1- Biochemical explanation of mental illness
To think/feel/act on a decision, the brain cells must transmit electrical impulses around our brains
At the end of each brain cell there is a synapse (gap) leading to the next cell
Neurotransmitters (chemicals) regulate different mental processes, mental illness symptoms can be the result of abnormal neurotransmitter levels
1- Depression = monoamine hypothesis
A group of neurotransmitters called monoamines release serotonin, noradrenaline and dopamine
Depression lowers the mood and disrupts activity levels, resulting in less active patients
Dopamine regulates mood, noradrenaline affects activity levels, while serotonin controls activity of those 2
A reduction in serotonin = failure of regulating dopamine and noradrenaline
2- Schizophrenia = dopamine hypothesis
High levels of dopamine in lower brain = symptoms of schizophrenia, e.g. hallucinations or hearing voices
Low levels of dopamine in pre-frontal cortex = apathy and incoherent thoughts/speech
2- Genetic explanations of mental illness
Total genetic makeup = genotype
Genes = sections of DNA that contain information for physical structures such as brain and chemicals
Genes have influence on psychological characteristics
Mental illness is unlikely a result of just genes, however some mental illnesses are more influenced by genes than others
1- Genetic vulnerability to depression
Strongest predictor of depression is stressful events, but some are more resilient to stress than others and that may be down to genes
Serotonin transporter gene produces serotonin
3 forms of the gene, in length of strands = long/long, long/short and short/short
Short long = inefficient serotonin production, more likely to get depression
2- Genetic vulnerability to schizophrenia
Schizophrenia runs in families but is not necessarily genetic, it could be situational
Schizophrenia co-varies with genetic similarity to family members who also have it, because there is a strong link between closer genetics and risk of developing schizophrenia
Number of genetic variations make us more vulnerable = polygenetic
Different combinations of factors lead to similar symptoms = aetiologically heterogeneous
3- Brain abnormality
Certain structures in our brains may develop with different sizes or shapes, or lower and higher levels of electrical activity in different regions
Particular areas of the brain malfunction during mental disorders, but it's unclear whether that's due to the abnormal neurotransmitter levels or if it's a separate phenomenon
1- Brain abnormality in depression
Frontal lobe volume in depressed patients = smaller
Frontal lobes in depression patients don't draw the blood flow in the brain normally, (hyperfusion) and this can be fixed with ECT
2- Brain abnormality in schizophrenia
In schizophrenia, the left hemisphere of the brain doesn't function normally, there are problems with the left brain which anti-psychotic drugs can correct
Loss of motivation, because the ventral striatum is functioning abnormally
Lower activation levels in superior temporal gyrus and the anterior cingulate gryus which result in hallucinations sometimes