Association between irisin and cognition in a cohort of dementia patients

Abstract

Objective: Dementia is a common disabling neurocognitive disorder associated with a progressive deterioration of brain functions. There is an increasingly emerging need to identify specific markers of dementia. The myokine irisin, a novel positive mediator of exercise in the brain, shows neuroprotective functions against Alzheimer's disease (AD). Here, we investigated the association of irisin with cognition in a cohort of dementia patients.

Methods: Cerebrospinal fluid (CSF) and serum irisin levels were evaluated using enzyme-linked immunoassays in patients with AD (n=82), mild cognitive impairment (MCI, n=44), and subjective memory complaint (SMC, n=20). An extensive neuropsychological examination was performed using 18 tests including the Mini Mental State Examination (MMSE), and Frontal Assessment Battery (FAB), two screening tests used to assess global cognitive status. Psychometric tests such as Trail Making Test (version A and B), Rey–Osterrieth Complex Figure, Stroop Color and Word Test, Verbal Fluency test, Digit Span, etc., were administered to evaluate the efficiency of single domain (memory, attention, executive functions, language, and visuospatial abilities).

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 serum and global cognitive efficiency, as well as with specific cognitive domains such as memory, executive functions, attention, visuospatial abilities, and language. Higher levels of CSF and serum irisin were associated with better cognitive performance.

Interpretation: Our results highlight the key involvement of irisin in cognition, indicating its potential role as a cognitive biomarker of AD progression.