Experiencing risk factors — such as physical or sexual abuse, migration, cannabis consumption or problematic alcohol use — during teenage years may increase the chances of becoming a violently aggressive adult, a new study suggests.
The findings, published in the journal Molecular Psychiatry, suggested that children and adolescents who grow up with one or more of these environmental risk factors are likely to resort to violence, aggression and crime as adults, irrespective of an underlying mental illness.
"Our data support the concept of a disease-independent development of violent aggression in people exposed to multiple pre-adult environmental risk factors," said lead author Hannelore Ehrenreich from the Max Planck Institute of Experimental Medicine in Germany.
For the study, the researchers analysed data from six different study populations.
Overall, the data stemmed from more than 1500 people living with schizophrenia, as well as more than 550 members of the general population.
The researchers factored in aspects such as whether the person grew up in an at-risk area, namely if he or she was living in a big city or had migrated, experienced forms of physical or sexual abuse or used cannabis or engaged in problematic alcohol consumption before the age of 18 years.
As outcome measure, the researchers evaluated whether study participants had been convicted of violent crimes such as sexual assault, manslaughter, battery or murder.
In all groups, people who had experienced at least one of the high-risk factors had a marginally higher chance of becoming violently aggressive.
With every additional risk factor, this chance increased step-wise, reflected by a stair pattern throughout all six populations, the researcher said.
When all high-risk factors were considered together, a person with high risk load -- three or more of these risk factors -- was ten times more likely to become violently aggressive, the researchers added.