Associations of systemic inflammation with frontotemporal functional network connectivity and out-degree social-network size in community- dwelling older adults

Abstract

Increasing evidence suggests thatsystemicinflammationadversely affects social experiences and behaviors ofolderadultsby changing thefunctionalstate of the brain. In this study, we investigated the relationships amongsystemicinflammation,functionalnetworkconnectivity(FNC) of the whole brain, andsocial-networksizeusing completesocial-networkdata ofolderadultsresiding in a Korean village. Sixty-one participants were recruited from the Korean Social Life, Health, and Aging Project (KSHAP). Participants underwent a resting-statefunctionalmagnetic resonance imaging scan. High sensitivity C-reactive protein (hs-CRP) levels were measured as aninflammationmarker. In-degree andout-degreenetworksizes were calculated based on the total number of intimate social relationships per participant. We demonstrated that hs-CRP levels were associated with decreasedfrontotemporalFNC. StrongerfrontotemporalFNC was significantly correlated with a largerout-degreenetworksize, suggesting that impairedfrontotemporalcommunication inolderadultsdecreases perceived social connectedness with other people. An exploratory mediation analysis supported the observation that increasedsystemicinflammationcontributes to reducedout-degreesocial-networksizeamongolderadultsby changingfrontotemporalFNC. The present findings provide meaningful insight into the complex relationship betweensystemicinflammationand social quality of life.