Biological explanations of SZ Flashcards
who studied concordance rates of genetics?
Gottesman (1991)
What is the concordance rate of SZ in the ‘normal’ population?
1%
What is the concordance rate of SZ for the offspring of 1 SZ grandparent?
5%
What is the concordance rate for the offspring of 1 SZ parent?
13%
What is the concordance rate for dizygotic twins?
17%
What is the concordance rate of monozygotic twins?
48%
What did Joseph (2004) calculate?
All pooled twin studies before 2001 showed a concordance rate of 40.4% for MZ twins and 7.4% for DZ twins
What is the issue in concordance rates genetically?
similar genes = similar environment
esp true for MZ twins
but ethical issue of controlling ones environment
What did Tienari (2000) study?
Finnish adoption study?
What is the methodology of Tienari’s study?
164 adoptees whose biological mothers had SZ compared to a control of 197 adopted children with no SZ mother.
(all separated from mother by age 4, all aged 5-7)
How many children in the control group developed SZ? Why is this significant?
4 (2%), similar to normal concordance therefore adoption is not a risk factor for SZ
How many of children whose mothers had SZ developed it? What does this tell us about genetic factors?
11 (6.7%), genetics play a role in the development of the disorder and match concordance rates of prev studies
What is a weakness of adoption studies?
Adoptees may have been selectively places in an environment similar to prev background, cannot be sure about genetics
Who further analyzed Tienari and what did they find?
Wahlberg et al. (2000) found at-risk children did ‘better’ than those in less supportive environments (nurture vs nature)
What is schizophrenia known as for its genetic makeup?
A polygenetic disorder.
Who studied the genes of SZ?
Ripke et al. (2014) anaylsed more than 150,000 people and found over 100 genetic regions that contribute to SZ
What gene is the most important atm?
DRD2 - gene encoding the dopamine receptor where all drugs are currently targeting
What is the model called taking the nature and nurture of a disorder into consideration?
The diathesis-stress model
What are the 4 parts to neural correlates?
The dopamine hypothesis
Areas of the brain
grey and white matter
ventricles
What is the term for the excess of dopamine?
hyperdopaminergia
What is the term for too little dopamine?
hypodopaminergia
What happens when there is an excess of dopamine in Broca’s area?
responsible for speech production - associated with poverty of speech and/or auditory hallucinations
What are the two drugs that increase dopaminergic activity?
Amphetamines
L-dopa
What do amphetamines do?
release dopamine at central synapses, known to trigger SZ-like symptoms or make it worse in known SZ.
What does L-dopa do?
L-dopa is converted into dopamine to relieve symptoms of parkinson’s disease
What drugs decrease dopaminergic activity?
Clozapine
Neuroleptic drugs
What does Clozapine do?
block dopamine which reduces symptoms
Who researched the effectiveness of neuroleptic drugs?
Davidson & Neale (1996)
Who proposed the revised dopamine hypothesis?
Davis and Kahn (1991)
What is the revised dopamine hypothesis?
low levels (hypodopaminergia) in the prefrontal cortex (thinking and decision making) cause negative symptoms
How is the prefrontal cortex related to SZ?
Mian area for executive control (planning, reasoning, judgement) is impaired in SZ
How is the hippocampus related to SZ?
in temporal lobe, deficits lead to working memory impairments and central cognitive impairment (Mukai et al. 2015) c
Why is grey matter significant in SZ?
Reduced grey matter especially in temporal and frontal lobes (Canon et al. 2014) found individuals at highs risk had steeper loss
Why is white matter significant in SZ?
reduced myelination particularly in neural pathways PFC and hippocampus
Why are ventricles significant in SZ?
Hartberg et al. (2011) found enlarged ventricles thought to be brain not developing properly.
