The presence of a gun in the home increases the risk of suicide by three to five times

A review of 467 studies also points out that, instead of alleviating feelings of fear and anxiety, weapons increase them, as well as exacerbating controlling behaviors and causing domestic violence.

By Luciana Constantino  |  Agência FAPESP – In addition to posing physical and life risks, access to firearms has an impact on mental health. It increases suicides, intensifies psychological fragility, and amplifies violence. This is the conclusion of a study published in the September issue of the scientific journal Harvard Review of Psychiatry.

The study was led by researchers from the Institute of Psychiatry at the University of São Paulo’s Medical School (FM-USP) in Brazil. The researchers conducted a systematic review of 467 studies from various countries published up to March 2023. Most of the studies – 81% (378) – were conducted in the United States; 6% were conducted in Western Europe; 4% in Australia; and 3% in Canada. The rest were conducted in other regions.

The analysis explored the links between access to firearms, aggressive behavior, substance use and abuse, social and domestic violence, and their influence on mental health. Three psychological mechanisms related to these factors were identified.

The first is that weapons facilitate impulsive acts in times of crisis or distress. Suicide was the main outcome, appearing in 284 studies (61% of the total). The analysis showed that the presence of a firearm in a home increases the risk of suicide three to fivefold, regardless of the individual’s previous mental health status. When firearms are stored safely, this risk decreases but remains high.

A second mechanism is that the weapon acts as a kind of “psychological amplifier,” exacerbating certain mental health conditions. Rather than alleviating feelings of fear and anxiety, the weapon exacerbates them, leading to aggression. Additionally, it exacerbates the symptoms of trauma in individuals exposed to armed violence, creating a feedback loop that intensifies suffering rather than alleviating it.

Finally, the weapon serves as a symbol that transforms power dynamics and perceptions of vulnerability. This exacerbates controlling behaviors and leads to cases of social and domestic violence.

“Understanding that everyone is susceptible to human frailties, the possibility of having highly lethal tools available in the hands of the general population, instead of increasing the sense of security and protection and improving the individual’s emotional regulation, ends up having the opposite effect, as we see in studies. It highlights emotional weaknesses, increases feelings of fear and aggression, and leads to an increase in cases of harassment and violence,” explains Rodolfo Furlan Damiano, a psychiatrist and the corresponding author of the article, to Agência FAPESP.

Damiano and Eurípedes Constantino Miguel Filho, a professor at the USP Medical School, coordinate the Program for Education, Research and Care in Treatment-Resistant Depression, Self-Injury, and Suicidality (Pro-DRAS). Damiano has the support of FAPESP through a postdoctoral fellowship for a project seeking to provide information on the effectiveness and feasibility of rapid interventions for suicide prevention.

Last year, Damiano coordinated another study that mapped risk and protective factors for suicidal behavior. The study showed that people with impulse control disorders (ICDs) are at risk (read more at agencia.fapesp.br/53522). 

Screening of studies

The review followed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline, a set of 27 items that systematizes the collection and extraction of data for this type of research.

The review began with a database of 3,930 articles from PubMed, Scopus, Web of Science, and PsycInfo. The screening protocol prioritized studies in criminology, public health, and sociology with direct outcomes and/or proven implications for psychological factors. This resulted in 467 articles addressing gun ownership, violence, policies, and their effects on mental health.

“The idea for this work arose from the link between suicide and firearms, but we realized that it could be something more comprehensive. When it comes to access to weapons, the discussion is always related to the issue of public safety. Our goal with the research wasn’t to deal with this sphere, but rather with mental health, which is an important and little-discussed issue,” Damiano explains.

In their conclusions, the scientists suggest adopting public policies that incorporate health-related scientific evidence.

“This review highlights the urgent need for comprehensive policies that address access to firearms, tackle the social determinants of the harm they cause, and promote mental health interventions. An integrated approach that considers these individual and social factors is essential to mitigate the complex psychological pathways through which they affect different populations,” the authors write in the article.

The situation in Brazil

Despite the small research sample size in Brazil, Damiano says the results are applicable to the country’s reality. “We’re dealing with mental health and the human impact, which can be extrapolated,” the psychiatrist says.

In Brazil, the purchase of firearms – both permitted and restricted caliber – is subject to a series of rules and requires authorization from federal agencies such as the Federal Police and the Army. In addition to being at least 25 years old, applicants must present a clean criminal record and prove their technical ability and psychological aptitude to handle firearms.

Despite the slowdown in growth since 2018, the number of registered firearms in Brazil increased by 3.2% between 2023 and 2024, reaching a total of 2,154,000 registrations in the National Firearms Registry System (SINARM), which is managed by the Federal Police. This information can be found in the 2025 Brazilian Public Security Yearbook. 

Damiano says he intends to continue the review work, focusing on laws that restrict access to firearms.

The article “The impact of firearm ownership, violence, and policies on mental health: a systematic scoping review” can be read at journals.lww.com/hrpjournal/abstract/2025/09000/the_impact_of_firearm_ownership,_violence,_and.1.