A systematic literature review of the effect of insulin sensitizers on the cognitive symptoms of Alzheimer's Disease in transgenic mice

Clinical implication: Alzheimer's Disease (AD) presents as a gradual decline in cognitive function, with its characteristic pathology consisting of Amyloid beta (A beta) accumulation and hyperphosphorylated tau. Impaired insulin signalling was recently found in the brain in AD, and shown to increase AD pathology. Similar insulin resistance is found in type 2 diabetes and is currently treated with insulin sensitizers (IS). Aims and method: The aim of this literature review was to evaluate whether IS could effectively reduce AD's characteristic pathology and symptoms in models of AD in transgenic mice. The efficacy of an IS (Metformin, Rosiglitazone or Pioglitazone) at improving each characteristic in transgenic mice was evaluated. Results: A variety of cognitive tests and measures of pathology were utilized to assess these outcomes, hindering comparison. Improvements in cognition, learning and A beta pathology were demonstrated by some papers, and all papers reported a decrease in tau phosphorylation, but no effect on total tau levels.