CHAT and Alzheimer disease: For example, AD-related animal studies of reversible cholinergic changes have demonstrated that the intracerebroventricular administration of AF64A to induce cholinergic toxicity resulted in decreased ChAT activity and increased AChE activity in the hippocampus and septal regions of young rats (2, 4, and 12 months), whereas older rats, aged 22 months, showed no changes in ChAT and AChE activity (El Tamer et al., 1992, 1996).