LDHA and Cognitive impairment: Shi et al. (2019) found that N-acetyl-isoputreanine is linked to the cognitive domain of processing speed in normal individuals. N-acetyl-isoputreanine is a byproduct of the enzymatic activity of aldehyde dehydrogenase (ALDH) and is produced through polyamine metabolism (Seiler, 1990). Our findings indicated a similar molecular mechanism of action between ALDH activity and polyamine metabolism, which has been linked to cognitive impairment (Shi et al., 2019; Fitzgerald et al., 2017; Grünblatt and Riederer, 2016).