Schizophrenia

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Basics

Schizophrenia is a severe and persistent mental illness characterized by delusions, hallucinations, disorganization of thought and behavior, cognitive dysfunction, and impairment in reality testing.

Description

  • Major psychiatric disorder with a variable course, typically involving prodromal, active, and residual psychotic symptoms with disturbances in thought, speech, affect, behavior, and perception
  • DSM-5 eliminated subcategories of schizophrenia (paranoid, disorganized, catatonic, etc.).
  • System(s) affected: central nervous system (CNS)

Epidemiology

Incidence
  • 7.7 to 43/100,000
  • Predominant sex: male-to-female ratio = 1.4:1.0
  • Age of onset: typically <30 years, earlier in males (late teens to mid-20s) than females (early 20s to early 30s), with a smaller peak that occurs in women >45 years; more subtle changes in cognition and functioning can precede the diagnosis (prodromal period) by several years.

Prevalence
  • Lifetime (1%): highest prevalence in lower socioeconomic classes and urban settings (2-fold higher risk)
  • 1.1% of the population >18 years old; similar rates in all countries

Etiology and Pathophysiology

  • Stems from a complex interaction between genetic and environmental factors; higher incidence if prenatal infection or hypoxia, winter births, first-generation immigrants, advanced paternal age, drug use, and genetic (velocardiofacial) syndromes
  • Overstimulation of mesolimbic dopamine D2 receptors, deficient prefrontal dopamine, and aberrant prefrontal glutamate (NMDA) activity results in perceptual disturbances, disordered thought process, and cognitive impairments.

Genetics
If first-degree biologic relative has schizophrenia, risk is 8–10% (a 10-fold increase).

General Prevention

  • Currently, no known preventive measures decrease the incidence of schizophrenia. Early intervention programs, however, aim to identify people at high risk and limit the duration of untreated psychosis.
  • It is important to educate all patients on the risks around marijuana use, especially those in a potential prodromal period or those with a family history of psychosis.
  • Interventions to improve long-term outcome and associated comorbid conditions are employed during management.

Commonly Associated Conditions

  • Nicotine dependence (>50%) and substance use disorders are common and lead to significant long-term medical and social complications.
  • Metabolic syndrome, diabetes mellitus, obesity, and certain infectious diseases, including HIV, hepatitis B, and hepatitis C all occur in higher-than-expected rates in individuals with schizophrenia.

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Basics

Schizophrenia is a severe and persistent mental illness characterized by delusions, hallucinations, disorganization of thought and behavior, cognitive dysfunction, and impairment in reality testing.

Description

  • Major psychiatric disorder with a variable course, typically involving prodromal, active, and residual psychotic symptoms with disturbances in thought, speech, affect, behavior, and perception
  • DSM-5 eliminated subcategories of schizophrenia (paranoid, disorganized, catatonic, etc.).
  • System(s) affected: central nervous system (CNS)

Epidemiology

Incidence
  • 7.7 to 43/100,000
  • Predominant sex: male-to-female ratio = 1.4:1.0
  • Age of onset: typically <30 years, earlier in males (late teens to mid-20s) than females (early 20s to early 30s), with a smaller peak that occurs in women >45 years; more subtle changes in cognition and functioning can precede the diagnosis (prodromal period) by several years.

Prevalence
  • Lifetime (1%): highest prevalence in lower socioeconomic classes and urban settings (2-fold higher risk)
  • 1.1% of the population >18 years old; similar rates in all countries

Etiology and Pathophysiology

  • Stems from a complex interaction between genetic and environmental factors; higher incidence if prenatal infection or hypoxia, winter births, first-generation immigrants, advanced paternal age, drug use, and genetic (velocardiofacial) syndromes
  • Overstimulation of mesolimbic dopamine D2 receptors, deficient prefrontal dopamine, and aberrant prefrontal glutamate (NMDA) activity results in perceptual disturbances, disordered thought process, and cognitive impairments.

Genetics
If first-degree biologic relative has schizophrenia, risk is 8–10% (a 10-fold increase).

General Prevention

  • Currently, no known preventive measures decrease the incidence of schizophrenia. Early intervention programs, however, aim to identify people at high risk and limit the duration of untreated psychosis.
  • It is important to educate all patients on the risks around marijuana use, especially those in a potential prodromal period or those with a family history of psychosis.
  • Interventions to improve long-term outcome and associated comorbid conditions are employed during management.

Commonly Associated Conditions

  • Nicotine dependence (>50%) and substance use disorders are common and lead to significant long-term medical and social complications.
  • Metabolic syndrome, diabetes mellitus, obesity, and certain infectious diseases, including HIV, hepatitis B, and hepatitis C all occur in higher-than-expected rates in individuals with schizophrenia.

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