Understanding the link between insulin resistance and cognition: a cross-sectional study conducted in an urban, South Indian cohort.

Abstract

Background: Recent research suggests that metabolic dysregulation caused by insulin resistance (IR) can have a negative impact on cognition. Therefore, the objective of this study is to explore the role of IR as an independent metabolic risk for decreased cognitive performance.

Methods: The study included 1072 non-demented participants aged 45 years and above were recruited from Tata Longitudinal Study of Aging (TLSA). Fasting insulin and blood glucose levels were collected during the baseline visit. HOMA-IR formula was used to calculate IR. Cognition was assessed using the COGNITO neuropsychological test battery. Generalized Linear Regression Model (GLM) was performed to find the relationship between IR category and COGNITO battery. The brain imaging was conducted using a 3 Tesla MRI system. The cortical volumes were acquired using Freesurfer software (v7.2.0) (Salgado et al. Arq Gastroenterol 47(2):165-169, 2010). Further, GLM analysis was performed for MRI variables.

Results: The estimated general prevalence of IR in our study is 56.3%. Model 1 suggested that IR is associated with reduced auditory attention (p = 0.014), and word comprehension (p = 0.043) tasks. Model 2 and 4 showed that there is an association with IR and poorerauditory attention (p = 0.015; p = 0.012) task. However, there was no significant association found in model 3. GLM analysis for MRI indicated that IR is associated with reduced brain volumes in left hemisphere like amygdala (p = 0.0012), inferior temporal lobe (p = 0.002), lateral orbitofrontal cortex (p = 0.005), superior temporal insula (p = 0.017), middle temporal lobe (p = 0.002), entorhinal (p = 0.049), and right hemisphere brain volumes like precuneus (p = 0.025), and insula (p = 0.002).

Conclusions: Our study findings conclude IR is significantly associated with poorer cognitive performance related to auditory attention. Furthermore, the study also revealed that IR is associated with decreased brain volumes in specific regions.