If SZ has genetic basis
62 SZ patients (31m, 31f) All hospitalised before 1964. 24 MZ twins, 33 DZ twins identified using eg blood grouping.
- Hospital notes
- Semi structured interviews with twins and parents
- 30 min tape recording of speech
- Personality tests
- Psychometric tests
- 42% MZ twins, 9% DZ twins diagnosed with SZ
- Average rate of SZ in general population was 1% therefore, person that is a MZ twin is 42 times more likely to have SZ
Closer genetic link, more likely twins have SZ. But MZ concordance rate was below 100% so genes may lead to liability towards SZ but needs to have environmental trigger.
Low - only used SZ twins that were hospitalised before 1964 so not representative of non-twin population so results of SZ basis won't apply completely
High - Quant data collected in terms of % of twins with SZ to make comparisons so can help understand SZ basis
High - wanted to study relation between genetics and SZ using MZ and DZ twins (controlled variables)
Low - can allow bias to occur when listening to SZ patients tape recordings therefore SZ basis could be misinterpreted
Can carry out further research to understand how genes are involved in SZ
Difficult to separate nature vs nuture as SZ basis so can only find relationship
Finding genetic basis in SZ by comparing adoptive and biological family of SZ patients
- 34 SZ patients (mostly DZ twins) taken from Danish Adoption Register, aged between 20-43.
- Split into 3 groups: Chronic sufferer, Short-term sufferer, borderline diagnosis
- Matched to 33 non-SZ adoptees based on age of adoption and gender and social class of adoptive family
- Used Danish family records, tracked down 463 records. Used mental health register to assess mental status.
- Relatives diagnosed by psychiatrists who were unaware of the relation to patient (blind test)
- Diagnosed into 3 categories: B (alike adoptive child), C (inadequate personality), D (diagnosis unclear)
- More signs of SZ in both adoptive child and their biological family than adoptive family.
- More SZ found in adoptive biological family that control biological families
- Out of 150 biological relatives, 8.7% had SZ or inadequate personality compared to 1.9% in biological families of control sample.
- SZ has genetic component.
- Adoptive sample had more SZ in biological families than control sample
Low - only used SZ twins from Danish adoption agency so results of SZ basis not representative of other countries like UK
High - collect quant data in terms of % of adoptive children with SZ to be compared to biological parents, objective, can gain better understanding of SZ basis.
High - Less open to bias from psychiatrists about link between genes and SZ using adoptive twins, ppt and psychiatrist variables controlled, high validity
Low - collecting quant data won't produce result of why there is a genetic link or specific types of SZ therefore limited explanation of SZ basis as only shown in twins
Extra help can be offered to adoptive families who adopt child with family history of SZ
Could lead to discrimination of children up for adoption as they would be less likely to be adopted
Involved in higher cognitive functioning like problem solving, decision making, reasoning including motor skills and expressive language
Information processor like processing language
Visuospatial processing, colour differentiation and motion perception
Hearing some aspects of language and memory making
Motor control co-ordination of movements, motor learning
Transmission of nerve signals from body to brain
- Sensory stimulus from right side of body
- Motor control of right side of body
- Speech, language, comprehension
- Analysis, calculations
- Time and sequencing
- Recognition of words, letters, numbers
- Sensory stimulus from left side of body
- Motor control of left side of body
- Creativity, spatialability
- Context, perception
- Recognition of faces, places, objects
Connects two hemispheres and enables communication between the two ("information highway")
Brain relay station, passes on information from senses
Regulates eating, drinking, release of sex hormones (testosterone, oestrogen)
Processes emotional responses, memory, decision making
Memory consolidation, navigation, spatial awareness
Processes movement information and planning responses, linked to habit learning and reward
- Multiple X-ray images of the brain from different angles.
- Researchers examine structure of brain "slice by slice" making cross sections.
- 3D images created from large series of 2D images
- Radioactive tracer containing glucose (metabolised by body) injected into bloodstream.
- Positrons in tracer send signals to scanner, records level of brain activity.
- 3D images made
- 2 scans carried out (active and inactive) to make comparisons of activity during task
- Scans colour coded to indicate areas of high/low glucose metabolism
- Measures brain function by looking at blood flow detecting changes in level of oxygen delivered to brain.
- Scan monitors changes in blood texture and colour delivered to brain.
- Most active areas where blood is oxygen rich
High - Standardised, measuring biological functions within the brain eg measuring metabolism of glucose, can replicate to check for consistency
High V - objective, which means there won't be any interpretation bias therefore more accurate measure
Low - Carried out in controlled settings rather than the natrual environment meaning that less accurate as brains will function differently when in a natural setting
Low - The images taken from the scans may need to be interpreted by researchers meaning subject to intepretation bias, less accurate
Allows us to detect problems in the brain like TBI so then we can develop treatment programmes
Reductionist, like assumption that criminal behaviour is due to the brain and doesn't consider environmental factors