Schizophrenia is a psychiatric disorder characterized by a distorted perception of reality and bizarre behavior. While the exact cause of schizophrenia is not known, multiple biological, psychological and social factors are thought to play parts in the development of the disease.
The incidence of schizophrenia in the western world is estimated at ~15:100,000 population. The lifetime prevalence of schizophrenia is ~7:1,000. Males have a 1.5 times higher risk of developing schizophrenia compared to females. Patients with schizophrenia have a mortality ratio of 2.6 against patients without schizophrenia. Most of these deaths are attributable to suicide and presence of co-morbid physical health conditions 1.
The diagnostic criteria for schizophrenia according to the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) 6 is identified as the presence of two out of five (for at least six months) of the following:
- auditory hallucinations
- catatonic symptoms
- negative symptoms (e.g. reduced emotional expression)
- disorganized speech
In addition, these symptoms must not be attributable to substance use or a physical health condition.
The following health conditions have been identified as potential organic causes of schizophrenia:
- traumatic brain injury
- cerebral lupus
- subdural hematoma
- brain tumor
- metachromatic leukodystrophy
- Wilson disease
- HIV infection
- vitamin B12 deficiency
- vitamin D deficiency
- multiple sclerosis
- dementia of any etiology
- temporal lobe epilepsy 2
Most patients with a first episode of psychosis will receive a CT brain to rule out organic causes of schizophrenia.
CT and MRI
The majority of the findings seen with CT scan can also be observed with an MRI. Ventricular enlargement with cortical atrophy (particularly in the frontal lobes) is seen in patients with chronic schizophrenia. Ventricular size has been reported to increase with progression of the disease 3.
Further research has found that temporal lobe volumes in patients with schizophrenia are smaller compared to control patients. This includes a reduction in the size of the amygdala-hippocampus complex, which is responsible for memory formation and emotional reactions (both of which are blunted in schizophrenia).
The superior temporal gyrus (which is part of Wernicke's area) is also reduced in volume, which could possibly explain the catatonic behavior and problems with language seen in certain patients with schizophrenia.
Some studies have also identified parietal lobe (particularly the cingulate and supramarginal gyri) and occipital lobe atrophy, although these are not common and are often present in later stages of the disease.
On initial screening, a reduction in the size of the caudate is observed. With neuroleptic medication exposure, the size of basal ganglia structures appears to increase. The size of the thalamus also appears to be reduced, although it is difficult to ascertain this on both CT and MRI. The corpus callosum is also thicker in patients with schizophrenia.
Majority of these findings can be observed in patients presenting with a first episode of psychosis 4,5.
It is also important to rule out other organic causes of psychosis as mentioned above.
Treatment and prognosis
The treatment of schizophrenia is aimed at alleviation of symptoms (if appropriate), in particular addressing the negative symptoms, and providing psychosocial support. Acute psychotic patients will often need to be admitted to an inpatient facility, usually only temporarily, for their own and others' safety.
If an organic cause for psychosis is identified, it must be treated accordingly.
- neuroimaging in schizophrenia, although not diagnostic, can provide several hints for the diagnosis
- organic causes of a first episode of psychosis must be ruled out to confirm a diagnosis of schizophrenia
- 1. McGrath J, Saha S, Chant D, Welham J. Schizophrenia: a concise overview of incidence, prevalence, and mortality. (2008) Epidemiologic reviews. 30: 67-76. doi:10.1093/epirev/mxn001 - Pubmed
- 2. Keshavan MS, Kaneko Y. Secondary psychoses: an update. (2013) World Psychiatry. 12 (1): 4. doi:10.1002/wps.20001 - Pubmed
- 3. B P Illowsky, D M Juliano, L B Bigelow, D R Weinberger. Stability of CT scan findings in schizophrenia: results of an 8 year follow-up study. (1988) J Neurol Neurosurg Psychiatry. 55 (12). Pubmed
- 4. Shenton ME, Dickey CC, Frumin M, McCarley RW. A review of MRI findings in schizophrenia. (2001) Schizophr Res 49(1-2): 1–52. Pubmed
- 5. Shenton ME, Kikinis R, Jolesz FA, Pollak SD, LeMay M, Wible CG, Hokama H, Martin J, Metcalf D, Coleman M. Abnormalities of the left temporal lobe and thought disorder in schizophrenia. A quantitative magnetic resonance imaging study. (1992) The New England journal of medicine. 327 (9): 604-12. doi:10.1056/NEJM199208273270905 - Pubmed
- 6. American Psychiatric Association. (2013). Diagnostic and statistical manual of mental disorders (5th ed.). Arlington, VA: Author.