october 31, 2011
Chapter 10, schizophrenia.
-beginning of notes in notebook.
Gentic risk factors
-concordance rates: MZ twins:48 % and DZ twins:17%
-if both parents have schizophrenia:46% chance for offspring
-genes involved in regulaition of dopamine and serotonin activity
-polymorphism of neurotophins (proteins) involved in synapse creation and pruning, and
neuron development and survival
-cannabinoid receptor coding gene. (Binds with THC.)
Environmental risk factors. Genes are not enough, in cognition with environment
-exposure to influenza and other viruses during second trimester
-other birth complication, at birth or after
-urban environments, more stressful, higher paced life can cause schizophrenia
-immigration, people who immigrate have small increase in schizophrenia
-cannabis use. Been linked. Indivi who develop schizophrenia later in life often are seen to use
-physical and emotional abuse during childhood
-enlarged ventricles. Can cause extra pressure in brain and cause death of neurons
-reduced gray matter (prefrontal and temporal lobes) where the social cognition is. Smaller
brains. Less able to process information
-deficits in executive functioning and social cognition
-increased dopamine production in the midbrain (positive symptoms)
-decreased dopamine activity in the prefrontal lobe (negative symptoms)
-other neurotransmitters involved.
Course and Outcome. End results and how they are expressed
-single psychotic episode with remission and favorable outcome: 20-30%
-multiple episodes with (partial) remission in between: 30%
-chronic deteriorating course with increasing negative symptoms: 33%. require constant care
-using medication: 20-30%
-stop using medication: 70-80% within 3-7 months. Treatment
-institutionalization and behavior management prior to 1950s:
-prisons and mental institutions
-psychosurgery and ECT
-antipsychotic drugs (1950s)
-prevention of harmful behavior
-reduction in positive symptoms
-side effects: tardive dyskinesia, parkinsonism, dystonia, akathisisa.
-Second generation antipsychotics.
-reduction of negative symptoms
-higher response rate
-fewer side effects.
-lower suicide rate.
-disruptions to normal brain maturation during second trimester or at time of birth increase the risk for
schizophrenia later in life.
-check graph on slides.
-early neuronal disruption is followed by furthers disruptions to brain maturation and reorganization
-positive social stresstos (romantic relationships)
-nnegative social stressors (peer pressure)
-expressed emotion in the home (positive or negative)
-critical developmental stage in which development and reorganization slow down
-insufficient repair mechanism and reduced plasticity.
-second hit can lead to prodromal schizophrenia (not really schizophrenia) (e.g, delayed physical and
intellectual development; social withdrawal) and predict first psychotic episode in early adulthood.
-paradox: genes related to the schizophrenias continue to persist despite devastating effect on fitness
-onset occurs during peak reproductive years
-reduction in reproductive success 30-70%
-schizophrenia are a heterogeneous collection of disorders; single unifying explanation is unlikely
-variety of evolutionary hypotheses to explain evolutionary synthesis for schizophrenia
Group splitting hypothesis
-group selection argument: when groups reach critical size of 40-60 individuals, groups split into two.
-schizotypal personality (personality that reflects schizophrenia) is a born leader:
-delusions of grandeur, paranoia of outsiders
-charismatic leaders from history: rapidly shifting emotions, bizarre speech patterns, divine
-social conditions: large groups outgrowing their resources lead to deprivation, mutual
suspicion, hostility, and lack of cohesion
-new group coalesces around schizotypal leader and believes themselves chosen; initiate
hostility towards other groups
-leaders typically receive more/better mating opportunities
-genes associated with schizophrenia appeared before migration fromAfrica (similar rates
-genes have multiple effects and are expressed differently depending on what other genes are
-loss of fitness in schizophrenia individual is offset by fitness advantages
-superior social skill in relatives? No evidence
-resistance to infections diseas in relatives (typical of balanced polymorphisms) confirmed once
-reduced risk of cancer in relatives?
-Creativity or enhanced theory of mind in relatives?
-superior academic success
-link between creativity/intelligence and schizophrenia.
-sir isaac newton
November 4, 2011
Developmental disruption hypothesis
-sexual selection fitness indicators (SSFI): traits that signify high fitness(good genes or good
-examples. Peacocks tail; bilateral symmetry
-attractive because development is easily disrupted by mutations or by environmental hazards
-every SSFI must include low fitness unattractive extremes
-schizophrenia represents the low-fitness unattractive end of the extreme of an unspecified
mental SSFI. Maybe low theory of mind to enhance courtship behavior? Maybe theory of mind
to enhance intrasexual competition? Maybe its language.
-Schizophrenia is a polygenetic disorder that reflect