Increased peripheral insulin levels have been found to lead to increased cerebral levels of pro-inflammatory cytokines such as interleukin-1β (IL-1β), interleukin-6 (IL-6) and tumour necrosis factor-α (TNF-α), all of which have been reported to be elevated in AD and have been located in amyloid plaques and their related glial cells in AD patients [65]. Here, TNF is linked to Alzheimer disease.