Spatio-Temporal Correlates of Gene Expression and Cortical Morphology across Life Course and Aging

Evidence from independent neuroimaging and genetic studies supports the concept that brain aging mirrors development. However, it is unclear whether mechanisms linking brain development and aging provide new insights to delay aging and potentially reverse it. This study determined biological mechanisms and phenotypic traits underpinning brain alterations across the life course and in aging by examining spatio-temporal correlations between gene expression and cortical volumes (n=3391) derived from the life course dataset (3-82 years) and the aging dataset (55-82 years). We revealed that a large proportion of genes whose expression was associated with cortical volume across the life course were in astrocytes. These genes, which showed up-regulation during development and down-regulation during aging, contributed to fundamental homeostatic functions of astrocytes crucial, in turn, for neuronal functions. Included among these genes were those encoding components of cAMP and Ras signal pathways, as well as retrograde endocannabinoid signaling. Genes associated with cortical volumes in the aging dataset were also enriched for the sphingolipid signaling pathway, renin-angiotensin system (RAS), proteasome, and TGF-beta signaling pathway, which is linked to the senescence-associated secretory phenotype. Neuroticism, drinking, and smoking were the common phenotypic traits in the life course and aging, while memory was the unique phenotype associated with aging. These findings provide biological mechanisms and phenotypic traits mirroring development and aging as well as unique to aging.