Toxoplasmosis linked to greater schizophrenia severity

By Mark Cowen, Senior medwireNews Reporter

Schizophrenia patients infected with Toxoplasma gondii have more severe symptomatology than those without the infection, researchers report.

The findings, published in Acta Psychiatrica Scandinavica, also suggest that schizophrenia patients infected with T. gondii have a poorer illness course than uninfected patients.

"The toxoplasmosis-associated differences in the course of schizophrenic illness may provide a rationale for the inclusion of anti-Toxoplasma antibodies screening programmes and more assertive preventative, educational and diagnostic measures," comment Lucie Bankovská Motlová (Prague Psychiatric Centre, Czech Republic) and team.

The researchers studied the symptom profiles, cognitive performance, and treatment response of 57 Toxoplasma-infected schizophrenia patients and 194 uninfected schizophrenia patients treated in the Prague Psychiatric Centre between 2000 and 2010.

They found that infected men and women had significantly higher mean positive symptom subscale scores on the Positive and Negative Symptom Scale (PANSS) than uninfected men and women, at 14.88 and 13.92 versus 12.98 and 12.07, respectively.

Infected men also scored significantly higher than uninfected men on the PANSS total (67.41 vs 62.90), negative (19.34 vs 17.85), reality distortion (8.34 vs 7.12), disorganization (8.75 vs 8.09), and cognitive (9.23 vs 8.32) subscale scores.

Concentrations of anti-Toxoplasma antibodies decreased with increasing duration of infection. And higher PANSS scores for positive, negative, and disorganized symptoms were associated with lower titres of anti-Toxoplasma antibodies in infected individuals.

This, say the researchers, suggests that "psychopathology deteriorates with duration of parasitic infection."

The team also found that infected patients remained in hospital for around 33 days longer than uninfected patients during their last admission.

Motlová et al conclude: "Latent toxoplasmosis in schizophrenia may lead to more severe positive psychopathology and perhaps less favourable course of schizophrenia."

They add: "We believe that the long-term effect of toxoplasmosis in schizophrenia needs a more careful investigation because it may result in higher risk of relapse, poorer treatment response, an insufficient adherence to treatment or poor psychosocial functioning."

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