TGFB1 and early-onset autosomal dominant Alzheimer disease: Normally, TGFβ is involved in the self-renewal and maintenance of NSCs, but in the diseased brain, altered TGFβ levels are evident as in Alzheimer's disease where amyloid-beta plaques and tau tangles interfere with TGFβ signaling in NSCs, and reduced TGFβ signaling may lead to a decrease in the self-renewal capacity of NSCs, impairing the brain's ability to regenerate neurons and repair damaged neural tissue and contributing to the progressive loss of cognitive function (Meyers and Kessler 2017).