Scientific programme

The recently discovered hormone, irisin, is proposed to improve brain health (due to induction of brain-derived neurotrophic factor). The aim of the current study was to evaluate the cross-sectional relationship between serum irisin levels and cognitive function in a cohort of cognitively healthy older adults.

This study includes data from 201 cognitively healthy older adults from the Australian Imaging, Biomarkers and Lifestyle (AIBL) Study of Ageing. Serum irisin levels were quantified using the third generation of a commercially available ELISA kit (Phoenix Pharmaceuticals, Burlingame, USA). Cognitive function was assessed using a comprehensive neuropsychological battery, with individual test scores used to compute composite scores for attention, executive function, episodic memory, and to generate a Preclinical Alzheimer’s Cognitive Score. Analyses of covariance, adjusting for age, gender and apolipoprotein E (APOE) ε4 allele carriage, were used to evaluate the relationship between irisin and the cognitive composite scores. Analyses were then rerun following stratification of the cohort by APOE ɛ4 carrier status.

Irisin was not a significant predictor of any of the composite scores; however, the association between irisin and attention was trend level (F = 3.76, p = 0.054). Following stratification of the cohort by APOE ɛ4 carrier status, higher levels of irisin were associated with better performance on attention tasks among the ɛ4 non-carriers (F = 5.73, p = 0.018).

Our cross-sectional results suggest an APOE genotype-contingent relationship between irisin and cognition. This association warrants further investigation in larger cohorts, and utilising longitudinal study design.