Research confirms stroke associated with accelerated cognitive decline

Globally, stroke is one of the leading causes of disability and the World Stroke Organisation projects that incidents of stroke will continue to increase into the future.

The link between stroke and dementia is well established, however new research out of the UNSW has shown that stroke is associated with "acute and accelerated long-term cognitive decline in older stroke survivors."

The Centre for Healthy Brain Ageing (CHeBA) was able to map the trajectory of cognitive decline after the first incident of stroke in 14 international Cohort Studies of Memory in an International Consortium (COSMIC) study of older people, spanning 11 countries and equating to over 20,000 participants.

Research lead and biostatistician research associate Jess Lo points out that both stroke and vascular dementia are caused by a reduction in blood flow to the brain and although vascular dementia is the second most common type of the disease behind Alzheimer's, it is not equally studied.

“Although we do experience changes to our brain functioning over time and as we age, certain medical conditions can potentially speed up these changes, which may lead to cognitive impairment or dementia,” Ms Lo said.

“We wanted to understand exactly how stroke affects cognitive abilities such as thinking, memory and decision-making, and what the impacts are both short and long term.

“By analysing [the participants'] cognitive abilities over several assessment time points before and after stroke, we mapped out the course of changes in their thinking and memory over the periods before and after stroke, and therefore, were able to determine the changes in cognitive ability due to a stroke."

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Study participants were an average age of 73 years old, and all individuals showed some moderate signs of cognitive decline prior to experiencing a stroke. However, key to CHeBA's findings was the identification of a "significant immediate drop in cognitive performance, followed by a gradual long-term decline" at a faster rate than that which was seen pre-stroke.

Study senior author and co-director of CHeBA Professor Perminder Sachdev said the research also helped to identify risk factors for dementia, as participants who were smokers, had diabetes, hypertension, high cholesterol, cardiovascular disease, experienced depression, or were carriers of the APOE4 gene (the strongest risk factor gene for Alzheimer's disease) were declining cognitively at a much faster before any incident of stroke.

“Our findings can help clinicians better plan for the ongoing needs of stroke survivors who are at risk of disability and a lower quality of life,” Professor Sachdev said.

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