Aβ: amyloid beta; AβPP: amyloid-β protein precursor; AChE: acetylcholinesterase; AD: Alzheimer's disease; CNS: central nervous system; GHRP-6: growth hormone-releasing peptide 6; GHSR-1a: growth hormone secretagogue receptor type 1a; MK-0677: ibutamoren mesylate; pCREB: phosphorylated adenosine 3'5' cyclic monophosphate-response element binding protein. Here, APP is linked to Alzheimer disease.