PREP and neurodegenerative disease: For instance, acylpeptide hydrolase is assumed to take part in the regulation of neuropeptide turnover, thus suggesting a new drug lead and plausible mechanism towards its effects in enhancing cognition and reducing neurodegeneration [62,63], while prolyl oligopeptidase (POP) is prominently expressed in the brain and has been implicated in neuroinflammatory events in neurodegenerative diseases.