Correlation Between Irisin and Cognitive Functions in Alzheimer Dementia

Objective: The myokine irisin, a recent positive mediator of exercise in the brain, shows neuroprotective functions against Alzheimer's disease (AD). The association between irisin and cognition has never been explored in a biologically defined cohort of patients. Thus, in the present study, we investigated the association of irisin with multidomain cognition in patients showing dementia-related symptomatology. Methods: Cerebrospinal fluid (CSF) and serum irisin levels were evaluated using enzyme-linked immunoassays in a cohort of subjects with a confirmed biomarker evidence of AD, including AD (n = 82), mild cognitive impairment (MCI, n = 44), and subjective memory complaint (SMC, n = 20) patients. The results of this analysis were correlated with global cognitive efficiency assessed by Mini-Mental State Examination, and multidomain cognition evaluated by a battery of psychometric tests. Results: Decreased CSF and serum irisin levels were observed in AD and MCI patients compared to SMC. A significant correlation has been found between irisin in the CSF and global cognitive efficiency, as well as with specific cognitive domains such as memory, executive functions, attention, visuospatial abilities, and language. For serum irisin, the correlation analysis evidenced similar results to those observed for the CSF. Interpretation: Our results highlight the key involvement of irisin in multidomain cognition, indicating its potential role as a cognitive biomarker of AD progression.