It's a mouse study, but possibly has implications for testosterone levels and dementia in older men.
A dysfunction in the blood-brain barrier (BBB) is associated with many neurological and metabolic disorders. We investigated the effects of gonadal testosterone depletion on the integrity of capillary BBB and the surrounding parenchyma in male mice. Our results show increased BBB permeability for different tracers and endogenous immunoglobulins in chronically testosterone-depleted male mice. These results were associated with disorganization of tight junction structures shown by electron tomography and a lower amount of tight junction proteins. BBB leakage was also accompanied by activation of astrocytes and microglia, and up-regulation of inflammatory molecules. Supplementation of castrated male mice with testosterone restored BBB selective permeability, tight junction integrity, and almost completely abrogated the inflammatory features.