Breakthrough Shines Light On Cause of Schizophrenia
January 29, 2016
On Wednesday, January 27, a team of American scientists at Harvard University Medical School and Boston Children’s Hospital, both in Boston, Massachusetts, published a study on the first clear evidence on the cause of schizophrenia, one of the most common and devastating forms of mental illness. The study identifies certain genes that are associated with the development of schizophrenia and proposes a mechanism by which the action of these genes causes the disease. The landmark study provides crucial new information on the molecular foundation of schizophrenia. The scientists hope this will serve as an important first step in the development of new and effective treatments for schizophrenia over the coming decades.
Schizophrenia is one of the most common mental disorders, affecting about 1 percent of the world’s population. It is characterized by unpredictable mental disturbances. People who have the disease sometimes withdraw from reality and think in illogical, confused patterns. Many people with schizophrenia develop delusions or hear “voices” that others cannot hear. They often suffer disturbances in mood and behavior. Some patients seem to feel no emotions, but others may display inappropriate emotions, such as laughing at sad situations. Some patients withdraw from their family and friends and talk mainly to themselves or to their “voices.”
Physicians do not know the exact cause of schizophrenia. A genetic component to the development of the disease has long been suspected because schizophrenia often runs in families. But no clear genetic cause had been discovered and environmental factors—including stress or a traumatic emotional experience—are known to influence the development of schizophrenia.
Medical imaging studies show that schizophrenics have less neural tissue in their brains than healthy individuals. This loss of brain tissue is especially apparent in regions of the frontal lobes, responsible for controlling short-term memory and behavior. Studying both humans and mice, the researchers identified a particular gene, called compliment component 4 (C4), that functions to delete connections between neurons (nerve cells) in the brain. As people grow from infants to adults, millions of neuron connections are established and deleted in the developing brain, in a normal process that scientists call “synaptic pruning.” (A synapse is the place between nerve cells at which nerve impulses are passed.) This pruning is especially active and important in the developing brain of adolescents and is finished by adulthood. Using genome databases, the scientists compared the C4 gene in 28,800 people with schizophrenia from 22 countries to 36,000 people without the disease. Through this analysis, the scientists identified a variation of the C4 gene that seems to be associated with schizophrenia. This variation of the C4 gene seems to be responsible for an abnormally high amount of synaptic pruning in adolescents, so that too many neurons and neural connections are deleted, leading to schizophrenia.
Other Links
- The National Institute of Mental Health—Schizophrenia
- PBS—”Nova:” What Schizophrenia Can Teach Us About Ourselves