Adiposity hormones and dementia

Adipose tissue is an endocrine and paracrine organ that contributes to both metabolic and vascular homeostasis. Overweight and obesity due to excess adipose tissue, are cornerstones of vascular risk and increase risk for late-onset dementia. Vascular risk does not exist in isolation, and is accompanied by alterations in hormonal metabolism and metabolic syndromes. Thus, while vascular risk is highlighted as a primary mechanism for elevated dementia occurrence due to obesity, hormonal risk states may also precede or result from underlying dementia-related neuropathologies and direct neuronal toxicity. This is exemplified during the prodromal phase of dementia, as vascular and metabolic parameters decline in relation to dementia development, and potentially in a way that is different from 'normal' aging. In this review will be presented a review of the epidemiology of adiposity and dementia; adipose tissue biology; and two major hormones produced by adipose tissue, leptin and adiponectin, that interact directly with the brain. In addition, a synthesis related to other lines of supporting evidence for the role of adipose hormones in dementia will be provided. Understanding the role of adipose tissue in health of the brain is pivotal to a deeper understanding of dementia processes.