Is Schizophrenia
Associated With A Chemical Defect In The Brain?
Basic knowledge about
brain chemistry and its link to schizophrenia is
expanding rapidly. Neurotransmitters, substances that allow communication
between nerve cells, have long been thought to be involved in the development
of schizophrenia. It is likely, although not yet certain, that the disorder is
associated with some imbalance of the complex, interrelated chemical systems of
the brain, perhaps involving the
neurotransmitters dopamine and glutamate. This
area of research is promising.
Is Schizophrenia Caused By A Physical Abnormality In The Brain?
There have been dramatic advances in neuroimaging technology that permit
scientists to study brain structure and function in living individuals. Many
studies of people with schizophrenia have found abnormalities in brain
structure (for example, enlargement of the fluid-filled cavities, called the
ventricles, in the interior of the brain, and decreased size of certain brain
regions) or function (for example, decreased metabolic activity in certain
brain regions). It should be emphasized that these abnormalities are quite
subtle and are not characteristic of all people with schizophrenia, nor do they
occur only in individuals with this illness. Microscopic studies of brain
tissue after death have also shown small changes in distribution or number of
brain cells in people with schizophrenia. It appears that many (but probably
not all) of these changes are present before an individual becomes ill, and
schizophrenia may be, in part, a disorder in development of the brain.
Developmental neurobiologists funded by the National Institute of Mental
Health (NIMH) have found that schizophrenia may be a developmental disorder
resulting when neurons form inappropriate connections during fetal development.
These errors may lie dormant until puberty, when changes in the brain that
occur normally during this critical stage of maturation interact adversely with
the faulty connections. This research has spurred efforts to identify prenatal
factors that may have some bearing on the apparent developmental abnormality.
In other studies, investigators using brain-imaging techniques have found
evidence of early biochemical changes that may precede the onset of disease
symptoms, prompting examination of the neural circuits that are most likely to
be involved in producing those symptoms. Meanwhile, scientists working at the
molecular level are exploring the genetic basis for abnormalities in brain
development and in the neurotransmitter systems regulating brain function.
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