fatigue, and employers supporting staff with long-term conditions may all benefit from this work.

We hope that by promoting this work, more patients, carers and clinicians we can continue to explore and understand this issue and work towards developing coping and treatment strategies.’