Chapter 12: Schizophrenia Spectrum and Other Psychotic Disorders

Schizophrenia is characterized by disturbances across multiple domains including cognition, perception, emotion, and motor behavior, resulting in significant functional impairment. The symptom profile is organized into three primary categories: positive symptoms involving distortions or excesses of normal functioning such as delusions and hallucinations; negative symptoms reflecting deficits or absence of normal behavior including avolition, alogia, anhedonia, and blunted affect; and disorganized symptoms encompassing disorganized speech, inappropriate affect, and catatonic features. The chapter also addresses related diagnostic entities including schizophreniform disorder, which presents with short-term symptomatology lasting one to six months; schizoaffective disorder, combining psychotic features with mood disturbances; delusional disorder, characterized by persistent false beliefs without additional psychotic symptoms; brief psychotic disorder triggered by acute stress; and substance-induced psychotic disorder. Understanding etiology requires consideration of multiple biological and environmental pathways. Genetic vulnerability represents a significant risk factor, with substantially elevated incidence among first-degree relatives. Neurobiological mechanisms include dysregulation of dopamine neurotransmission, particularly in mesolimbic and mesocortical pathways, and dysfunction of glutamatergic systems involving NMDA receptor hypofunction. Structural brain abnormalities such as ventricular enlargement and reduced gray matter volume contribute to the pathophysiology. Prenatal and perinatal complications alongside environmental stressors, including urbanicity, social isolation, and family expressed emotion, interact with biological vulnerability to precipitate illness onset. Treatment integrates pharmacological and psychosocial approaches. First-generation antipsychotics effectively target positive symptoms but carry significant risks for extrapyramidal side effects and tardive dyskinesia. Second-generation antipsychotics offer improved tolerability regarding motor symptoms, though metabolic complications present clinical challenges. Long-acting injectables enhance medication adherence in non-compliant populations. Psychosocial interventions including cognitive-behavioral therapy addressing delusional thinking, social skills training, family therapy focused on reducing expressed emotion, assertive community treatment, and supported employment programs promote recovery and community integration while reducing relapse rates.