LEP and Alzheimer disease: PTP-1B, a regulator of insulin and leptin signalling that has been shown to be involved in multiple Alzheimer's disease processes,33 was moderately increased in both Dem-Alzheimer's disease (fold-change = 1.39, P = 0.037) and Dem-Other (fold-change = 1.39, P = 0.023) compared with CN individuals.