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Unformatted text preview: BioNB222 Spring 2008 Cornell University Ronald Harris-Warrick 1 Lecture 14. Psychiatric Diseases Reading Assignment None. Summary: The major psychoses (schizophrenia, major depression and manic-depressive illness) are psychiatric diseases whose etiologies have a very significant biological and genetic component. Schizophrenia is the more severe of these illnesses, causing fundamental changes in the thought process itself. It is not multiple personality disorder, but rather shows a split between the rational and emotional minds as well as a series of other positive and negative symptoms. Lecture Outline Understanding the defects in neural diseases is important for two reasons. First, we wish to alleviate suffering and come up with new treatments for disease. Second, defects in neural function often give us unique insights into the mechanisms of normal neural function. Today, we will discuss three diseases that affect normal human cognitive function, for which we do not know the underlying defects but we do have relatively good drug treatments: schizophrenia, depression and bipolar (manic-depressive) disorder. A. Schizophrenia Schizophrenia is a debilitating cluster of diseases affecting about 1% of the population. It is characterized by several major clinical signs: 1)disturbed form and content of thought, including rapid and illogical thinking and bizarre delusions of persecution; 2) hallucinations, usually auditory; 3) a mood disorder, where emotions are absent or inappropriate to the situation; 4) motor alterations leading to purposeless activity or periods of immobility; 5) changes in social function, with gradual withdrawal from social interactions, and breaking of normal social conventions. The bizarre delusions and hallucinations are called positive signs (because they appear to be an excess of mental activity over normal) and are more frequent in early onset of the disease. The apathy, blunted affect and social withdrawal are called negative signs (a decrease in normal mental activity) and are increasingly disabling with time. Onset is typically in the late teens or early 20's. There is a clear genetic component to the disease, with concordance rates of 48% between monozygotic twins, but only 17% between dizygotic twins. A number of brain defects have been detected or hypothesized to explain the symptoms of schizophrenia. First, CAT scans show a relatively reproducible ventricular enlargement, suggesting a loss of nervous tissue. In particular, there 2 appears to be loss of matter on the left temporal lobe, including the amygdala, hippocampus and associated cortical regions. There is also hypoactivity in the associated frontal lobes during cognitive tasks such as working memory tasks....
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This note was uploaded on 04/30/2008 for the course BIO 2220 taught by Professor Hopkins,c.d. during the Spring '08 term at Cornell.
- Spring '08