Hyperinsulinemia, insulin resistance and cognitive decline in older cohort

Abstract

Objective: Type 2 diabetes has been recently recognized as an important risk factor for cognitive decline of patients with Alzheimer's disease (AD). But the roles of hyperinsulinemia (HI) and insulin resistance (IR) in the development of AD are still controversial. This study was designed to evaluate whether HI or IR influenced the cognitive functions of older cohort.

Methods: The cognitive functions of 328 consecutive elderly patients were evaluated with a battery of cognitive rating scales. Their fasting blood glucose (FBG) and fasting insulin (FINS) were analyzed and IR was calculated with modified-Homa. The cognitive scores in different groups and the correlation of cognitive functions with HI or IR were analyzed.

Results: In our study, there were 180 participants with HI and 148 without HI, and 192 with IR and 136 without IR. The participants with HI showed worse cognitive functions than those without HI in MMSE, MOCA, CDR, orientation, delayed memory, and attention/calculation domains. Similarly, the elderly with IR had lower cognitive scores than those without IR in MMSE, MOCA, CDR, GDS, orientation, delayed memory, and attention/calculation domains. The insulin levels and Homa IR had negative correlation with the scores of MMSE and delayed memory, not only in the model 1 adjusted for FBG and diabetes history, but also in the model 2 adjusted for all nine demographic characteristics.

Conclusion: HI and IR are important risk factors for cognitive decline of the elderly, especially for the dysfunctions in delayed memory domains.