Saturday, January 27, 2007

Toxoplasmosis is mood altering?

Recent reports in the popular press suggest that infection by Toxoplasma gondii (toxoplasmosis) may alter human behavior and cause schizophrenia. T. gondii is a common infection of domestic cats. Unfortunately, the full text of this science paper is not available for free. However, we can analyze in depth these findings from a comprehensive study of young children, comparing those who were infected congenitally with those who were not. This study was aimed at addressing understandable “parental concerns and anxiety”. In a prospective study, pregnant women and neonates were screened for toxoplasmosis between 1996 and 2000 in ten European centers. At 3 years of age, parents of children with and without congenital toxoplasmosis were surveyed about their child's development and behavior using a postal questionnaire. Parents of 178/223 (80%) infected, and 527/821 (64%) uninfected children responded. The researchers “found no evidence that impaired development or behavior were more common in infected children”. Well, that's certainly reassuring though it's not nearly as “newsworthy”.
Freeman K, Salt A, Prusa A, Malm G, Ferret N, Buffolano W, Schmidt D, Tan HK, Gilbert RE; European Multicentre Study on Congenital Toxoplasmosis. "Association between congenital toxoplasmosis and parent-reported developmental outcomes, concerns, and impairments, in 3 year old children." BMC Pediatr. 2005 Jul 13;5:23.

1 comment:

Reuel said...

One Step Removed?

These authors found a correlation between schizophrenia and the levels and types of antibodies to T. gondii in young adults suffering their first episode. Higher levels of antibodies and those types associated with more protracted exposure correlated with worse symptoms. This suggests that the course of the immune response, not the infection itself, might underlie the development of schizophrenia. However, less than half of the schizophrenia patients had detectable antibodies (16/38 or 42% of the schizophrenics; 3/27 or 11% of the controls), suggesting that the link is not that strong.