Insulin‐growth factor 1 (IGF‐1) in older adults with the concomitant presence of Alzheimer’s disease and type 2 diabetes mellitus

Abstract

AbstractBackgroundAlzheimer’s disease (AD) may be related to changes in insulin pathways, suggesting that individuals with type 2 diabetes mellitus (T2DM) are more likely to develop AD compared to healthy individuals. Insulin plays an important role in the mechanisms related to brain activity, especially in the formation of memories. Given the similarity between insulin‐like growth factor (IGF‐1) and insulin itself, this molecule has the ability to bind to the insulin receptor, but with low affinity. In addition to the brain, IGF‐1 is present in several tissues, acting as a mediator of physiological responses related to neuronal protection against toxicity caused by glucose deprivation and oxidative stress, in addition to playing an important role in apoptosis, cell proliferation and differentiation. In vitro studies have demonstrated the potential that this protein has to decrease tau protein hyperphosphorylation, one of the pathological hallmarks of AD. Moreover, in response to neuronal damage, IGF‐1 promotes neurogenesis and synaptogenesis.MethodThis is a cross‐sectional study, based on the assumptions of quantitative research, approved by the Ethics Committee of Federal University of São Carlos, SP, Brazil (CAAE: 12968413.1.0000.5504). It has been developed with a sample of 36 participants aged over 60 years, users of health services in the municipality. Specific inclusion and exclusion criteria and the MMSE and CDR cognitive assessment instruments were applied to participants from all groups. Quantification of IGF‐1 plasma levels was performed using the ELISA technique (Enzyme‐Linked Immunosorbent Assay).ResultHigher plasma levels of IGF‐1 were found in older adults with AD and concomitant T2DM when compared with older adults with diabetes (T2DM) (p = 0.0167) and healthy participants (p = 0.0003).ConclusionThe increase in IGF‐1 levels in plasma of older adults with AD+T2DM and T2DM groups may indicate an initial compensatory response against neuronal damage in the elderly with both diseases or T2DM. The findings and conclusions of the present study are exploratory, and further studies with larger sample sizes are needed to draw a firm conclusion.