Neuroanatomy refers to the different activities and structures of the brain regions and tissue. This is often tested through MRI scans of normal people and comparing to those mentally ill. One example is schizophrenia where the ventricles appear enlarged and the amount of grey matter in the brain is reduced. It is however hard to differentiate between causation and effect, as not knowing which proceeds which can only lead to guess work in terms of causation. Another issue is not every mentally ill person has the same structural abnormalities, and where one schizophrenic shows marked differences to a normal person, another schizophrenic can show little to none.
Neurochemistry refers to the function and availability of neurotransmitters such as dopamine, GABA, serotonin and noradrenalin. Dependent on the area of the brain they occur in, each affect behaviour in a different want. During synaptic response these neurotransmitters are passed across the synapse from the axon terminal to the dendrite of another nerve. A lot of dysfunction of neurochemicals occurs during this response. For example in depression it is believed that a lack of available serotonin can cause the specific phenotype. This theory has been backed up by anti-depressants such as SSRI’s and MAOI’s which work to make serotonin more available in the synapse by preventing reuptake into the axon terminal. The drugs have shown to have be effective, therefore the theory must be partly correct. There are issues however, even though anti-depressants have a high success rate, compared to the placebo trials which where also very high, the actual success rate of the drugs alone is very little. They also question the actual theory of serotonin as the cause. The drugs are immediately effective in their function, however it can take months for them to show improved function in the person when in reality it should be immediate effect.
And finally genetics play a role in all of the above theories. Biological psychologists believe that every mental illness has a genetic component, from inheriting the chemical imbalance to structural abnormalities. This theory is researched by family, adoption and predominantly twin studies. By comparing the morbidity rate of DZ and MZ twins, psychologists can produce a concordance rate of the disease which roughly estimates the genetic probability of the disease occurring. This is a good method as it can quite clearly separate biological from environmental factors as MZ twins share 100% the same genes and both types of twins often share the same upbringing and environment. However there are many issues that lie in this method. Gene-environment interactions is when a persons genes directly influences their environment, epigenetics is where the environment actually changes the genotype and gene-environment correlations is where the genes are more likely to be found in certain environments. All of these issues cause problems in differentiating and separating what is genetics and what is environment. Sample sizes in these studies are often very small as twins with mental illness’ willing to be studied can be hard to find, especially when reared apart.
In conclusion there are four main basis of abnormality in the biological approach: infection, Neuroanatomy, neurochemistry and genetics. Due to the issues and uncertainty of these theories, I believe that until the neural code is better understood, looking at the biological model for answers is going to cause more problems than it is answers.
