- Lower cognitive test scores in areas such as memory and processing speed could indicate an increased risk of stroke, a new study finds.
- A previous silent stroke could affect cognitive function, though more research is necessary to determine how much it increases future stroke risk.
- Experts advise that it’s too early to recommend cognitive testing as a routine part of stroke risk assessment.
Stroke occurs every 40 seconds in the United States, according to the Centers for Disease Control and Prevention (CDC).
While strokes can occur at any age, risk increases with age. Having a stroke at a later age increases the risk of hospitalization and mortality.
A new observational study published in September in the Journal of the American Heart Association examined whether adults ages 60 to 69 with lower cognitive test scores were more likely to experience stroke later in life.
The researchers found that stroke was more likely to occur in those with reduced memory and quickness in processing information.
The researchers found that participants ages 60 to 69 years who scored lower on certain cognitive tests had up to an 86% increased risk of stroke.
The study followed 4,912 participants, among whom 3,094 were ages 60 to 69 years. Participants had no prior dementia, stroke, or transient ischemic attack (TIA). After an average follow‐up time of 12.3 years, 572 of the 4912 participants experienced a stroke.
The researchers determined the following in participants aged 60 to 69 years:
- 86% higher risk of stroke in those with lower overall thinking ability
- 68% higher risk of stroke in those with reduced episodic memory
- 66% higher risk of stroke in those with slower information processing.
Among all participants, there was no increase in stroke for those with lower scores compared with those in the mid-scoring group for verbal fluency and selected components of executive function.
The researchers did not find any significant associations in participants ages 70 and older after adjusting for health and lifestyle factors, such as smoking status, alcohol consumption, physical activity levels, and conditions such as diabetes and ischemic heart disease.
Derk W Krieger, MD, PhD, Professor of Neurology and Consultant Neurologist at Re:Cognition Health, spoke with Medical News Today about these findings.
“The age-specific finding may reflect the period when subclinical cerebrovascular disease becomes sufficiently prevalent to affect cognition, while cognitive impairment is still relatively sensitive to vascular brain injury rather than advanced age alone,” said Krieger, who was not involved in the study.
“The stronger association with memory and processing speed is biologically plausible because these functions depend on distributed neural and white-matter networks that are vulnerable to small-vessel disease and silent cerebrovascular injury,” he added.
“In contrast, verbal fluency and executive function are more influenced by education, language, cognitive reserve, and compensatory mechanisms,” he explained.
The researchers suggest that individuals with lower cognitive scores might have had more silent strokes — strokes that do not cause any obvious symptoms — than those with higher scores.
“I think this is very plausible. Silent cerebral infarctions and small-vessel disease can occur without obvious stroke symptoms but may still affect cognitive function,” Christopher Yi, MD, board certified vascular surgeon at MemorialCare Orange Coast Medical Center in Fountain Valley, CA, told MNT.
“These changes could therefore represent underlying vascular disease that also increases the risk of a future clinical stroke. However, this study did not use MRI to confirm that mechanism,” Yi, who was not involved in the study, added.
Krieger agreed that it’s “plausible” that individuals with lower cognitive scores may have experienced more silent cerebrovascular events, and that “it remains unproven unless supported by neuroimaging or longitudinal evidence.”
The study highlights shared factors that increase the risk of both cognitive impairment and stroke, including:
Yi told MNT that the shared risk factors could explain the association between cognitive function and stroke.
“Hypertension, diabetes, smoking, and physical inactivity can damage the blood vessels supplying the brain and contribute to both cognitive decline and stroke,” Yi explained.
“Importantly, the association persisted in the 60 to 69 group even after adjusting for many of these risk factors, suggesting they do not completely explain the findings [of the study],” he added.
- blood pressure
- blood sugar
- body mass index (BMI)
- blood cholesterol
- physical activity
- tobacco use
- typical diet
- existing conditions, such as diabetes and atrial fibrillation
- personal family history of stroke, TIA, or heart attack.
The study authors suggest that cognitive testing could be “an important screening tool” for future stroke in “younger older adults.”
Krieger cautioned that “cognitive testing should not yet be considered a routine component of stroke-risk assessment. This would require replication, demonstration of predictive value beyond established vascular risk scores, and evidence that acting on cognitive-test results improves clinical outcomes.”
Yi agreed that “it is too early to recommend cognitive testing specifically for stroke prediction. Future studies will need to determine whether cognitive testing adds meaningful information beyond established risk factors such as hypertension, diabetes, smoking, cholesterol, and atrial fibrillation.”
He added “it may eventually be most useful when combined with imaging or other biomarkers.”
Yi concluded that “[t]he main takeaway is that brain health and vascular health are closely connected. […] However, this study demonstrates an association and does not prove that lower cognitive function itself causes stroke.”
