Saiki S, et al. - Since spermidine and spermine experimentally improve longevity through autophagy induction under physiological conditions, researchers assessed the ability of each polyamine metabolite to be an age-related, diagnostic, and severity-related biomarker for Parkinson's disease (PD). According to results, spermine was the strongest autophagy inducer among polyamine metabolites, particularly in SH-SY5Y cells. Compared to controls, no significant genetic differences have been identified in five genes encoding enzymes linked to spermine/spermidine metabolism. Overall, the authors concluded that spermine synthesis and N1,N8-diacetylspermidine can be helpful biomarkers related to diagnosis and severity for PD.