Two studies point way for stroke research

More Canadians are surviving severe stroke, but they are also experiencing poorer quality of life, according to a study published last month in the journal Stroke by UBC PhD student Jodi Edwards.

Meanwhile, Edwards’ lab mate, post-doctoral fellow Sean Meehan, has found that when learning a new movement post-stroke, the brain uses the prefrontal cortex – an area typically associated with cognition – to compensate for damage to motor regions of the brain. His study was published this April by the journal Human Brain Mapping.

The studies underscore the urgent need to develop rehabilitation strategies to help those who have survived stroke and point the way to do just that, says Lara Boyd, Canada Research Chair in Neurobiology of Motor Learning and supervisor to both Edwards and Meehan.

“Jodi’s study tells us that quality of life after stroke has decreased in the past decade. A potential reason for this decline is that while we’re good at rehabilitating patients who have suffered mild and moderately severe strokes, we have very little to offer the increasing number of Canadians who have survived a severe stroke,” says Boyd, an assistant professor in the UBC Department of Physical Therapy. “But Sean’s study is pointing to ways to make a major impact in post-stroke care.”

Edwards sourced data from public health surveys published by Statistics Canada between 1996 and 2005 – a decade that saw many significant advances in early acute stroke intervention – and analyzed stroke survivors’ self-assessment in eight quality-of-life attributes.

“Despite improvements in medical intervention, quality of life actually declined for Canadians who had suffered a stroke,” says Edwards, a Canadian Institutes of Health Research (CIHR) and Michael Smith Doctoral Scholar from the School of Population and Public Health and the Brain Behaviour Laboratory. “And the two areas of impairment that most impacted quality of life were motor and cognitive functions – which is in line with the most commonly identified residual deficits of severe strokes.”

“On the one hand, the findings are understandably discouraging for those who work with stroke patients on a daily basis,” says Edwards, who works closely with stroke neurologists and physical therapists at Vancouver General Hospital and will present her findings at the upcoming Canadian Stroke Congress in Quebec City.

“On the other hand, we’ve now identified two domains where we could make the most impact in devising rehabilitation strategies and potentially improve quality of life.”

Just a few feet from Edwards’ desk, Meehan, a CIHR and Michael Smith post-doctoral fellow, studied functional magnetic resonance imaging (fMRI) images from both healthy and post-stroke individuals and saw the remarkable way the brain rallied around a new challenge.

When performing a joystick tracking exercise, healthy participants demonstrated increased activity in the premotor cortex – an area typically associated with planning and learning movements.

In contrast, Meehan discovered that after stroke, people showed increased activity in a region of the brain associated with cognition, the prefrontal cortex, rather than the premotor areas.

“This shows us that the post-stroke brain can still learn motor skills, but that it’s using a different network to compensate for the damage,” says Meehan, whose study is the first to show the role of the prefrontal cortex in post-stroke motor learning. “This new information on how the brain compensates for damage suggests two potential strategies for rehabilitation: We could work on restoring the original brain function before the stroke occurred, or by promoting this new pathway.”

“The convergence of these findings from seemingly very divergent areas of research is telling us that the brain isn’t working in compartments – each area taking charge of certain functions that may be irrevocably damaged by injury or disease,” says Boyd, a member of the Brain Research Centre. “Rather, the different domains of the brain are inter-related and may work together to take on new challenges.

“This insight will go a long way to helping us devise rehabilitation strategies that will make the greatest positive impact.”

The Brain Research Centre

comprises more than 200 investigators with multidisciplinary expertise in neuroscience research ranging from the test tube, to the bedside, to industrial spin-offs. The Centre is a partnership

of UBC and Vancouver Coastal Health Research Institute. For more information, visit www.brain.ubc.ca.

Post-doctoral fellow Sean Meehan and PhD student Jodi Edwards have uncovered new information about quality of life after a stroke and how the brain responds to new challenges.