Serum insulin and cognitive performance in older adults: a longitudinal study
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CitationHooshmand, B. Rusanen, M. Ngandu, T. Leiviskä, J. Sindi, S. von Arnim, CAF. Falkai, P. Soininen, H. Tuomilehto, J. Kivipelto, M. (2019). Serum insulin and cognitive performance in older adults: a longitudinal study. American journal of medicine, 132 (3) , 367-373. 10.1016/j.amjmed.2018.11.013.
The aim of this study was to examine the association of serum glucose, insulin, and insulin resistance with cognitive functioning 7 years later in a longitudinal population-based study of Finnish older adults.
Serum glucose and insulin were measured at baseline in 269 dementia-free individuals aged 65-79 years, from the Cardiovascular Risk Factors, Aging, and Dementia (CAIDE) study. Insulin resistance was estimated with the homeostasis model assessment (HOMA-IR). Participants were reexamined 7 years later, and global cognition, episodic memory, executive functioning, verbal expression, and psychomotor speed were assessed, both at baseline and at follow-up. Multiple linear regression was used to investigate the associations with cognitive performance at follow-up, after adjusting for several potential confounders, including common vascular risk factors.
In the multivariable-adjusted linear regression models, no associations of insulin resistance with cognitive functioning were observed. After excluding 19 incident dementia cases, higher baseline HOMA-IR values were related to worse performance in global cognition (β [standard error (SE)] -.050 [0.02]; P = .043) and psychomotor speed (β [SE] -.064 [.03]; P = [.043]) 7 years later. Raised serum insulin levels were associated with lower scores on global cognition (β [SE] -.054 [.03]; P = .045) and tended to relate to poorer performance in psychomotor speed (β [SE] -.061 [.03]; P = .070).
Serum insulin and insulin resistance may be independent predictors of cognitive performance 7 years later in elderly individuals without dementia. Randomized controlled trials are needed to determine this issue.