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What do twin studies consistently show regarding concordance rates in identical versus non-identical twins?
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Identical twins - 46% concordance
Non-identical twins - 14 % concordance
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What are the likely rates of schizophrenia among relatives of an individual with schizophrenia?
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One parent - 5-6%
One sibling - 10%
One sibling and one parent - 17%
Two parents - 46%
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Know the candidate susceptibility genes associated with schizophrenia.
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Neuregulin 1 (GABAergic, Glutamatergic neurotransmission)
Dysbindin
Catechol-o-methyltransferase (COMT)
Disrupted-in-schizophrenia (DISC)
Brain-derived neurotrophic factos (BDNF)
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Schizophrenia epidemiology
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Affects 1% of world population
Lifetime prevalence 0.5 - 1.5% (males = females)
Men - mean onset age 15 - 25
Women - mean onset age 25 - 35
Rate of homelessness 4 - 16%
50% inpatient admissions, 25% inpatient beds
DALYs 15-44
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Identify the most consistent anatomic/structural finding in schizophrenia.
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?
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4 main dopamine pathways
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Nigrostriatal pathway - VTA to caudate and putamen; rich in D1 and D2 receptors that cause Parkinson-like symptoms when blocked with anti-psychotics
Mesocortial pathway - VTA to diffuse cortical connections; responsible for the negative symptoms of schizophrenia
Mesolimbic pathway - VTA to amygdala and hippocampus; responsible for positive symptoms of schizophrenia
Tuberoinfundibular pathway - hypothalamus to pituitary gland; causes increased prolactin
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Positive symptoms of schizophrenia
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Thought content symptoms - impaired reality testing, delusions, hallucinations
Thought process symptoms - loosening of associations, tangentiality, 'derailed'/disorganized speech, behavior and incongruous affect
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Negative symptoms of schizophrenia
(the 5 "A's")
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Affective flattening
Alogia - poverty of speech, content, blocking
Avolition/apathy - impaired grooming, work, school performance
Anhedonia/associality
Attention - social inattentiveness
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Choosing an antipsychotic agent
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Most important to target specific symptoms!
Patients with agitation, impulsivity, confusion respond in hours to weeks.
Patients with auditory and visual hallucinations respond in weeks.
Patients with delusions, social withdrawal, lack of motivation, flat affect, and impoverished speech may not respond at all.
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Temporal differentiation of psychotic disorders
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Schizophrenia - greater than six months
Schizophreniform disorder - one to six months
Brief psychotic disorder - one day to less-than one month
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DSM criteria for schizophrenia
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Characteristic symptoms (2 or more) significantly persistent during a one-month period:
1. Delusions
2. Hallucinations
3. Disorganized speech (derailment/incoherent)
4. Grossly disorganized or catatonic behavior
5. Negative symptoms (flat, alogia, avolition)
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Grandiose delusions
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Possessing wealth or great beauty or having special ability (ex. extrasensory perception); having influential friends; being an important figure
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Nihilistic delusions
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Believing that one is dead or dying; believing that one does not exist or that the world does not exist
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Persecutory delusions
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Being persecuted by friends, neighbors, or spouse; being followed, monitored, or spied on by the government or other important organizations
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Somatic delusions
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Believing that one's organs have stopped functioning or are rotting away; believing that the nose or another body part is terribly misshapen or disfigured
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