Diabetic Theory in Anti-Alzheimer’s Drug Research and Development. Part 1: Therapeutic Potential of Antidiabetic Agents

: Alzheimer's disease (AD) is a chronic and progressive neurodegenerative disorder that affects over 46 million people worldwide. It is characterized by a decline in cognitive abilities, including memory and thinking skills. AD patients also suffer from behavioral and psychological symptoms of dementia of which depression is the most prevalent. Currently available drugs provide modest symptomatic relief and do not reduce pathological hallmarks (senile plaques and neurofibrillary tangles) and neuroinflammation, both of which are integral parts of AD. Studies suggest that AD is a type of diabetes manifested in the brain. Although AD and diabetes are currently classified as separate disease entities, they share common pathophysiological mechanisms. One of them is an increased level of cytokines involved in the inflammation and the regulation of metabolic, regenerative, and neural processes. The purpose of this review was to update the most recent reports on the discovery and development of antidiabetic agents as promising drugs for the symptomatic and disease-modifying treatment of AD. We collected the results of in vitro and in vivo studies, and recent reports from clinical trials suggesting the utility of antidiabetic agents in memory-enhancing therapy of AD. Their beneficial effects on chronic neuroinflammation, pathological hallmarks, and neuropsychiatric symptoms co-occurring with cognitive deficits are also presented. Antidiabetic agents refer to the diabetic and inflammatory hypotheses of AD and provide hope to find an effective drug for comprehensive therapy of the disease.