What causes depression?

Clinicians and researchers say depression arises from a combination of genetic, biological, psychological and social factors, making it a complex medical condition rather than a simple mood fluctuation. Scientific consensus points to inherited vulnerability: people with a family history of mood disorders carry higher risk, and twin studies indicate substantial heritability.

Biological contributors include altered neurotransmitter systems, disrupted neural circuits involved in mood regulation, endocrine imbalances such as dysregulated cortisol, and evidence of low-grade inflammation. Brain-imaging studies link structural and functional differences in the prefrontal cortex and limbic system to depressive symptoms, experts report.

Psychological factors such as negative thinking patterns, maladaptive coping strategies, and early-life adversity — including physical or emotional abuse — increase susceptibility. Clinicians stress that a single traumatic event can trigger depression in some individuals, while chronic stress and social isolation exert a cumulative effect over time.

Medical illnesses and medications also play a role. Chronic pain, thyroid disease, neurological disorders and certain prescriptions can precipitate depressive episodes, clinicians warn. Substance use both mimics and exacerbates depression, complicating diagnosis and treatment.

Socioeconomic determinants are significant: poverty, unemployment, unstable housing, and discrimination are associated with higher rates of depression. Public-health experts emphasize that community-level interventions and access to care reduce long-term burden.

Diagnosis typically requires a clinical assessment guided by accepted criteria and screening tools, after which treatment may include psychotherapy, medication, lifestyle interventions and social supports. Emerging research investigates immune modulation, personalized medicine based on genetic profiles, and neuromodulation techniques.

Experts urge that depression is treatable and encourage early help-seeking. Reliable information and coordinated care can improve outcomes and reduce stigma, clinicians conclude. Policy makers and health systems are urged to expand mental-health workforces, integrate behavioral health into primary care, fund school-based prevention programs, and support workplace accommodations to address rising community needs and reduce disparities.