Prediabetes not independently tied to cognitive impairment after stroke
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The presence of type 2 diabetes was a significant risk factor for cognitive impairment following stroke, but investigators identified no association between prediabetes and cognitive function after stroke.
In a meta-analysis of studies from the STROKOG consortium published in Stroke, researchers stratified the data of 1,601 patients who experienced a stroke (mean age, 66 years; 26% white) into three groups: those with type 2 diabetes (fasting glucose 7 mmol/L), impaired fasting glucose or prediabetes (fasting glucose 6.1-6.9 mmol/L) and normal (fasting glucose < 6.1 mmol/L).
Worse cognitive outcomes
Investigators converted several neuropsychological tests to standardized adjusted z scores and found that, at 3 to 6 months after stroke, patients with type 2 diabetes had worse cognitive outcomes across all domains of cognition compared with patients with normal fasting glucose levels, including:
- global cognition (standard deviation [SD], 0.59; P < .001);
- attention and processing speed (SD, 0.54; P < .001);
- memory (SD, 0.21; P = .012);
- language (SD, 0.28; P = .004);
- perceptual motor (SD, 0.39; P = .001); and
- executive function (SD, 0.36; P = .004).
“Stroke remains a poorly recognized cause of dementia, and since stroke is at least partially preventable, this is one form of dementia that can be reduced with our current interventions,” Jessica W. Lo, MSc, of the Centre for Healthy Brain Ageing and the School of Psychiatry at the University of New South Wales, Australia, told Healio. “Further, diabetes increases the risk of stroke and also the risk of cognitive impairment and dementia in the setting of stroke. Diabetes therefore is another important target in the prevention of dementia, and the focus should be on the prediabetic stage to prevent its progression; and certainly, the status of prediabetes should be avoided if possible.”
Moreover, investigators found no significant difference between 3 to 6 month cognitive outcomes in patients with impaired fasting glucose and those with normal fasting glucose for global cognition (SD, 0.1; P = .55) or any other cognitive domain.
Conflicting evidence
“Currently, there is mounting evidence that diabetes is associated with poorer cognitive function; however, evidence regarding the association of prediabetes on cognitive function is conflicting,” Lo said in an interview. “We had assumed that stroke patients with prediabetes would have poorer cognitive function compared to those without, based on the idea that when you go from normal glucose levels to diabetes, there’s a continuum of risk. Additionally, the only study (to our knowledge) that examined this in a stroke population found an association. We were, therefore, surprised by the finding that those with prediabetes did not have poorer cognitive function compared to those without diabetes or prediabetes.”
The studies included in this meta-analysis featured cohorts from Australia, France, Korea, the Netherlands, Singapore and the U.S. Participants with stroke who were subsequently admitted to hospital and administered neuropsychological tests at 3 to 6 months after stroke were included in these studies. Patients with transient ischemic attack at recruitment were excluded from the final analysis.
“We are now processing follow-up data from our study cohorts and we will see if diabetes or prediabetes acquired before stroke are associated with cognitive impairment greater than 1 year after stroke and with cognitive decline over time,” Lo told Healio. “This analysis would form a small part of our project looking at cognitive decline in stroke patients.
“Ideally, we would like to examine how cognition is associated with change in diabetes status over time, and with diabetes acquired post-stroke,” Lo said in an interview. “However, since our analyses are retrospective, based on existing stroke cohorts from around the world, unfortunately, there is very limited follow-up data on diabetes.” – by Scott Buzby
Disclosure: Lo reports no relevant financial disclosures.
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