Physical exercise, IGF-1 and cognition A systematic review of experimental studies in the elderly

One of hypothetical mechanisms related to cognition is exercise-induced IGF-1. OBJECTIVE: The aim of this study was to analyze the effects of exercise on IGF-1 levels and cognition in the elderly. METHODS: The article searches were conducted on Pubmed, Web of Science, PsycINFO and Scielo databases and reviewed according to PRISMA guidelines. The inclusion criteria were: [1] original articles published up to 2017; [2] samples including elderly; [3] protocols including physical exercise; [4] longitudinal studies having exercise as main outcome; [5] assessment of IGF-1; [6] cognition assessment. RESULTS: Seven studies were included in this review. Three of the studies showed an exercise-induced increase in IGF-1; three found stable IGF-1 levels and one found a reduction in IGF-1; with and without improvement in cognition. CONCLUSION: Disparities in the type of physical exercise, protocols and samples under different conditions hinder the establishment of a consensus on IGF-1, cognition and physical exercise.