From a neurobiological perspective, regular PA enhances the regulation of the hypothalamic–pituitary–adrenal (HPA) axis, reduces cortisol secretion, and increases levels of serotonin, dopamine, and brain-derived neurotrophic factor (BDNF), all of which are linked to improved mood regulation and reduced anxiety symptoms (Dishman et al., 1985; Yarar & Telci, 2020). The gene discussed is BDNF; the disease is Anxiety.