Surviving a stroke can bring many long-term effects – including a much higher risk of dementia. But a study suggests that blood sugar may play a key role in that risk.
Loss of general thinking ability happened much faster in stroke survivors who had high blood glucose in the years after their health crisis, even after accounting for other things that might affect their brainpower, according to a study published in JAMA Network Open.
Those whose blood pressures or cholesterol were high after their stroke did not lose points on tests of thinking ability, also called global cognition, as quickly.
The researchers got the same results when they focused on people with a high genetic risk for dementia.
Led by researchers from Michigan Medicine, the University of Michigan’s academic medical center, the study is based on data from the STROKE COG study, which pooled, harmonized and analyzed data from four long-term studies of groups of people across four decades.
The study includes data from nearly 1,000 people who had detailed measurements of brain function and blood tests taken for years before and after they had a stroke – including 781 who had two or more brain function tests in the years after their stroke. Nearly 800 of the entire group also had a gene test for the APOE4 genetic variation that is associated with high risk for Alzheimer’s disease.
The researchers adjusted the data for differences in age, income, education, use of tobacco and alcohol, body mass index, heart disease and kidney function, and use of medications to treat high blood pressure, cholesterol and blood sugar. Post-stroke blood sugar measurements were taken an average of two years after their first stroke; about 20% of the study participants were taking diabetes medication before their stroke. None of the factors was linked to a faster loss of memory or executive function, which measures complex decision-making ability.