Geographic correlation of schizophrenia to ticks and tick-borne encephalitis.
Level 4 - case-series / case-control
Ecological correlation study comparing regional and national distributions without individual-level patient data
PubMed 7701281 · doi:10.1093/schbul/20.4.755
What was done
The author evaluated geographic distributions of schizophrenia, infectious diseases, Ixodid ticks, and tick-borne encephalitis across regions of the United States and several countries internationally to assess spatial correlation.
What was found
Schizophrenia prevalence in the United States was reported to correlate with geographic foci of Lyme disease and Ixodid tick vectors. Internationally, tick-borne encephalitis distribution concentrated in countries reported to have high rates of schizophrenia (including Croatia, Norway, Finland, Germany, and Ireland). The abstract provides no specific numerical values, correlation coefficients, or p-values.
Why it matters
The paper introduces a hypothesis linking perinatal or fetal exposure to tick-borne infectious agents or tick-borne encephalitis to geographic variation in schizophrenia onset.
Limits
The analysis relies on aggregate ecological-level correlations without individual patient data, risking ecological fallacy. The abstract reports no sample size, effect sizes, statistical metrics, or adjustments for confounding factors such as urbanization and diagnostic practices.
Cited by
- partial The geographic areas with the highest incidence of schizophrenia in the United States directly overlap with the highest incidence of Lyme disease.