Bio exp for sz

• -sz is heritable/inherited through the generations through transmission of genes - runs in families 
• What’s the family studies?

  -Find individuals with schizophrenia and determine whether their biological relatives are similarly affected more often than non relatives 

  -gottesman (1991) found that children with 2 sz had a concordance rate of 46% and those with 1 sz parent 13% and siblings had 9%
• What’s the percentage of genetic similarity increases of the probability of sharing sz ?

  Misygotic twins have 48% chance wheras dizygotic twins has a 17% chance 
• What did the twin studies find ?

  If mz twins are more concordant than dz twins it suggests that the similarity is due to genes.A meta-analysis of twin studies conducted before 2001 found a combined concordance rate of 40% for MZ twins and 7% for DZ twins (Joseph 2004)
• What did the adoption studies found?

  Studies of genetically related individuals who have been reared separately.Tienari et al (2000) found that of 164 adoptees with schizophrenic mothers 11 (6.7%) also recieved a diagnosis,compared to just 2% of the 197 control adoptees.
• What’s the information for candidate genes ?

  -Early research looked for a single genetic variation in the belief that one ‘faulty’ gene could explain schizophrenia

  -HOWEVER, schizophrenia appears polygenetic

  -Most likely genes being those that code for neurotransmitters (including dopamine) (later discussion of dopamine hypothesis)

  -Different studies have identified different candidate genes suggesting that schizophrenia is aetiologically heterogenous
• What did neural correlates say?

  Patterns of structure or activity in the brain that occur in conjunction with an experience and may be implicated in the origins of that experience 

  -dopamine hypothesis 
• What’s the dopamine hypothesis?

  The original dopamine hypothesis claims that an excess of the neurotransmitter dopamine in certain regions of the brain is associated with the positive symptoms of sz.This is the sub cortical regions of the brain 
• What has further research suggested about the dopamine hypothesis?

  Sz are thought to have abnormally high numbers of D2 receptors of receiving neurons,resulting in more dopamine binding and therefore more neurons firing 
• What’s the revised dopamine hypothesis? (Davis et al)

  -excess of dopamine in the mesolimbic pathway which causes positive symptoms 

  -deficit of dopamine in areas of the prefrontal cortex which is the area responsible for thinking,decision making etc,causes negative symptoms.
• What’s the evidence for revised dopamine hypothesis?

  -neural imaging - Patel et al 

  -used PET scans and found lower dopamine levels in dorsolateral prefrontal cortex of SZ compared to normal controls
• Biological therapies are effective

  -E Atypical antipsychotics are also effective, and Meltzer et al concluded that clozapine is more effective than typical antipsychotics and is 30-50% more effective in treatment-resistant cases

  -E Furthermore, Thornley et al did a meta analysis of 13 trials and found that chlorpromazine was associated w better functioning and reduced symptom severity compared to a placebo

  -L Therefore, there is research support for the effectiveness of biological therapies
• There are severe side effects of biological therapies

  -E Typical antipsychotics are associated with dizziness, agitation, sleepiness, weight gain, and long term use can lead to lip smacking and grimacing/tardive dyskinesia due to dopamine supersensitivity

  -E One of the most serious side effects is neuroleptic malignant syndrome (NMS), a result of blocking dopamine actions in the hypothalamus, which can be fatal due to disrupting regulation of several body systems

  -L Therefore,atypical antipsychotics may be better than typical antipsychotics because they have less side effects
• There is evidence to suggest that biological therapies do not actually cure SZ.Supportive research for SZ is flawed as Healy suggested that data from successful trials have been published multiple times, exaggerating the positive effects, and most studies also only review short term effects.
• bio para (2)

  As most antipsychotics also have a calming/sedative effect, its easy to demonstrate they have had a positive reaction as they appear calmer, but we may be treating the symptoms rather than the actual root cause.Therefore, biological therapies like antipsychotics may only relieve symptoms rather than curing SZ