ODC1 and Alzheimer disease: Alterations in the concentrations of N-acetylisoputreanine-gamma-lactam, a catabolic product of spermidine that is formed from N-actetylspermidine73 support a potentially altered metabolism of polyamines in AD: the stimulation of ornithine decarboxylase in the AD process leads to increased levels of N-acetylspermidine and spermidine74.