Blood pressure, lipids may contribute to long-term dementia risk in type 2 diabetes
medwireNews: The onset of dementia in people with type 2 diabetes may be foreshadowed by elevated levels of some vascular risk factors 1 to 2 decades beforehand, say researchers.
At the time of dementia diagnosis, levels of systolic blood pressure (SBP), low-density lipoprotein (LDL) cholesterol, and BMI in these study participants were significantly lower than in people with type 2 diabetes who did not develop dementia.
Speaking at the virtual 2021 Diabetes UK Professional Conference, presenter Eszter Vamos (Imperial College London, UK) said this is in line with previous studies showing that levels of these risk factors “may start decreasing early in the preclinical stages of dementia,” and is likely due to reverse causation.
However, using data from the UK’s Clinical Practice Research Datalink, Vamos and team looked back at the medical histories of people with type 2 diabetes, and found that average SBP was higher in those who did versus did not develop dementia from approximately 17 to 11 years prior to their diagnosis date.
After this time, SBP declined more steeply in those who later developed dementia than in those who did not, so that it was lower from around 5 years prior to the time of diagnosis. There were no significant differences in the trajectory of diastolic BP between the two groups.
Average LDL cholesterol level was markedly higher in people who went on to develop dementia than in those who did not around 19 years beforehand, but then decreased and was slightly lower at the time of diagnosis.
There was little difference in levels or trajectories of total or high-density lipoprotein cholesterol between the groups over time.
BMI, on the other hand, was lower in people who did versus did not develop dementia at all times before the diagnosis, with the gap widening from around 11 years prior.
Glycemic measures were generally higher in people who developed dementia than those who did not, but Vamos noted that the absolute differences were small, the largest being a difference of approximately 5 mmol/mol in glycated hemoglobin seen 19 years prior to diagnosis, but this difference rapidly decreased over the following 2 years.
These data came from 23,319 people with type 2 diabetes who developed dementia, and 204,216 who did not. People with dementia were older, less likely to be male and more likely to be White, with a longer duration of diabetes and more comorbidities. The analyses accounted for these variables, plus others such as smoking status, economic status, and insulin use.
Vamos stressed that the study design could not demonstrate causation, but added that the results “confirm that dementia in type 2 diabetes may be related to the cumulative effects of high blood pressure [and] dyslipidemia, and reinforces the importance of early, comprehensive management of diabetes that might contribute to the prevention of dementia, besides the reduction of other diabetes-related complications.”
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