Violence Exposure, Drug Use and HIV/AIDS Risk Taking Behaviors: The Role of Gender

DNA methylation and exposure to violence among African American young adult males

Exposure to violence (ETV) has been linked to epigenomics mechanisms such as DNA methylation (DNAm). We used epigenetic profiling of blood collected from 32 African American young adult males who lived in Washington DC to determine if changes in DNAm at CpG sites affiliated with nervous and immune system were associated with exposure to violence. Pathway analysis of differentially methylated regions comparing high and low ETV groups revealed an enrichment of gene sets annotated to nervous system and immune ontologies. Many of these genes are known to interact with each other which suggests DNAm alters gene function in the nervous and immune system in response to ETV. Using data from a unique age group, young African American adult males, we provide evidence that lifetime ETV could impact DNA methylation in genes impacted at Central Nervous System and Immune Function sites.

METHOD

Methylation analysis was performed on DNA collected from the blood of participants classified with either high or low lifetime ETV. Illumina®MethylationEPIC Beadchips (~850k CpG sites) were processed on the iScan System to examine whole-genome methylation differences. Differentially methylated CpG-sites between high (n ​= ​19) and low (n ​= ​13) groups were identified using linear regression with violence and substance abuse as model covariates. Gene ontology analysis was used to identify enrichment categories from probes annotated to the nearest gene.

RESULTS

A total of 595 probes (279 hypermethylated; 316 hypomethylated) annotated to 383 genes were considered differentially methylated in association with ETV. Males with high ETV showed elevated methylation in several signaling pathways but were most impacted at Central Nervous System and Immune Function affiliated sites. Eight candidate genes were identified that play important biological roles in stress response to violence with HDAC4 (10%), NR4A3 (11%), NR4A2 (12%), DSCAML1(12%), and ELAVL3 (13%) exhibiting higher levels in the low ETV group and DLGAP1 (10%), SHANK2 (10%), and NRG1(11%) having increased methylation in the high ETV group. These findings suggest that individuals subjected to high ETV may be at risk for poor health outcomes that have not been reported previously.

Exposure to personal and community violence and associated drug use outcomes in African American young adults

BACKGROUND

Exposure to violence (ETV) during one's life has been associated with increased risk for substance abuse. Adolescent ETV is also related to substance abuse into adulthood, and has been shown to have a cumulative effect. This study adds to the understanding of how ETV relates to a range of substance use outcomes by specifying how different types of violence affects substance use behaviors in African American young adults, and examines how this exposure is moderated by other life stressors, and health and social experiences.

METHOD

Factor analysis was conducted to identify unique types of ETV in 638 African American men and women ages 18-25. The resulting factors represent 1) childhood ETV and 2) community ETV as adults. These were regressed upon substance abuse outcomes.

RESULTS

78% of the respondents were exposed to some form of violence during their childhood. Lower childhood ETV were significantly associated with a lower risk of engaging in dangerous substance use behaviors. Adult experiences of community violence had more significant predictors of drug use than childhood ETV. Witnessing gunfire or an assault, witnessing or being a victim of sexual assault, and carrying a weapon were consistent risk factors for dangerous drug behaviors, although specific drug use behaviors differed across genders.

CONCLUSIONS

ETV served as an independent explanatory factor for specific drug use behaviors at different stages of life. Future research is needed to understand how these factors put respondents at risk for drug use behaviors or make them less likely to engage in dangerous use patterns.