Chapter 15: Psychological Disorders

Psychological disorders are characterized by significant disturbances in cognition, emotion, and behavior that reflect underlying biological, psychological, or developmental dysfunction and result in measurable distress or impairment in functioning. The chapter emphasizes that diagnosis requires standardization through the Diagnostic and Statistical Manual of Mental Disorders (DSM-5), the primary classification system used in clinical practice and research within the United States, and the International Classification of Diseases (ICD), which provides a global framework for mental health assessment. Understanding the origins of psychological disorders requires familiarity with multiple theoretical perspectives, including the biological perspective that attributes disorders to genetic predispositions, neurochemical imbalances, and structural brain abnormalities, the psychosocial perspective that highlights learning mechanisms and cognitive patterns, and the diathesis-stress model, which integrates these approaches by proposing that disorders emerge from the interaction between individual vulnerability factors and environmental stressors. The chapter systematically surveys major diagnostic categories, including anxiety-related conditions such as specific phobias, social anxiety disorder, panic disorder, generalized anxiety disorder, obsessive-compulsive disorder, and posttraumatic stress disorder, which collectively represent the most prevalent mental health conditions. Mood disorders, including major depressive disorder and bipolar disorder, involve substantial alterations in emotional regulation and functioning. Schizophrenia represents a severe psychotic condition characterized by hallucinations, delusions, and disorganized cognition. The chapter also addresses dissociative disorders, which involve disruptions in identity and memory, and personality disorders, which manifest as entrenched behavioral and interpersonal patterns organized into distinct clinical clusters. Finally, the chapter examines neurodevelopmental disorders with childhood onset, particularly attention-deficit/hyperactivity disorder and autism spectrum disorder, emphasizing evidence-based understanding of their neurobiological foundations and rejecting unsupported etiological claims.