Elevated spermidine serum levels in mild cognitive impairment, a potential biomarker of progression to Alzheimer dementia, a pilot study

•We compared serum levels of the polyamine spermidine between MCI, AD and control subjects.•Serum levels of MCI was significantly higher in MCI subjects.•Spermidine serum levels correlated with AD disease severity (MMSE, CDR and CDR-SOB).•Role of Spemidine and polyamines in AD pathophysiology warrants further investigations.