Schizophrenia Flashcards
What is schizophrenia
Disorder of thought and mind
What is the incidence of schizophrenia
About 1%
What are the three types of symptoms of schizophrenia
Negative
Cognitive
Positive
What are negative symptoms of schizophrenia?
Poverty of speech [alogia], Low initiative [avolition], Apathy
Social withdrawal, Anhedonia
What are cognitive symptoms of schizophrenia?
difficulty with sustained attention
low psychomotor speed
Deficits in learning and memory
Poor abstract thinking and problem solving
What are positive symptoms of schizophrenia?
Delusions [beliefs that are contrary to reality]
Hallucinations [perceptions that occur in the absence of stimuli]
Thought disorder [disorganised and irrational]
What have adoption studies shown about schizophrenia
Adopted adult schizophrenics are likely to have schizophrenic biological relates
What have twin studies shown about schizoophrenia?
Concordance rates are higher for identical than fraternal twins
What is believed to be the role of genes in schizophrenia
May pass on susceptibility to develop schizophrenia
What are the two major hypotheses as to etiology of schizophrenia?
- Dopamine hypothesis [positive symptoms are consequence of over activity of brain dopaminergic synapses]
- Atrophy of brain [explain negative symptoms]
What was originally identified as effective antipsychotic agent?
Chlorpromazine
What does chlorpromazine do?
blocks DA receptors [D2]
What do drugs that block DA receptors do?
reverse schizophrenia
What do amphetamines do
release DA - produce positive symptoms of schizophrenia
Where is dopamine overactivity likely to be located in schizophrenia?
in mesolimbic pathway
What is the pathway in mesolimbic pathway that’s essential for reinforcement?
Ventral tegmental to nucleus accumbens
What are possible causes of increased DA transmission in schizophrenics?
Increased DA release
Increased postsynaptic response to DA release
Prolonged activation of postsynaptic receptors
What are the three ways that DA release can be increased in transmission?
More excitatory input to DA neurones
Less inhibitory input to DA neurones
Fewer or defective autoreceptors on DA neurones
What are the two ways that postsynaptic response to DA release in transmission can be increased?
More postsynaptic DA receptors
Greater response in postsynaptic neurones to activation of DA receptors
How can DA postsynaptic receptors be activated longer?
Decrease reuptake of DA by DA terminal button
Why is it difficult to discover the cause of increased DA transmission in schizophrenia?
Probably different for different patients
What does chlorpromazine do to postsynaptic receptor?
Biologically inert - doesn’t open a channel, blocks it instead tf reducing dopamine pathways
What does amphetamine do to neurotransmitters?
promotes release and inhibits uptake
What was effect of amphetamine dose on striatum of schizophrenics?
Greater release of dopamine [shown in PET studies], related to the increase in positive schizophrenia symptoms
What have studies of dopamine receptors in schizophrenic brains shown?
Postmortem studies suggest increased D2 receptors in striatum
- may be due to exposure of anti-psychotic drugs
- could be wrong site
- schizophrenia may be related to D4 or D3 sites
What do antipsychotic medications do for schizophrenia?
diminish the thought disorder
What causes the negative symptoms of schizophrenia?
Brain damage
What are neurological signs evidence in schizophrenia
eye tracking problems
catatonia
problems with blinking, eye focusing and visual pursuit
Describe brain ventricles in schizophrenics?
Enlarged
What do enlarged brain ventricles indicate?
loss of brain cells
What are the abnormal regions of schizophrenic brain?
Prefrontal cortex
Medial temporal lobes
Medial diencephalon
What prenatal events might cause brain damage in schizophrenia?
Birth trauma
Viral infections that impair neural development during second trimester
Nutritional issues
Maternal stress [compromising immune system of mother]
Shared placenta vs separate placenta
When are people with schizophrenia more likely to be born
late winter or early spring
WHat is hypofrontality?
decreased activity of dorsolateral prefrontal cortex [behavioural flexibility - card sorting tasks]
What relationship does PCP have with NMDA receptors
indirect antagonist [in dlpfc]
What are NMDA receptors?
most common glutamate receptors
What does PCP to do excitatory glutamate receptors?
Antagonises them, particularly in dorsolateral prefrontal cortex, and reduces dopamine usage in the area [decreased capacity]
[different in mesolimbic area]
What are the negative and positive symptoms produced by PCP?
underactivity in prefrontal cortex
overactivity in nucleus accumbens
What does PCP do to nucleus accumbens?
results in positive symptoms of schizoprenia [increased activity]
What do new antipsychotic drugs like clozapine and aripiprazole do as treatment for schizophrenia?
improve both positive and negative symptoms
reduce dopamine release in mesolimbic system
increase it in the PFC
