Clinical meaning
Advanced psychiatric-mental health practice requires integration of neurobiological, psychological, and social models of mental illness to guide comprehensive assessment and evidence-based treatment. The monoamine hypothesis of depression — reduced serotonergic and noradrenergic neurotransmission — remains foundational but is now understood as oversimplified; current models emphasize neuroplasticity deficits, hypothalamic-pituitary-adrenal (HPA) axis dysregulation with chronic cortisol elevation, neuroinflammation with elevated pro-inflammatory cytokines, and gut-brain axis dysfunction. Antipsychotic pharmacology targets dopamine D2 receptor blockade in the mesolimbic pathway (reducing positive symptoms) but also affects the nigrostriatal pathway (causing extrapyramidal symptoms), tuberoinfundibular pathway (causing hyperprolactinemia), and mesocortical pathway (potentially worsening negative symptoms) — second-generation antipsychotics additionally block serotonin 5-HT2A receptors, reducing EPS risk but increasing metabolic side effects. The clinician must monitor for metabolic syndrome (weight, fasting glucose, lipid panel), QTc prolongation, and neuroleptic malignant syndrome when prescribing antipsychotics.