TPH2 and depressive disorder: In animal models without viral infection, EFV primarily causes neuropsychiatric issues, neuroinflammation, developmental delays, and metabolic changes, often linked to its effects on the central nervous system (CNS) and cholesterol metabolism, impairments in short-term memory and spatial learning, anxiety and depression-like behaviours, dysregulation of the Tph2 gene, and alterations in serotonin (5-HT) levels in certain brain structures such as the amygdala [9,12,15,22].