Depression and Schizophrenia...the theories behind them

Depression and Schizophrenia are fairly well known medical mental disorders. Being a medical student myself, I knew about them before my lessons, but have now recently learnt the theories behind them; the theories differ, due to the fact that each one has been developed by a different person. They are as follows - environmental breeder hypothesis, Becks' cognitive theory of depression, the monoamine theory/hypothesis of depression and finally the dopamine theory/hypothesis of schizophrenia.

Lots of long words and a lack of explanation...Here is a breakdown of each one to make them more understandable and to see how they relate to the two mental disorders.




Becks' cognitive theory of depression:

This theory was developed by Aaron Beck in 1976; The theory suggests that negative thoughts generated by dysfunctional beliefs are the cause of depressive symptoms - the more negative thoughts one experiences, the more depressed the person becomes.

Schemas is a cognitive framework that helps organise information and process incoming information - Beck suggests 3 dysfunctional schemas are present in depressed people:

-I am defective/inadequate

-All my experiences result in failure

-My future is hopeless

These 3 schemas altogether form a negative triad, as can be seen below. 

Monoamine theory/hypothesis:

The Monoamine theory is one that was developed in terms of depression, developed by Teuting, Rosen and Hirschfeld in 1981 Neurotransmitters help the limbic system function in the brain and regulate drivers such as appetite and emotions. Suggestions for a cause for depression is an increased level of dopamine; dopamine being a neurotransmitter. Another suggestion is a lack of depletion of levels of serotonin and norepinephrine in the CNS (Central Nervous System). 

Dopamine theory/hypothesis:

The dopamine theory is one of the oldest and most established of the theories for schizophrenia. This particular hypothesis theorises that schizophrenia is caused by dopamine levels in the limbic system; a schizophrenic person produces more dopamine than usual and too much dopamine being active in the brain; As a result of this, this causes over-stimulation of the cells and this then causes symptoms of schizophrenia. To make it sound simpler, neurons use the neurotransmitter dopamine fire too often and can transmit too much information.

And this leads us onto the final theory which is the...

Environmental breeder hypothesis:

This final hypothesis is one that is also used for schizophrenia. Developed by Pedersen and Mortensen in 2001, the theory suggests that incidents of schizophrenia are more prevalent in lower classes and immigrant communities. The risk of schizophrenia in an inner city is more than twice of that in a rural area; the higher density living is associated with increased risk of mental illnesses. 

The breakdown and reasoning behind this theory can be seen below:

And that's it! 4 theories broken down in a way that hopefully made them easier to understand in terms of depression and schizophrenia.