ALDH2 and Alzheimer disease: Epidemiological studies of AD patients and analyses of ALDH–/– null mice, ALDH2*2 OE Tg mice (Figure 1) and ALDH2*2/*2 KI mice, all suggest that ALDH2 dysfunction may be a risk factor for AD, and that ethanol-induced aldehyde accumulation and its toxicity due to decreased ALDH2 activity may be a factor in AD pathogenesis.