Background: Suicidal behavior is a common phenomenon in those diagnosed with schizophrenia (SCZ). Studies have shown that around 5% of patients diagnosed with SCZ will die by suicide. In this study we aim to determine the association between methylation-based aging and the presence of lifetime suicide attempt.
Methods: We recruited 124 individuals with schizophrenia spectrum disorders from the Centre for Addiction and Mental Health in Toronto. The diagnosis was ascertained using the SCID-5 structured interview and venous blood was collected for genome wide methylation analysis. DNA Methylation was quantified using the Illumina Infinium HumanMethylation450 BeadChip array. Lifetime suicide attempt was determined through the Columbia Suicide Severity Rating Scale.
Results: Of the 124 participants, 47 were found to have had at least one suicide attempt lifetime. Epigenetic aging analysis was completed using R-4.2.1 (64-bit) and the Horvath Methylation Age Calculator. A significant difference between chorological age and epigenetic age for five clocks (Telomeric Length, Horvath DNAm Age, Hannum DNAm Age, Horvath Skin & Blood and PhenoAge) was determined within both suicide attempters and non-suicide attempters (p<0.0001). No significant difference in epigenetic aging was determined between suicide attempters and non-suicide attempters.
Discussion: This study is one of the first to investigate epigenetic age dysregulation in individuals with suicide attempt in schizophrenia. The results of our analysis revealed a non-significant difference in epigenetic age acceleration (EAA) between attempters and non-attempters (p>0.05). Future studies exploring EAA in the context of suicide risk should consider the stratification of participants by sex, as well as the confounding effect of medications on DNA methylation.