According to the National Institutes of Health, approximately 1 percent of Americans suffer from schizophrenia, a chronic brain disorder characterized by distorted cognitive functions, hallucinations and disorganized speech. Schizophrenia has been linked to many abnormalities in brain structure, function, and biochemistry.
Loss of Brain Gray Matter
Gray matter consists of different parts of neurons, such as cell bodies, dendrites and axons. Sometimes, a myelin sheet forms on top of gray matter. Most gray matter does not have this white cover. Interestingly, schizophrenics have been found to have a reduced volume of gray matter in the brain, especially in the temporal and frontal lobes. The University of California’s School of Medicine reported in a study published in volume 98 of Proceedings of the National Academy of Sciences in 2001 that early-onset schizophrenics had severe gray matter loss already as adolescence. Early-onset patients were scanned with MRIs at two-year intervals at three time points. Loss of gray matter was found first in the parietal lobe, then in temporal lobes. Interestingly, this damage correlated with the severity of psychotic symptoms.
Enlarged Ventricles
Ventricles are cavities within the brain. Usually, an enlarged ventricle is a sign that the brain has shrunk, or that extra fluid has built up in the ventricles. Many schizophrenics have been found to have enlarged ventricles that seem to be due to the shrinking of the brain. For example, the University of Naples’ department of psychiatry in Italy reported in the March issue of Schizophrenia Bulletin in 2008 that by employing MRI, researchers had discovered that lateral ventricles were larger in patients with schizophrenia than in healthy controls. Schizophrenics also had smaller prefrontal cortexes and temporal lobes than healthy subjects.
The Amygdala and the Hippocampus
The amygdala is an area in the brain that processes emotions. The hippocampus is related to long-term memory. Scientists have also turned to these areas to find out whether they might be different in patients with schizophrenia. The results received by researchers are inconsistent. Some studies have reported that these areas are smaller, while others have found these parts to have no differences. For example, a study published in volume 180 of the British Journal of Psychiatry in 2002 found no differences in the size of the amygdala between normal controls and 18 schizophrenic patients.
Neurotransmitters
Dopamine is a neurotransmitter that is associated with reinforcement. Dr. J. Van Rossum suggested in 1967 that schizophrenia is caused by excess amounts of dopamine synapses. It is also believed that schizophrenics may have an increased number of dopamine receptors. This hypothesis was supported by a study published in the journal Science in 1984. Glutamate is a neurotransmitter that affects learning and memory. Lowered levels of it have been found in the brains of schizophrenic patients.
Frontal Lobe and Poor Insight
Many schizophrenics are not aware that they suffer from a mental illness. This deficit is known as “poor insight” and has been linked to frontal lobe deficits. A study published in volume 13 of the Journal of Neuropsychiatry and Clinical Neuroscience in 2001 found an inverse correlation between poor insight and frontal lobe volume in schizophrenics. The patients who were least aware of their problems had the smallest frontal lobes.
References
- National Institute of Mental Health: Schizophrenia
- Proc Natl Acad Sci: Mapping adolescent brain change reveals dynamic wave of accelerated gray matter loss in very early-onset schizophrenia
- Schizophrenia Bulletin: Patterns of Structural MRI Abnormalities in Deficit and Nondeficit Schizophrenia
- British J. of Psychiatry: Amygdala volume in schizophrenia
- "Neuropsychopharmacology, Proceedings Fifth Collegium Internationale Neuropsychopharmacologicum"; Rossum; 1979
