Western researchers find link between brain lesions, cognitive decline

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Western University researchers are zeroing in on a potential “canary in the coal mine” of mental decline and working on a blood test to screen for the troubling signal in the brain.

The research team says a common brain lesion in older adults could be used to predict cognitive decline and identify patients at highest risk for developing dementia, giving doctors a chance to start treatment before it’s too late.

“Dementia can be a really disheartening diagnosis for people,” said Austyn Roseborough, a physician and doctoral candidate in anatomy and cell biology, who led the research.

“If we can say to someone 10 years earlier that there’s some red flags in their brain, we can identify people who are suitable for clinical trials or who might respond well to therapeutics.”

Brain lesions are tissues that have been damaged by injury or disease. Western researchers analyzed a specific kind of brain lesion, white matter hyperintensities, that show up as light blotches on an MRI.

These white matter hyperintensities are present in the brains of up to 60 per cent of adults 50 and older, though in varying numbers and severity. People with the lesions may be completely asymptomatic, at least at first, Roseborough said.

“These lesions have been known about for a long time, but because they’re so common, they’re hard to interpret and they’re often written off,” Roseborough said Wednesday.

“As we research them, we’re realizing they aren’t benign. This is a point people who do research in this field have been trying to get across for some time, but it’s hard to with one study in isolation. By doing a larger review of what’s out there, we’re able to synthesize the information in a better way.”

The Western team analyzed several studies on the long-term impact of these white matter lesions in particular groups including people with mild cognitive impairment, Alzheimer’s disease and patients who had suffered a stroke.

In all the groups, having the lesions predicted worse mental outcomes and faster rates of cognitive decline, the study said.

The link between future mental decline and white matter hyperintensities was strongest in people with existing cognitive impairment or a history of stroke.

Stroke patients with severe white matter lesions were very likely to see their mental functioning decline anywhere from six months to five years post-stroke, the study said. The group was also at a heightened risk of seeing that decline convert to dementia.

While an MRI would identify the white matter lesions in at-risk people, Roseborough knows it’s not feasible to offer the intensive, in-demand diagnostic imaging to wide swaths of the population.

She now is looking for markers in the blood for white matter hyperintensities. Finding a blood-based signal would mean doctors could use a blood test instead of a brain scan to screen patients for the worrisome lesions.

“Blood-based biomarkers that show changes in white matter hyperintensities could be a predictor of danger 20, 30 or even 40 years down the road,” anatomy and cell biology professor Shawn Whitehead said in a statement.

“The whole idea here is that if I have these things happening in my brain that will predict dementia years from now, I can’t do anything about it unless I know it.”

The study is published in Alzheimer’s and Dementia: The Journal of the Alzheimer’s Association.

jbieman@postmedia.com

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