BCAT1 and Alzheimer disease: Furthermore, a large reduction in the concentration of valine has been detected in the cerebrospinal fluid (Basun et al., 1990) and plasma (González-domínguez et al., 2015; Toledo et al., 2017) of patients with AD patients, and the expression of hippocampal BCATc in patients with AD was increased by 28% compared with control brains (Hull et al., 2015).