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Dopamine: Psychotic fire-starter?

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firemonkee57

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Joined
Mar 23, 2009
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8,224
The eye-catching title of the 2014 Paykel Lecture certainly lived up to its promise of a fascinating talk. Delivered by Dr Oliver Howes of the Institute of Psychiatry, Psychology and Neuroscience (IoPPN – King’s College London), the title made reference to an early paper on the dopamine hypothesis of schizophrenia, where dopamine was referred to as “the wind of the psychotic fire.” An eloquent review of the dopamine hypothesis followed, from the perspective of studies employing positron emission tomography (PET) and magnetic resonance imaging (MRI).

Dopamine is an important neurotransmitter, playing a crucial role in brain processes such as how we predict events and experience rewards. Its over-abundance in the brain has long been posited as a theory for the symptoms of psychosis seen in people with schizophrenia. Brain imaging techniques such as PET, which uses a radioactively labelled tracer, can help us obtain information about all aspects of the dopamine system. We can specifically study dopamine receptors, dopamine synthesis, its transportation or its release from neurons, and these methods have allowed scientists to pinpoint abnormalities in schizophrenia.

Using this technology, Dr. Howes and colleagues studied people with schizophrenia who had received very little treatment, and found that the abnormality of dopamine appears to be at the level of synthesis and release from brain cells, rather than at the receptor as was initially believed.

But this, Dr. Howes went on to explain, does not tell us whether schizophrenia is caused by an abnormality in dopamine regulation, or whether increased dopamine is a result of having schizophrenia. Therefore, his group decided to conduct research studies with a group of people who were at high risk of developing schizophrenia but do not yet show symptoms adequate for a diagnosis. These people are said to be in the prodromal, or sub-clinical, phase of schizophrenia. Whilst many go on to develop further symptoms, some remain stable at the sub-clinical phase and are able to function perfectly well. A prominent historical example of such a person, Dr. Howes explains, was Joan of Arc. Despite hearing voices (which she attributed to angels), she was able to lead the French army to victory over the British.

Thus, using the same PET imaging techniques, Dr Howes and his team found elevated dopamine synthesis in the striatum of people with sub-clinical symptoms, which appeared to be around halfway between controls and people diagnosed with schizophrenia. Further investigation found that this increase in dopamine was in fact specific to those who would go on to develop a full clinical syndrome of schizophrenia, while those with long term sub-clinical symptoms did not demonstrate any increase in dopamine synthesis.

Dopamine: Psychotic fire-starter? The Paykel Lecture 2014 - Department of Psychiatry
 
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letalis

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Dec 6, 2014
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68
I am disappointed psychiatry continues to chase unicorns.
 
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