Expression patterns of risk genes associated with three evolutionarily relevant syndromes in rhesus macaque and human brains.

Depressive disorder (DD), Alzheimer's disease (AD), and schizophrenia (SZ) are evolutionarily relevant traits that disrupt neural networks supporting affect and cognition. While genome-wide association studies have identified risk-related genes for these diseases, how the expression of these genes compare across species remains unclear. In this study, we examined the spatial and temporal expression of ~2000 disease-associated genes in human and rhesus macaque brains. Distinct cross-species signatures emerged. DD-linked genes showed broad cortical-subcortical expression in humans but were confined to subcortical regions in macaques. The divergent subset was enriched for neuron differentiation, migration, synaptic signalling, and cognition. SZ-linked genes were expressed across cortical-subcortical-cerebellar structures in humans. AD-linked genes showed postnatal cortical-hippocampal macaque expression, and broader cortical-subcortical human expression. Cross-species spatial comparisons revealed a significant negative correlation for DD genes, suggesting a broader spatial distribution of DD-related gene expression in humans, extending to distributed emotion-cognition networks, compared to affective hubs in macaques. SZ genes exhibited a similar, though non-significant, negative trend, while AD genes showed a weak, non-significant correlation, indicating an absence of systematic expression shifts. Together, evolutionary shifts in gene expression may have shaped emotional and cognitive functions in humans, and susceptibility to psychiatric and neurodegenerative disorders.