The strong relationship between the two medical conditions suggest these diseases may share genetic, environmental or neurobiological causes.
"If you have epilepsy, be aware of mental health issues."
The first study in the world to investigate this relationship was recently conducted in Taiwan. There, researchers from the China Medical University Hospital used data from the Taiwan National Health Insurance database to identify 5,195 patients with schizophrenia and 11,527 patients with epilepsy, all diagnosed between 1999 and 2008.
Comparing the two patient groups and matching age and sex, researchers analyzed the risk of each group developing the other disease. Findings showed that the incidence of epilepsy was higher in the schizophrenia patient group (6.99 per 1,000) than in a control group of patients without schizophrenia (only 1.19 per 1,000).
For the patient group with epilepsy, the incidence of schizophrenia was 3.53 per 1,000, compared to 0.46 in the non-epilepsy control group. Incidences of schizophrenia was also slightly higher in men with epilepsy than in women with the disease.
Lead author I-Ching Chou, M.D., said that the results showed a strong bidirectional relation between schizophrenia and epilepsy. "This relationship may be due to common pathogenesis in these diseases such as genetic susceptibility and environmental factors, but further investigation of the pathological mechanisms are needed."
The findings were published in the journal Epilepsia in September 2011.