Longitudinal serum S100β and brain ageing in the Lothian Birth Cohort 1936

Elevated serum and cerebrospinal fluid concentrations of S100β, a protein predominantly found in glia, are associated with intracranial injury and neurodegeneration, though concentrations are also influenced by several other factors. The longitudinal association between serum S100β concentrations and brain health in non-pathological ageing is unknown. In a large group (baseline N = 593; longitudinal N = 414) of community-dwelling older adults at ages 73 and 76 years, we examined cross-sectional and parallel longitudinal changes between serum S100β and brain MRI parameters: white matter hyperintensities (WMH), perivascular space visibility, white matter fractional anisotropy (FA) and mean diffusivity (MD), global atrophy and grey matter volume. Using bivariate change score structural equation models, correcting for age, sex, diabetes and hypertension, higher S100β was cross-sectionally associated with poorer general FA (r = -0.150, p = 0.001), which was strongest in the anterior thalamic (r = -0.155, p < 0.001) and cingulum bundles (r = -0.111, p = 0.005), and survived false discovery rate (FDR) correction. Longitudinally, there were no significant associations between changes in brain imaging parameters and S100β following FDR correction. These data provide some weak evidence that S100β may be an informative biomarker of brain white matter ageing.