An interesting case of epidemiology

Certain bugs and beasties cause effects in the bodies that they infect. Could this extend to mental behaviour and could a common micro-organism be at the root of a common disease? The Times Online has this story which might go a long way to explain the increase of schizophrenia:

Could mental illness be infectious?
Incidences of chlamydia found in patients suffering from schizophrenia may reveal a link between viruses and mental disorders.

Chlamydia is already known to cause considerable human misery. Not only is one strain of the micro-organism responsible for Britain�s "epidemic" of sexually transmitted disease, but another variant can cause a serious respiratory-tract infection similar to Sars.

Now comes the surprising finding by a German research team that chlamydia may be linked with schizophrenia. Dr Rudolf Wank, an immunologist at the Ludwig-Maximilians-University in Munich, has reported recently that schizophrenic patients are much more likely to be infected with one or more variants of chlamydia. More importantly, he found that targeting the bug with specially treated immune cells improved the patients� symptoms dramatically.

About 40 per cent of the 75 patients he studied were infected with chlamydia, compared with 6 per cent in the control group (ie, people who did not have schizophrenia). As Dr Wank explains: "Chlamydia comes in three varieties, two of which can cause a flu-like respiratory infection or pneumonia, while the third causes the sexually transmitted disease. The patients were much more likely to have one or more of these." The team also found that the risk of developing schizophrenia rose dramatically for patients with a certain group of immune system genes.

"Kurt" had been on antipsychotic medication for more than 20 years; he was aggressive, his speech incoherent and he was unable to work. In a report published in the journal Medical Hypotheses, Dr Wank described how, after identification of the strain of chlamydia infecting him and treatment with "treated" immune cells, within a few weeks Kurt�s aggression had disappeared and his speech had improved.

The idea that an infection might cause mental illness has a long history � it is well known, for instance, that certain conditions can have a psychological effect. Hepatitis B may cause depression and the microbes causing syphilis and Aids are linked with dementia.

Fascinating!