Chapter 16 Schizophrenia and Affective DisordersPresentation Transcript
Chapter 16 Schizophrenia and Affective Disorders
A serious mental disorder characterized by:
Delusions of persecution or grandeur
Hallucinations (mostly auditory)
Behaviors (withdrawn or detached, odd movements))
Positive symptom: (known by their presence)
delusions, hallucinations, abnormal movements, or thought disorders.
Negative symptom: (characterized by absence)
social withdrawal, lack of affect, and reduced motivation.
Heritability: In its simplest form, if schizophrenia was determined by a single dominant gene, about 75% of children from schizophrenic parents would get it. If it was recessive, about 50% would inherit the disorder. An incidence less than 50% suggests that the disease is determined by multiple genes and that only a susceptibility is passed on.
Evidence for heritability
Most studies suggest between 25-40% in identical twins and about 5-20% in fraternal twins.
Clearly, the environment is an important contribution.
Dopamine Hypothesis: schizophrenia is caused by excessive dopamine activity in the mesolimbic system.
Supporting evidence: drug treatment, amphetamine psychosis, treatment for Parkinson’s disease
Additional evidence: increased DA activity, increased D3 & D4 receptors in mesolimbic system,
Pharmacology of Schizophrenia
Chlorpromazine: A phenothiazine
A “typical neuroleptic”; a nonspecific dopamine receptor blocker; first prescribed antischizophrenic drug.
An “atypical neuroleptic”; an antipsychotic drug that blocks D 4 receptors in the nucleus accumbens. Little effect on D2 receptors