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NEW YORK (Reuters Health) - During childhood, a serious viral infection that attacks the central nervous system (CNS) appears to increase the risk of schizophrenia and certain psychoses later in life, research suggests.
The findings also indicate a specific association with certain viruses, including mumps virus and cytomegalovirus -- a member of the herpes family of viruses. Both of these pathogens are known to be adept at invading the brain.
"There are very few studies on this topic," Dr. Christina Dalman, from the Karolinska Institute in Stockholm, told Reuters Health. "Compared to former studies, our study is population-based and has a proper control group. Most important though, is that our study is much larger." This enabled the team to study childhood CNS infections, which are rare.
The study involved a national cohort of 1.2 million children who were born between 1973 and 1985. Included were 2435 children who were hospitalized for a bacterial CNS infection and 6550 who were hospitalized for a viral CNS infection, before the age of 13 years.
Overall, 2269 subjects were later diagnosed with a psychotic illness. "Among these, 23 individuals (including 8 with schizophrenia) were diagnosed with a CNS infection before the age of 12," the researchers report.
The risk ratio for psychotic illness later in life was 1.5 if a child had been exposed to a viral CNS infection. The risk ratio was found to be higher in women than in men. Bacterial CNS infection, by contrast, did not appear to increase the risk of psychotic illness.
Regarding schizophrenia in particular, viral CNS infection was associated with a risk ratio of 1.6. Once again, bacterial CNS infection did not influence the risk.
Further analysis showed that CNS infection with mumps virus or cytomegalovirus greatly increased the risk of psychotic illness with risk ratios of 2.7 and 16.6, respectively.
The researchers are now involved in a study looking at how infections during fetal and neonatal life influence the risk of psychotic illness.
SOURCE: American Journal of Psychiatry, January 2008.
