Biological explanations for Schizophrenia Flashcards
family studies - what did Kendler find
if a first degree relative has Sz you are 18 times more likely to develop it than the general population
family studies - what are the concordance rates for when 2 parents, 1 parents and a sibling have Sz, and who found them
2 parents - 46%
1 parents - 13%
sibiling - 9%, Gottesman
twin studies - what concordance rates did Joseph find
Mz twins - 40.4%
Dz twins - 7.4%
twin studies - what have more recent methodologically sound studies found
lower concordance rates than Joseph but Mz still have a higher concordance rate than Dz twins
adoption studies - how many adoptees did Tienari study (Sz and control group), how many received diagnosis of Sz (Sz and control group)
164 Sz adoptees, 197 control group
6.7% of Sz adoptees, 2% of control group
why do all concordance rates with regards to genetic factors support the biological explanation
they are all higher than 1% which is the general population risk of development
what does the dopamine hypothesis state
messages sent from neurones that transmit dopamine fire too easily/too often
what is an excess of dopamine in the brain associated with
positive symptoms of Sz
schizophrenics are thought to have abnormally _ numbers of _ receptors on receiving _ resulting in more _ binding and so more neurones _
schizophrenics are thought to have abnormally high numbers of D2 receptors on receiving post-synaptic neurones, resulting in more dopamine binding and so more neurones firing
what 2 drugs increase dopamine levels
amphetamine and L-dopa
what is amphetamine and what does it do
dopamine agonist, stimulates nerve cells containing dopamine causing a flood of dopamine in the synapse
what is L-dopa used for
Parkinson’s patients need it to increase dopamine levels, sometimes leads to the development of Sz symptoms
what drugs decreases dopamine levels and explain
antipsychotics - block dopamine activity in the brain and eliminate Sz symptoms
who revised the dopamine hypothesis
Davis and Kahn
what is the revised dopamine hypothesis
positive symptoms are caused by an excess of dopamine in the subcortical areas/mesolimbic pathway of the brain, negative symptoms are caused by a deficit of dopamine in the prefrontal cortex
_ et al used _ scans to assess dopamine in normal p’s and Sz p’s. he found _ levels of dopamine in the _ _ _ of Sz compared to normal p’s
Patel et al used PET scans to assess dopamine in normal p’s and Sz p’s. he found lower levels of dopamine in the dorsolateral prefrontal cortex of Sz compared to normal p’s
_ and _ depleted dopamine in _. they found _ _ which was reversible using _, an _ antipsychotic
Wang and Deutch depleted dopamine in rats. they found cognitive impairment which was reversible using olanzapine, an atypical antipsychotic
name 3 evaluation points for genetic factors
- common rearing patterns may explain family similarities
- Mz twins encounter more similar environments than Dz twins
- adoptees may be selectively placed
genetic factors evaluation- what did Joseph find with regards to adoptees being selectively placed
adoptive families in Denmark and the US are informed of the child’s genetic background, so perhaps families who adopt children with Sz in their background have an environment which may trigger the Sz, e.g. family dysfunction
genetic factors evaluation- common rearing patterns may explain family similarities…
negative emotional climates causes stress which triggers the onset of Sz. maybe the environment is the biggest factor in the onset, not heredity, there is a lot of evidence for the environment playing a role e.g. high EE makes p’s 4 times more likely to relapse
genetic factors evaluation- how do Mz twins encounter more similar environments
treated more equally and experience identity confusion
dop hyp evaluation - evidence from treatment came from _ meta-analysis of _ studies analysing _ and found…
Leucht et al, meta-analysis of 212 studies analysing the effectiveness of a placebo vs antipsychotic drugs. found drugs were more effective at treating pos and neg symptoms achieved through the normalisation of dopamine levels. if treatment works this proves the theory is correct
dop hyp evaluation - inconclusive supporting evidence from _ states that _ affect more _ than just dopamine. also other factors influencing an _ of dopamine aren’t considered such as _ and _
inconclusive supporting evidence from Moncrieff states that amphetamines affect more neurotransmitters than just dopamine. also other factors influencing an increase of dopamine aren’t considered such as smoking and stress
dop hyp evaluation - Noll claims there is _ _ _ for the revised+dopamine hypothesis. he argues antipsychotics don’t reduce symptoms in _ of people. _ symptoms can occur with _ dopamine levels so _ the _ receptors has _ effect, _ the hypothesis
Noll claims there is inconclusive supporting evidence for the revised+dopamine hypothesis. he argues antipsychotics don’t reduce symptoms in 1/3 of people. positive symptoms can occur with normal dopamine levels so blocking the D2 receptors has no effect, rejecting the hypothesis
