David Baxter PhD
Late Founder
More Research Links Flu to Schizophrenia
Tuesday, November 27, 2007
The fever of influenza and the psychotic hallucinations of schizophrenia might seem to have no connection, but some doctors have long suspected that a correlation exists. Much of their initial suspicion stemmed from the observation that schizophrenia is more common for those born in winter, the season in which the flu spreads most virulently. This pattern is intriguing, but it is far from decisive proof. It is only recently that research is providing strong evidence of a link, and a clearer picture of how such a link operates.
The first concrete evidence of the flu-schizophrenia link came from prenatal serological blood samples obtained by Dr. Alan Brown. Dr. Brown had to wait decades until the children reached the age of schizophrenia vulnerability, but his patience paid off? he announced at a 2004 meeting of the APA that mothers with high levels of influenza antibodies had children that were three to seven times more likely to be schizophrenic.
Antibodies are regularly used by doctors to determine exposure to a virus, so at first Dr. Brown assumed that it was the virus that was damaging the fetus. However, a study published recently in the Journal of Neuroscience showed that it was the immune system response, not the virus itself, that corrupts the brain. When the mother?s immune system responds to a flu invasion, it sends the cytokine interleukin-6 to attack the attacker. When pregnant mice are injected with interleukin-6, their offspring suffer many of the symptoms associated with schizophrenia in humans. As mice have often proven accurate substitutes for humans in anti-psychotic medication trials, this study has probably pinned down the mechanism by which the flu interferes with brain development.
This is not the first invader tied to schizophrenia; back in June, we discussed evidence that the Epstein-Barr virus and the toxoplasma gondii parasite correlated with schizophrenia. While twin studies make plain that there is some genetic component to schizophrenia, there is now a convincing mass of research supporting the idea that infections can trigger this psychosis. The relative weights of genetic and infection risk factors remains to be determined. Also up in the air is the question of what practical steps to take if the flu does cause schizophrenia. Currently, the CDC recommends that all pregnant women get the flu shot. However, if it is the immune response that does the damage, then vaccines may bring more danger than protection. This requires careful consideration, not the panic that has spurred many parents to blame vaccinations for a variety of illnesses even when evidence fails to confirm their fears. Until the relative risks of vaccination and virus are fully evaluated, expectant mothers should take traditional precautions such as insisting that everyone wash his/her hands.
Tuesday, November 27, 2007
The fever of influenza and the psychotic hallucinations of schizophrenia might seem to have no connection, but some doctors have long suspected that a correlation exists. Much of their initial suspicion stemmed from the observation that schizophrenia is more common for those born in winter, the season in which the flu spreads most virulently. This pattern is intriguing, but it is far from decisive proof. It is only recently that research is providing strong evidence of a link, and a clearer picture of how such a link operates.
The first concrete evidence of the flu-schizophrenia link came from prenatal serological blood samples obtained by Dr. Alan Brown. Dr. Brown had to wait decades until the children reached the age of schizophrenia vulnerability, but his patience paid off? he announced at a 2004 meeting of the APA that mothers with high levels of influenza antibodies had children that were three to seven times more likely to be schizophrenic.
Antibodies are regularly used by doctors to determine exposure to a virus, so at first Dr. Brown assumed that it was the virus that was damaging the fetus. However, a study published recently in the Journal of Neuroscience showed that it was the immune system response, not the virus itself, that corrupts the brain. When the mother?s immune system responds to a flu invasion, it sends the cytokine interleukin-6 to attack the attacker. When pregnant mice are injected with interleukin-6, their offspring suffer many of the symptoms associated with schizophrenia in humans. As mice have often proven accurate substitutes for humans in anti-psychotic medication trials, this study has probably pinned down the mechanism by which the flu interferes with brain development.
This is not the first invader tied to schizophrenia; back in June, we discussed evidence that the Epstein-Barr virus and the toxoplasma gondii parasite correlated with schizophrenia. While twin studies make plain that there is some genetic component to schizophrenia, there is now a convincing mass of research supporting the idea that infections can trigger this psychosis. The relative weights of genetic and infection risk factors remains to be determined. Also up in the air is the question of what practical steps to take if the flu does cause schizophrenia. Currently, the CDC recommends that all pregnant women get the flu shot. However, if it is the immune response that does the damage, then vaccines may bring more danger than protection. This requires careful consideration, not the panic that has spurred many parents to blame vaccinations for a variety of illnesses even when evidence fails to confirm their fears. Until the relative risks of vaccination and virus are fully evaluated, expectant mothers should take traditional precautions such as insisting that everyone wash his/her hands.
