About Schizophrenia

Schizophrenia is a spectrum of serious neuro-psychiatric brain diseases in which people interpret reality abnormally. Schizophrenia may result in some combination of hallucinations, delusions, and extremely disordered thinking and behavior that impairs daily life.


People with schizophrenia typically require lifelong treatment. Early treatment may help improve long-term prognosis and get symptoms under control before serious complications develop.


Precise prevalence estimates of schizophrenia are difficult to obtain due to clinical and methodological factors such as the complexity of schizophrenia diagnosis, its overlap with other disorders, and varying methods for determining diagnoses.5

The National Institute of Mental Health (NIMH) estimates the prevalence of schizophrenia and related psychotic disorders in the United States ranges between 0.25% and 0.64%. Internationally, this estimate is 0.33% to 0.75%.

However, we believe these figures dramatically underreport the prevalence of schizophrenia and there are differing views about the size of the schizophrenia patient population in the United States. Surveillance efforts to produce reliable estimates are infrequent. Moreover, persons with this condition often reside in locations that are hard for surveyors to access including homeless shelters, county jails, state prisons and nursing facilities.

  • Across studies that use household-based survey samples, clinical diagnostic interviews, and medical records at least 1 in 200 people in the US are estimated to have schizophrenia and related psychotic disorders.2,5
  • Studies that include additional populations, such as institutionalized individuals, suggest schizophrenia and related psychotic disorders may affect more than 1 in 100 people.5,1,2
  • International prevalence estimates among non-institutionalized individuals fall within this same range.5


It is estimated approximately 50% of patients with schizophrenia do not take their prescribed medications as directed. The most common reason is anosognosia, meaning they are unaware of their condition.

Lack of treatment leads to severe negative health outcomes, including a life expectancy shortened by an average of 28.5 years. 

Approximately half of individuals with schizophrenia have co-occurring mental or behavioral health disorders.

Co-occurring medical conditions such as heart disease, liver disease, and diabetes contribute to the higher premature mortality rate among individuals with schizophrenia.

Following illness onset, 25-50% of those living with schizophrenia attempt suicide.

At least 50% of people with severe psychiatric illnesses like schizophrenia smoke, compared to 23% of the general population. 

Smoking-related illnesses cause half of all deaths among people with psychiatric disorders. 


Those diagnosed with schizophrenia smoke more than half of all cigarettes produced in the United States, and they are only half as likely as other smokers to quit.

Genetic Causes

According to MedlinePlus, variations in many genes may contribute to the risk of developing schizophrenia.


Deletions or duplications of genetic material are thought to increase schizophrenia risk. In particular, a small deletion (microdeletion) in a region of chromosome 22 called 22q11 may be involved in a small percentage of cases of schizophrenia. Some individuals with this deletion have other disorders such as heart abnormalities, immune system problems, and cleft palate.


Genetic changes can also interact with environmental factors associated with increased risk of developing schizophrenia, such as exposure to infections before birth or severe stress during childhood. 

The direct impact of genetic changes are not well understood, so this is an active area of research. 

A Biological Basis for Schizophrenia

Many genetic, post-mortem, and neuroimaging studies have demonstrated clear evidence of schizophrenia’s biological underpinnings. Perhaps one of the more simple, compelling facts is heritability and twin concordance: If one twin in an identical twin pair has schizophrenia, the other will have a 50% chance of also developing the illness, even if the second child was raised in a different environment. This number is comparable to that for Alzheimer’s disease and greater than that for Parkinson’s disease.


A comparison of schizophrenia to Alzheimer’s and Parkinson’s—two disorders that unambiguously have a neurological basis—quickly makes a compelling case for schizophrenia as a neurological disorder.


All three share multiple features including significant brain and cognitive deterioration. The diagnostic approach, treatment types, and genetic basis clearly speak to the consideration of schizophrenia as a neurological disorder. 

Where these disorders depart is the personal and social impact for diagnosed individuals. With a diagnosis of Alzheimer’s or Parkinson’s, timely and appropriate care is available. With schizophrenia, similar access is far from guaranteed, with striking rates of patients being untreated, homeless, or incarcerated. 


While schizophrenia appears to legitimately deserve consideration as a neurological disorder based on clinical and scientific grounds, the lack of reclassification has sadly been associated with much suffering, debilitation, and public health cost. 


  1. Kessler RC et al. The prevalence and correlates of nonaffective psychosis in the National Comorbidity Survey Replication (NCS-R). Biol Psychiatry. 2005;58(8):668-676.
  2. Wu EQ. Annual prevalence of diagnosed schizophrenia in the USA: a claims data analysis approach. Psychol Med. 2006 Nov;36(11):1535-40.
  3. Desai, PR et. al. Estimating the direct and indirect costs for community-dwelling patients with schizophrenia. Journal of Pharmaceutical Health Services Research, 2013 Jul; 4(4):187-194.
  4. Saha S, Chant D, Welham J, McGrath J. A systematic review of the prevalence of schizophrenia. PLoS Med. 2005 May;2(5):e141. PMID: 15916472
  5. Moreno-Kustner B et. al. Prevalence of psychotic disorders and its association with methodological issues. A systematic review and meta-analyses. PLoS One. 2018;13(4):e0195687.
  6. Bourdon KH et. al. Estimating the prevalence of mental disorders in U.S. adults from the Epidemiologic Catchment Area Survey. Public Health Rep. 1992;107(6):663-668.
  7. Regier DA et. al. The de facto US mental and addictive disorders service system. Epidemiologic catchment area prospective 1-year prevalence rates of disorders and services. Arch Gen Psychiatry. 1993 Feb;50(2):85-94