The period saw psychiatry shift toward a biological framework, foregrounding endocrine dynamics and neurochemical regulation as central drivers of mood and psychotic disorders. Endocrine stress responses and metabolic pathways were linked to disease trajectories, connecting physiology to clinical phenomena and contributing to the growth of psychosomatic medicine. The introduction of mood-stabilizing medications and the clarifying of endogenous psychosis concepts broadened diagnostic and treatment horizons, integrating biological mechanisms with phenomenology.