European Journal of Biomedical and Pharmaceutical Sciences

DEPRESSION: ETIOLOGY, PATHOPHYSIOLOGY, CLINICAL ASSESSMENT AND THERAPEUTIC APPROACHES IN VIEW OF RECENT STUDIES UPDATED REVIEW

*G. Lakshmana, Dr. J. N. Suresh Kumar, D. Saikiran, B. Narendra Refdy, G. Sunitha, S. Venkatesh

ABSTRACT

Depression is a common and disabling psychiatric disorder characterized by persistent low mood, loss of interest or pleasure, cognitive and emotional disturbances, and a range of somatic symptoms. Major depressive disorder (MDD) is a heterogeneous condition arising from complex interactions among genetic vulnerability, environmental stress, psychological factors, neurobiological abnormalities and social determinants. Contemporary research has moved beyond a simple monoamine-deficiency model toward an integrated understanding involving altered neural circuits, impaired neuroplasticity, hypothalamic-pituitary-adrenal-axis dysfunction, inflammation, immune signaling, metabolic abnormalities and the microbiota-gut-brain axis. Diagnosis remains primarily clinical, although standardized instruments such as the Patient Health Questionnaire-9 can support screening. Treatment includes pharmacotherapy, psychotherapy, exercise and other psychosocial interventions. Selective serotonin reuptake inhibitors, serotonin-norepinephrine reuptake inhibitors and other antidepressants remain important pharmacological options. Cognitive behavioral therapy is an established psychological intervention, while digital psychological interventions and exercise have increasing evidence. Treatment-resistant depression remains a major challenge and has stimulated development of rapid-acting and mechanistically novel interventions, particularly ketamine and esketamine, together with neuromodulation approaches. Emerging research is investigating neuroplasticity, inflammatory mechanisms, metabolic pathways and gut-brain interactions as potential therapeutic targets. An integrated, individualized and biopsychosocial approach is therefore central to contemporary depression research and management.

Keywords: Depression, major depressive disorder, antidepressants, psychotherapy, neuroplasticity and inflammation, gut-brain axis treatment-resistant depression, ketamine, and esketamine.