BIOLOGICAL APPROACH
ASSUMPTIONS
Thinking and behaviour are strongly determined by biological factors: structure and functioning of the nervous system.
GENETIC FACTORS
GENETIC BASIS
Genes code for characteristics such as eye colour but also for the structure of the nervous system and for the functioning of the nervous system
Heredity is the passing of characteristics from one generation to the next via the genes.
TWIN STUDIES
To determine the involvement of genetic factors
Concordance rate of MZ twins for depression was 46% and 20% for DZ twins
GENOTYPE & PHENOTYPE
GENOTYPE = Genetic makeup of an individual
PHENOTYPE = physical representation that results from the individual's genotype (e.g. eye colour)
PKU
Genetic disorder affecting ability to breakdown substance (phenylalanine) contained in normal foods
If following a strict diet, the phenotype will be normal intelligence and behaviour
If following diet containing the substance, it will accumulate in the brain and lead to a different phenotype - e.g. learning difficulties
Presence of particular genes might lead to different outcome depending on the social environment
Characteristics depend upon an interaction between nature (the genes) and nurture (the environment).
APPLICATION
Understanding the role of neurotransmitters has led to the development of drugs which are effective in the treatment of mental disorders such as schizophrenia and depression
Drugs are not effective for all patients and they can have serious side effects and they do not cure the disorders as if the patients stop taking the drug the symptoms reappear
EVALUATION
EVOLUTION
Darwin proposed theory of natural selection - genetically determined characteristics that enhance our chances of survival and reproduction will be passed onto the next generation
Traits which do not enhance survival will gradually disappear
e.g. Bowlby's theory of attachment
Twin studies don't separate nature and nature - they're raised in the same environment, so differences in concordance rates between MZ and DZ twins could be due to the fact that MZ twins are treated more similarly
No 100% concordance rates in MZ twins for mental disorders - environmental and social factors must be involved in development of these disorders
Irl Applications - psychoactive drugs developed to treat mental disorders due to understanding of neurotransmitters
Allows people to live a fairly normal life but drugs don't cure the disorder and if not take, symptoms reappear
Drugs can have serious side effects + could be argued that unbalances in neurotransmitters (e.g. low serotonin) in depressed people is the consequence rather than the cause of depression as the brain is a plastic organ which changes with the way we use it so it could be that the depressed thinking causes the low level of serotonin observed.