A Mixed-Effects Model of Associations between Interleukin-6 and Hippocampal Volume.

Previous studies report hippocampal volume loss can help predict conversion from normative aging to mild cognitive impairment (MCI) to dementia. Additionally, a growing literature indicates that stress-related allostatic load may increase disease vulnerability. The current study examined the relationship between stress related cytokines (i.e., interleukin-6 - IL-6), cognition as measured by Mini Mental Status scores (MMSE), and hippocampal volume. Mixed-models were employed to examine both within (across time) and between subjects effects of IL-6 and hippocampal volume on MMSE score among 566 participants from the Alzheimer's Disease Neuroimaging Initiative (ADNI). The within subjects analysis found left hippocampal volume significantly (p= .009) predicted MMSE score. Between subjects analysis found the effect of IL-6 on MMSE was moderated by right hippocampal volume (p = .001). These results replicate previous findings and also extend prior work demonstrating stress-related cytokines may play a role in Alzheimer's disease (AD) progression.