Friday, December 30, 2011

Schizophrenics have too tightly wound DNA

Schizophrenia is described as a disease of the mind, and is often associated with people that have a split personality. However, it is actually a disease with many symptoms, and a split personality, despite movies such as Me Myself & Irene, is not one of them. In an effort to understand more of the biological mechanisms of schizophrenia, scientists from Scripps Research Institute have discovered that the structure of DNA of patients is quite different from that of healthy people. Large parts of the genetic code are too tightly wound, which renders the cellular machinery unable to read the genes that are present in these areas.

The researchers focussed on so-called epigenetic changes, which are inheritable characteristics that modify the DNA, by adding or removing certain molecules to the code. It differs from genetics because the actual genetic code remains unchanged. In schizophrenia, parts of the DNA have less acetyl groups attached to them, which results in tightening of the string of code on the histones, the latter being the structures that the DNA is wound on. Too tightly wounded parts of DNA were found in the brain cells of schizophrenics, and might explain some of the brain pathology we have previously found. Genetics were already found to play a large role: studies with identical twins have revealed that there are various genes in the schizophrenic brain that are less active. The study by the Scripps Research Institute reveals it may actually be epigenetic factors that are responsible for genetic causes of schizophrenia.
From right to left: strands of DNA get wound up on beads, called histones, compressing the structure. 
Schizophrenic brains
In schizophrenia, more than other diseases of the mind, we find several biological mechanisms that underly the disease. For example, patients are found to have an excess of the brain messenger dopamine. It is believed that factors during pregnancy play a large role in the development of schizophrenia, such as substance abuse by the mother. However, this can also cause the disease during life. The risk of developing schizophrenia can be inherited, but there are actually many other factors that play a role. Next to the aforementioned factors, there are a lot of hypotheses that aim to explain its biological foundation.

Schizophrenia has a wide variety of symptoms, and is actually quite a remarkable disease. Symptoms are divided between positive and negative. The positive symptoms include hallucinations, hearing voices, and basically all other things that these people 'add' to reality. Less well-known are the negative symptoms, which include lack of responsiveness, lack of social engagement or the inability to experience pleasure. Peculiar enough, some patients with negative symptoms can remain motionless for hours, which is described as catatonia. Taken together, it shows schizophrenics can experience a wide variety of symptoms, and not all of them are found in every patient.

It is important to understand the biology of schizophrenia, as the disease has a big impact on the life of patients. Their life expectancy is also much lower, and a subset of schizophrenics is suicidal. Because there are drugs that can reverse epigenetic changes, we may be able to improve treatment for patients with the findings from the Scripps Research Institute. Current therapies focus on ameliorating the symptoms, mainly the positive ones. There is no cure.
The most common misconception of schizophrenia. The picture actually displays a dissociative identity disorder.

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