Biological Explanations Flashcards
How are candidate genes involved in SZ?
- early research looked for a single gene involved
- found to be polygenic
- Ripke (2014) —> genetic makeup of 37,000 ppl compared w 113,000 controls
- found 108+ genes associated w higher risk of SZ
- aetilogically heterogenous = caused by diff combos of genes
How are genetics involved in SZ development?
- found to have a genetic basis; chance of developing SZ increases w genetic similarity to someone w disorder
~ MZ twins : 48%
~ DZ twins : 17%
~ general population : 1%
What are neural correlates?
Measuring structures/function of the brain that correlates with a behaviour or experience
Outline the dopamine hypothesis
- suggests dysregulated dopamine system contributes to positive, negative and cognitive symptoms of SZ
- can be hyperdopaminergia (too high) or hypodopaminergia (too little)
Describe the neural correlate for high levels of dopamine
Hyperdopaminergia
- area : subcortex, specifically between dopamine pathways and Broca’s area
- function of area : speech production
- symptom : speech poverty + auditory hallucinations
Describe the neural correlate for low levels of dopamine
Hypodopaminergia
- area : prefrontal cortex
- function of area : responsible for logical thinking and decision-making
- symptoms : negative symptoms (e.g. avolitions)
Describe the neural correlate leading to symptom of abolition
Ventral striatum = involved in process of motivation and reward
Outline research supporting neural correlates
Juckel et al
- finding 1 —> activity levels (fMRI) in ventral striatum were lower in SZ than controls during reward anticipation
- finding 2 —> lower activity levels in ventral striatum correlated w severity of neg symptoms
What are issues with biological explanation of SZ?
Biologically reductionist
- only focuses on genetic, neuro chemical and brain structural components
- ignored other potential factors
- e.g. trauma (67% of SZ patients reported traumatic event vs 38% in other non-psychotic mental health issues), smoking cannabis (x7 risk), family environment, birth complications
- MZ twins are not 100% so cannot be entirely genetic
Bidirectional ambiguity
- unclear whether altered dopamine levels cause SZ or whether experience of SZ results in altered dopamine regulation
What are strengths of the biological explanation of SZ?
Treatments
- genetic counselling —> helps people understand genetic condition in family, helps making choices about having children or future development of SZ
- typical and atypical antipsychotics —> block dopamine receptors at synapse, reduce action of dopamine
- success of treatments suggests dopamine is involved in SZ symptoms
however
- some atypical psychotics also work on serotonin and glutamate
- some post mortem + brain scans found high levels of glutamate in SZs
- suggests DA hypothesis = incomplete as other neurotransmitters involved