Prevention of Stroke and Prevention of Dementia Overlap

Aging is a process in which a smaller number of mechanisms produce a larger range of consequences. This is true at the start of the chain of cause and effect, in which cell and tissue damage outlined in the SENS rejuvenation research programs produces a large range of secondary dysfunctions. It is also true further along the chain, where researchers observe diverse age-related diseases to share overlapping sets of common proximate causes. You might consider aging as a spreading tree of problems, the number of possible classes of dysfunction expanding dramatically at each layer of cause and effect.

This is characteristic of any simple cause of damage operating in a complex system – think of rust in an ornate metal structure standing upon many legs, for example. It might ultimately fall apart in any number of ways, but rust is a very simple process. It is far easier to handle the rust than to try to prop things up in other ways while letting the rust continue to progress. So too with aging: the easiest and most cost-effective way forward is to target and repair the root causes of aging, not the later problems. The further along the chain of consequences, the more complex the picture and the less effective the solutions. Still, any attempt to reduce the impact at any stage should produce benefits to more than one measure of aging or age-related disease, as illustrated here:

A stroke prevention strategy appears to be having an unexpected, beneficial side effect: a reduction also in the incidence of dementia among older seniors. A new paper shows there’s been a decade-long drop in new diagnoses of both stroke and dementia in the most at-risk group ­­- those who are 80 or older. “Some have said we’re on the cusp of an epidemic of dementia as the population ages. What this data suggests is that by successfully fighting off the risks of stroke – with a healthy diet, exercise, a tobacco-free life and high blood-pressure medication where needed – we can also curtail the incidence of some dementias.”

This is the first study that has looked at the demographics of both stroke and dementia across Ontario since the province pioneered Canada’s first stroke prevention strategy in 2000. That strategy includes more health centres able to manage stroke, more community and physician supports, better use of hypertensive mediation and well-promoted lifestyle changes to reduce risks. Five provinces have stroke strategies and five do not. “We have systems in place for stroke prevention and our hypothesis is that any studies looking at stroke prevention should also investigate dementia prevention. It’s a good-news story for Ontario and it could be a good-news story elsewhere.”

Most strokes are caused by the restriction or constriction of blood flow to the brain. Vascular dementia also develops as blood supply to the brain is reduced. Someone who has had a stroke is twice as likely to develop dementia. Someone who has had a diagnosis of stroke has also likely had several prior “silent” strokes that may have affected a patient’s cognitive abilities. Specifically, the study data shows that the incidence of new stroke diagnosis among highest-risk group, people aged 80-plus, dropped by 37.9 per cent in a span of a little more than a decade. During the same timeframe, the incidence of dementia diagnoses in that age group fell by 15.4 per cent. “As clinicians and researchers, we are still trying to get a handle on how to reduce a person’s chances of dementia late in life. Some we can’t influence – yet – but here is a pretty clear indication that we can take specific definitive steps to reduce our chances of dementia related to vascular disease.”




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