List psychological factors associated with risk of violence (not diagnoses)

The evidence shows that hostility, impulsivity, and substance use are the best-supported psychological risk factors for violence, but the retrieval is thin on direct comparisons to non-violent populations.

The strongest evidence comes from a 2021 study of 303 Hong Kong delinquent youth, which found that changes in impulsivity and low self-esteem directly mediated reductions in delinquent behavior after a cognitive-behavioral intervention [1]. A 1999 experiment on 8 men showed that high-trait hostility combined with low serotonin (via tryptophan depletion) produced measurable increases in laboratory aggression [2]. A 2018 review of fathers who had perpetrated domestic violence identified hostility and over-reactivity as the best-supported mechanisms, with substance use and depression as plausible but less-studied contributors [4].

A 2020 case series of 74 inpatients with amphetamine-related psychosis found that agitation and aggression were the dominant behavioral disturbances, with 53% showing aggression toward others and 66% destroying property [3]. A 2011 longitudinal study of 702 urban African Americans found that frequent adolescent drinking (20+ times by age 16) predicted a roughly 2-fold higher odds of violent arrest in adulthood, even after adjusting for other risk factors [5].

The retrieval does not include studies comparing violent to non-violent people on these traits using a true untreated control group. The evidence is mostly from clinical or delinquent populations, not from general community samples. The studies that exist are small or use self-reported outcomes.

My call: hostility, impulsivity, and substance use are the psychological factors with the strongest evidence linking them to violence risk, but the evidence base is narrower than it should be. Confidence: moderate.