Dementia as a Consequence of Many Small, Unnoticed Strokes

Dementia can result from age-related damage to the white matter in the brain, known as leukoaraiosis or white matter hyperintensities. Here researchers look at the source of this damage:

Approximately 50 per cent of older individuals have evident white matter damage on their medical imaging scans. For most patients, these changes are harmless but when this damage is severe, it can cause impairment. Previous studies have already established that the more white matter disease there is in the brain, the more likely patients are to have symptoms of dementia such as cognitive impairment or changes in behaviour. What was not understood is why this white matter disease develops - the traditional assumption was that it might be the result of the natural aging process.

The researchers conducted an intensive study to observe the development of this white matter disease over a short period of time, rather than on an annual basis - the interval at which previous studies have performed repeat brain imaging. The study involved 5 patients with white matter disease undergoing detailed MRI scanning of their brains every week for 16 consecutive weeks. The weekly MRI scans revealed new tiny spots arising in the brain's white matter that were, based on their MRI appearance, characteristic of small new strokes (cerebral infarcts). The lesions had no symptoms but, with time, came to resemble the existing white matter disease in the subjects' brains. In the study's random sampling, the majority of subjects had this phenomenon: Tiny strokes occurring without symptoms, and developing into the kind of white matter disease that causes dementia.

"The findings suggest that the tiny, silent strokes are likely much more common than physicians previously appreciated, and these strokes are likely a cause of the age-related white matter disease that can lead to dementia. We don't yet know whether these small strokes are responsible only some or most of the white matter disease seen in older patients. But in those where it is the cause, the detection of white matter disease on brain imaging should trigger physicians to treat patients aggressively when managing stroke risk factors such as high blood pressure, diabetes, high cholesterol, cigarette smoking and lack of exercise not only to prevent further strokes, but also to reduce the development of cognitive impairment over time."

Link: http://www.uhn.ca/corporate/ForMedia/PressReleases/Pages/researchers_discover_possible_cause_dementia.aspx

Comments

My mom's doc just diagnosed thro an MRI this very thing. We just thought it was dementia, but most probably from the strokes.

She had none of the risk factors except lack of exercise. And that is sad because she was a great walker and exerciser thro her late 70's, then knee pain became so bad she quit all the walking, hiking and other activities she had done her entire life. So sad to see such a vibrant woman now needing help to potty.

Posted by: yvonne at November 7th, 2014 12:36 PM

After an early diagnosis of Alzheimer's - my mom was ultimately diagnosed with "vascular dementia" - the very disorder discussed. The progression of her dementia was different from Alzheimer's with a noticeable decline followed by a sometimes lengthy period of status quo etc. Once diagnosed correctly she was given medication that lessened the agitation and outbursts that had begun to occur without causing the over sedation that some of the Alzheimer's meds induced. We were told that meds typically given to Alzheimer's patients were completely wrong for someone suffering from this type of dementia - so diagnosis is important. My mom's dementia was advanced and she was in her 90's before we were able to get this diagnosis confirmed so it was too late to prevent or lessen the effects - but the distressing symptoms of irritation and anger in her last years (died at 95) were eased by the correct diagnosis and therefore the correct treatment. Perhaps imaging of seniors for earlier diagnosis and treatment could improve the outcome for many thus lessening the need for expensive round the clock care for some of us as we age.

Posted by: MJ at November 7th, 2014 1:10 PM

MJ,

What types of successful treatments were given to your mother after the correct diagnosis? Your description of your mother's condition sounds like that of my mother. Treatments seem to be depressingly limited for vascular dementia, so any insights you could offer would be very helpful and much appreciated. Thank you.

Posted by: CW at November 7th, 2014 4:36 PM

I'm glad this story has brought out these stories about vascular dementia and the importance of differential diagnosis: while we work to advance rejuvenation biotechnology to put an end to all this horror, it's vitally important for people who fall prey to dementia and their families understand the correct aetiology to get the right treatment.

Relatedly, it's important to understand that what is called "vascular dementia" is not the same phenomenon they're talking about in this research: although both involve strokes, "vascular dementia" is normally the result of one or more full-on strokes leading to neuronal death and impaired oxygen availability. The more subtle process of accumulating white matter hyperintensitites (driven, per this research, by very small "silent strokes") is a more subtle and global effect on the aging brain that affects a different range of cognitive function and contributes to both "normal" cognitive aging and both vascular dementia and AD.

Of course, these are idealized classifications: the reality is that everyone develops some level of Alzheimer's, Lewy body dementia, vascular dementia, and leukoaraiosis as s/he ages, and actual cases of clinical dementia are a mixture of all, with one predominating but all of them contributing to the terrifying, disabling, piteous wreck of a human mind.

For that reason, it's infuriating to read the press agent's (and probably the researchers') glib statement that "the traditional assumption was that it might be the result of the natural aging process," as if that were an explanation or would make it all right or inevitable, while Alzheimer's, leukoaraiosis, and strokes are something totally separate from "the natural aging process" and reasonable targets for intervention. We need to get it through people's heads that all of this mess is "part of the natural aging process." We have to stop allowing that phrase to turn off our brains and passively accept whatever the subject matter is, and realize that the only way we're going to tackle Alzheimer's, leukoaraiosis, and strokes — and cancer, heart disease, and macular degeneration — is to tackle the degenerative aging processes that drive them all.

Posted by: Michael at November 14th, 2014 12:11 PM

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