There exists a strong probability that other factors play a part in the potential causes of schizophrenia, being genetically related to someone with schizophrenia can significantly increase a person’s chances of developing it. Gottesman (1991) reviewed forty twin studies and found that with identical (MZ) twins there was a 48% chance of both being schizophrenic; with non-identical (DZ) twins that percentage had reduced but was still a significant 17%.
The same can be said of depression as it would appear that genetics equally plays a significant part in potential offspring developing endogenous depression or depression caused by internal factors, however, for both schizophrenia and depression other factors need to be considered such as neurological, behavioural, psychological and socio-cultural. (Coordination Group Publications 2009; Richard Gross 2010).
There are theories to suggest that abnormal brain structure caused by abnormal development could be the cause of schizophrenia. Johnstone et al (1976) compared the size of the ventricles in schizophrenics’ brains, they discovered that people with schizophrenia had enlarged ventricles which suggest that schizophrenia is linked to a loss of brain tissue, however non-schizophrenics can also have enlarged ventricles which is in direct opposition to Johnstones evidence. Buchsbaum (1990) carried out MRI scans on schizophrenics’ brains and found abnormalities in the prefrontal cortex, however these findings are inevitably correlational as they don’t display cause and effect; it may be that abnormal brain structure is a symptom of schizophrenia rather than a cause of it. (Coordination Group Publications 2009; Richard Gross 2010).
Behaviourists argue that schizophrenia is learnt through operant conditioning; someone may do something that gets a positive reaction or reward from others, this encourages the person to repeat the behaviour thus reinforcing it; token economies which use reinforcement to encourage supposed normal behaviours can help treat schizophrenia, suggesting that some of the behaviour could be learnt.
Behaviourists believe that depression develops when stressors such as bereavement or being made redundant lead to a lack of positive reinforcement, the attention that depressive behaviour then draws can then provide positive reinforcement, meaning the person learns to continue being depressed; it may also be influenced by learned helplessness, occurring when individuals learn not to try as they believe they will never succeed. Most biological and psychological research suggests that schizophrenia and depression are not merely learnt behaviours. (Coordination Group Publications 2009; Richard Gross 2010).
The social causation hypothesis states that people with low social status are more likely to suffer from either schizophrenia or depression, equally factors such as poverty and discrimination cause higher stress levels which are thought to be potential triggers. Harrison et al (2001) found that people who were born in deprived areas were more likely to develop schizophrenia, suggesting that factors such as poverty, unemployment and over-crowding may have an impact. (Coordination Group Publications 2009; Richard Gross 2010).
Freud claimed that schizophrenia is caused by over-whelming anxiety, it’s a defence mechanism involving regression into an earlier stage of development; Freud believed hallucinations are the ego’s attempt to restore contact with reality. Laing (1967) also argued that schizophrenics lose contact with reality as a way of coping with social pressure; Laing claimed that it was wrong to encourage schizophrenics to conform.
Freud also claimed that depression occurs when a child feels unloved by its parents and becomes angry, such anger then creates guilt so the anger is redirected towards the self; these feeling are eventually repressed but later return following a stressful and/or traumatic life event causing depression. Brown and Harris (1978) found that the women they interviewed were more likely to have depression if they experienced disrupted childhood attachments especially if their mother had died; unfortunately their isn’t sufficient research to support Freud’s theory, psychoanalysis isn’t an effective treatment for schizophrenia and is unfalsifiable in the treatment of depression. (Coordination Group Publications 2009; Richard Gross 2010).
It is possible that any numbers of factors in immeasurable quantities are potentially responsible for either schizophrenia or depression; any potential treatment is primarily dependent upon individual circumstances which in essence are almost impossible to pigeon hole or stereotype.
Coordination Group Publications 2009 AS ; A2 Psychology Exam Board AQA A Richard Gross 2010 Psychology: The Science of Mind and Behaviour Sixth Edition