Introduction to Psychosis
Spring 1999
Table of Contents
- Introduction
- Positive and Negative Symptoms
- Causes
- Genetics/Anatomical Differences
- Biochemical
- Environmental
- Conclusion
-
Director's Letter
Introduction
Psychosis is a feature of a broad grouping of mental illnesses
associated with delusions, hallucinations, and serious defects in
judgment and insight. The most prominent psychotic disorder is
schizophrenia. This illness transcends cultures, socioeconomic and
racial backgrounds, with an incidence between 0.5 to 1 percent of
the entire world's population. This first stage of the disease usually
occurs between the ages of 15 and 30 and continues throughout
life.
The social and economic repercussions are exacerbated because of
the period of time that the disease strikes - when a person's social
and economic foundations are being laid. Illustrating the economic
impact, the calculable associated cost of the illness for the United
States alone is over 70 billion dollars per year.
Corresponding to the diversity of people with the illness, there is an
equally varied response to medications and other therapies. Studies
have shown that the prognosis is better for individuals who have a
sudden onset rather than a gradual onset of symptoms. Other
factors, such as having a positive and involved social structure, a
good work record, being older than 12 years of age during the
initial stage of the illness, and having healthy sexual and emotional
adjustment, point to a better probability of living with the disease
successfully.
Of the individuals diagnosed with schizophrenia, it is estimated that
a small portion will lead normal lives with the aid of medication, a
larger segment will experience recurring episodes, and another
group will deteriorate into chronic and disabling illness.
Unfortunately, between 10 and 25 percent of the total population
of people who suffer with the disease commit suicide, half within
the first few years of the onset of illness.
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Positive and Negative Symptoms
As the understanding of schizophrenia has progressed, researchers
have found it useful to distinguish between positive and negative
symptoms. The difference between the two categories may indicate
separate disorders within schizophrenia, and thus different
treatments. A widely held theory is that positive symptoms are
related to biochemical changes in the brain and negative symptoms
are indications of structural change.
Hallucinations, delusions, and disorganized thought processes are
examples of positive symptoms; symptoms that are exacerbated or
introduced by the disease. These symptoms are more responsive
than negative symptoms to conventional antipsychotic medication
such as chlorpromazine, clozapine, and haloperidol.
Negative symptoms are more chronic and do not respond as well
to traditional neuroleptics. These symptoms include emotional
withdrawal, decrease in mental capacity, loss of speech, and loss of
social drive and/or sense of purpose. In the past 10 years, newer
drugs, called atypical anti-psychotics, have become available and
may offer more benefit to those who have negative symptoms of
schizophrenia.
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Causes
There has been no identified single cause of schizophrenia. Instead,
researchers work within widely held theories that genetic
inheritance plays a strong role, with a multitude of possible events
influencing the onset of the disease. These include genetic,
anatomical and biochemical factors as well as psychological, social,
and environmental circumstances. In this section, broad overviews
will be cited with more in-depth exploration given in future issues of
the newsletter.
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Genetics/Anatomical Differences
There is no question that genetic predisposition plays a strong role
in schizophrenia. The problem facing researchers is that the genetic
aberrations may be on multiple chromosomal sites. There have
been studies linking possible genetic predisposition to schizophrenia
on chromosome 6, 8, and 22, but all have fallen short of proving a
direct correlation to the associated schizophrenic symptoms.
New research continues to support a genetic basis for
schizophrenia. In the January 4, 1999 publication of the Lancet
(353:30-33, 1999) a study reported that the unaffected relatives of
schizophrenic patients had smaller left hippocampo-amygdala (the
area of the brain involved with memory and emotion) compared to
people who did not have a blood relative with schizophrenia.
Other anatomical differences have been observed in the brains of
patients with schizophrenia, although researchers are not sure which
irregularities produce specific outcomes. For example, as a group,
patients with schizophrenia have larger ventricles, which are cavities
in the brain filled with spinal fluid, which contains nutrients,
hormones, and white blood cells. Patients with larger ventricles
tend to have an increased prominence of negative symptoms.
Another possible anatomical factor influencing schizophrenia may
be the reduction in the brain's cerebral cortex volume. As study
reported in the Archives of General Psychiatry (52:805-820,
1995) showed that the reduction is due to the diminished number of
dendrite fibers and synapses, the communication pathways
between brain cells, which in turn decreases the volume of the
cortex.
One explanatory theory is that the connections between the brain
cells are pruned before birth, causing the brain's cells to pack
closer together to communicate with each other. During
adolescence when natural pruning occurs, the already reduced
pathways are again trimmed. This may explain why the onset of
schizophrenia usually occurs during adolescent/young adult period.
In addition to the finding of decreased volume of the cerebral
cortex and enlarged ventricles of the brain, another study focused
on abnormalities in the brain related to motor function. In this study
researchers used a battery of mechanical tests to determine if there
was a relation between the patients' lack of motor control to their
disease. They found a correspondence between left hemisphere
dysfunction in people with schizophrenia and right hemisphere
dysfunction in people with bipolar disorder.
The VISN22 MIRECC has a molecular biology laboratory that
operates within the Neuroscience Research Unit to support
investigators working in the field of schizophrenia genetic research.
Currently, the laboratory is creating animal models that reflect the
physical differences seen in patients with schizophrenia.
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Biochemical
There are biochemical changes that occur in the brain as well as
anatomical differences. These may have genetic origins such as a
protein not being manufactured or too much of a chemical being
produced. A primary example would be the chemical messenger
dopamine, which acts as a chemical bridge between the brain's
neurons (impulse conducting cells). It is believed that people with
schizophrenia either have an increased amount of dopamine of have
a heightened sensitivity to the chemical.
VISN 22 MIRECC researchers have begun a core study
comparing the effectiveness of the drug risperidone to olanzapine in
neuro and social cognition. Currently the study is settup up
protocols and laying the administrative foundation to begin calling
for patient volunteers. The results of this study may provide
physicians with insights into the medications, better enabling them to
use the information to more effectively treat patients with
schizophrenia.
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Environmental
Environmental factors may also play a role in developing
schizophrenia. Studies have shown that viral infection during
pregnancy (such as influenza), poor nutrition, different rH factors
between mother and father, and/or birthing complications may
increase the baby's risk for developing schizophrenia.
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Conclusion
Schizophrenia research is progressing quickly, in part because
government agencies are beginning to recognize the impact the
disease has on the economic and social health of society.
The VISN 22 MIRECC website and newsletter MindView will
continue to act as a resource for professional and lay individuals
who want to learn more about psychotic disorders. Future articles
will bring in-depth coverage of the latest research.
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