High serum insulin, resistance impair cognition in long run
Serum insulin and insulin resistance may predict future impairment of cognitive performance in elderly adults without dementia, a recent study has found.
The study included 269 elderly adults without dementia (mean age 70.6±3.6 years; 61.3 percent female) who were part of the Cardiovascular Risk Factors, Aging and Dementia study. Global cognition, episodic memory, verbal expression, psychomotor speed and executive functioning were measured at baseline and at the 7-year follow-up.
In the initial multivariable-adjusted linear regression analysis, insulin resistance showed no correlations with any of the assessed domains of cognitive function.
However, excluding 19 participants who had incident dementia at follow-up, higher serum insulin levels at baseline correlated with a significantly worse performance in global cognition 7 years later (β, –0.054±0.02; p=0.031). The same was true for insulin resistance (β, –0.051±0.02; p=0.024).
Similarly, elevated baseline concentrations of serum insulin (β, –0.071±0.03; p=0.02) and greater insulin resistance (β, –0.070±0.03; p=0.013) were associated with poorer psychomotor speed. Analyses were adjusted for age, sex, education, baseline cognitive measures and the duration of follow-up.
Further controlling for body mass index, blood pressure, high-sensitivity C-reactive protein, stroke, smoking and a history of diabetes slightly attenuated the results but did not negate significance.
Baseline insulin remained significantly correlated with impaired global cognition at 7 years (β, –0.054±0.03; p=0.045), while higher insulin resistance at baseline continued to lead to long-term impairments in global cognition (β, –0.05±0.02; p=0.043) and psychomotor speed (β, –0.064±0.03; p=0.043).