Accumulating evidence indicates concordant epigenetic dysregulation in the brain and peripheral blood leukocytes in schizophrenia. It has also been found that stressful and traumatic events may alter DNA methylation; however, such studies have not been performed in schizophrenia patients.

This study aimed at comparing LINE-1 methylation in first-episode schizophrenia (FES) patients and healthy control (HC) subjects with respect to the history of trauma.

We recruited 40 FES patients and 49 HC subjects matched for age, gender and body mass index (BMI). The early trauma self-report – short form (ETISR-SF) was administered to assess traumatic events. In addition to assessment of LINE-1 methylation, serum levels of homocysteine, folate and vitamin B12 were measured in all subjects.

There was no significant difference in LINE-1 methylation between FES patients and HC subjects. However, LINE-1 methylation was significantly lower in FES patients with positive history of trauma when compared with FES patients and HC subjects with negative history of trauma (58.08±3.27% vs. 61.28±4.12%, p = 0.022 and 58.08±3.27% vs. 61.12±4.73%, p = 0.038, respectively). There was no significant difference in LINE-1 methylation between FES patients and HC subjects with negative history of trauma. There was a negative correlation between total trauma score and LINE-1 methylation (r = −0.390, p = 0.012). After controlling for confounding variables (age, gender, treatment duration, pack-year index, metabolic parameters), LINE-1 methylation was associated with total trauma score (p = 0.011).

Traumatic events might be associated with lower global DNA methylation in FES patients.