Potential mechanisms by which exercise could improve cognitive function include increases in cerebral blood flow, increased neurotrophic factors (BDNF, insulinlike growth factor-1 [IGF-1]), downregulation of neurotoxic factors (insulin, C-reactive protein, cortisol, interleukin-6 [IL-6]), and other inflammatory cytokines, prevention or better control of chronic diseases (e.g., hypertension, stroke, diabetes, cardiovascular disease) and prevention of depression (241). The gene discussed is IL6; the disease is major depressive disorder.