Examining the Impact of Minimum Handgun Purchase Age and Background Check Legislation on Young Adult Suicide in the United States, 1991-2020.

Objectives. To examine the independent and joint effects of state legislation on minimum age for purchasing handguns and background checks on the suicide of young adults aged 18 to 20 years. Methods. We used negative binomial regressions with fixed effects for year and generalized estimating equations for state to estimate the effects of state legislation on annual counts of firearm, nonfirearm, and total young adult suicides in all 50 US states from 1991 to 2020. Results. Minimum age laws decreased the incidence rate of firearm suicide among young adults, an effect that was amplified in states with permit to purchase laws; there was no effect on the nonfirearm or total suicide rate. Permit to purchase laws significantly decreased the young adult firearm suicide incidence rate by 39% (incidence rate ratio [IRR] = 0.61; 95% confidence interval [CI] = 0.51, 0.74) and the overall suicide incidence rate by 14% (IRR = 0.86; 95% CI = 0.75, 0.99), with no effect on the nonfirearm suicide rate. Conclusions. Permit to purchase laws are a more promising avenue for reducing young adult suicides than are age-based restrictions. (Am J Public Health. 2024;114(8):805-813. https://doi.org/10.2105/AJPH.2024.307689).

A comparative framework for understanding and addressing interpersonal gun violence.

Gun violence, often characterized as a singular issue, is not one cohesive problem. Instead, it takes many forms resulting from the complex interplay of multiple factors. Outcomes of gun violence also vary significantly. They may be (a) physically non-injurious (a gun is brandished), (b) injurious but non-lethal, or (c) lethal. To understand and address gun violence effectively, it is essential to consider various risk factors for both non-lethal and lethal gun violence victimization, using a comprehensive, comparative framework. We present a novel comparative framework for better understanding gun violence, and for developing policy responses to this violence. We disaggregate gun violence into its various forms and propose a conceptualization of risk factors in discrete categories, each with important implications for policy intervention. While we emphasize the value of this framework for understanding and combatting interpersonal gun violence in America, the research and policy approaches discussed here should be equally applicable to other international contexts with gun violence as a serious public health issue as well.

Examining the Etiology of Asian American Suicide in the United States.

Research highlights racial and ethnic disparities in suicide, but Asian American suicide receives very little attention in the literature. This is the first comprehensive, large-scale, nationally representative study of completed suicide among Asian Americans in the United States. Descriptive and multilevel regression techniques compared the risk factors for completed suicide across 227,786 Asian American, White, African American, Hispanic, and American Indian suicide decedents from 2003 to 2019. Results indicated that Asian American suicide decedents were significantly less likely than their counterparts to have several risk factors for suicide. Asian Americans were less likely to be male, uneducated, and unmarried. Asian Americans were less likely to use alcohol and drugs, to have mental health problems, and to die by firearm, relative to other suicide methods. Asian Americans were less likely to have a history of prior suicide attempts, to have intimate partner problems, and to have criminal legal problems. Conversely, Asian Americans were more likely to reside in places with higher levels of concentrated disadvantage, residential instability, racial and ethnic heterogeneity, and population density. The results underscore the need for race-specific suicide prevention strategies that, for Asian Americans in particular, take into account cultural values and barriers to help-seeking behavior.

Disproportionate burden of violence: Explaining racial and ethnic disparities in potential years of life lost among homicide victims, suicide decedents, and homicide-suicide perpetrators.

Research indicates that the burden of violent death in the United States is disproportionate across racial and ethnic groups. Yet documented disparities in rates of violent death do not capture the full extent of this inequity. Recent studies examining race-specific rates of potential years of life lost-a summary measure of premature mortality-indicate that persons of color may die at younger ages than their counterparts, leading to increased trauma among surviving family members, friends, and communities. This study examines racial and ethnic disparities in potential years of life lost among people who died by homicide and suicide. We calculated potential years of life lost using life expectancy values specific to each racial and ethnic group, thereby isolating racial differences in potential years of life lost due to violence. Findings indicated that persons of color were disproportionately impacted by violence. Non-Hispanic African American homicide victims, suicide decedents, and homicide-suicide perpetrators died eleven or more years earlier than their non-Hispanic White counterparts. Similar disparities were observed for non-Hispanic Asian or Pacific Islander decedents. Less pronounced differences were observed for Hispanic and non-Hispanic American Indian or Alaska Native decedents. These racial and ethnic disparities were partly accounted for by a broad array of individual differences, incident characteristics, and contextual factors. The results suggest that homicide and suicide exact a high societal cost, and the burden of that cost is disproportionately high among persons of color.

Examining the Factors that Impact Suicide Following Heterosexual Intimate Partner Homicide: Social Context, Gender Dynamics, and Firearms.

Despite a wealth of research on intimate partner homicide, research on intimate partner homicide followed by suicide of the perpetrator is sparse. Existing studies on intimate partner homicide-suicide: tend to be descriptive, not keeping pace with quantitative advances in the epidemiological and social sciences; have yet to examine how context impacts intimate partner homicide-suicide; and are typically limited to male perpetrators, given small localized samples of female-perpetrated intimate partner (homicide and) homicide-suicide. This study uses data on 7584 heterosexual intimate partner homicide and homicide-suicide cases distributed across 2465 places and 42 U.S. states from the National Violent Death Reporting System (2003-2018) to examine the victim and perpetrator characteristics, relationship dynamics, situational factors, and contextual features that influence the likelihood of committing suicide following intimate partner homicide. Hierarchical logistic regression models indicate that victim characteristics that increase the vulnerability to victimization (alcohol and drug use, mental health problems, less than some college education) decrease the odds of committing suicide following intimate partner homicide. Similarly, situational (victim weapon usage, additional perpetrators) and contextual (concentrated disadvantage, residential instability) risk factors decrease the odds of committing suicide following intimate partner homicide. Conversely, impairment of the perpetrator (alcohol use, mental health problems) and a more intimate victim-perpetrator relationship (spousal relationship, caregiver) increases the odds of homicide-suicide. Additionally, results indicate that firearms play an integral part in homicide-suicide as well as in decreasing the gender gap in homicide-suicide. The findings suggest that the internalization of guilt by perpetrators of intimate partner homicide may play a key role in subsequent suicide. Practically, limiting firearm exposure will not only reduce the lethality of intimate partner violence, but will decrease the odds of perpetrator suicide following intimate partner homicide. This is particularly true for female-perpetrated homicide-suicide, which is unlikely to occur without a firearm.

A Multivariate Comparison of Family, Felony, and Public Mass Murders in the United States.

The mass murderer is known by a variety of names in both public and academic spheres, from the family annihilator to the active shooter, from the workplace avenger to the rampage school shooter. Although most researchers acknowledge that the phenomenon is heterogeneous, mass killing has defied classification, and currently no consensus typology exists. Most previous efforts at developing a classification scheme have focused on sorting these multicides into three broad groups, namely, family, felony, and public mass killings, exclusively relying on qualitative methods and case-study analysis to do so. The present study employs a multivariate approach to examine differences among types in victim, offender, and incident characteristics on the population of all mass murders in the United States from 2006 to 2016.

The relation between state gun laws and the incidence and severity of mass public shootings in the United States, 1976-2018.

OBJECTIVE: In this study, we analyzed the relationship between state firearm laws and the incidence and severity (i.e., number of victims) of mass public shootings in the United States during the period 1976-2018. HYPOTHESES: We hypothesized that states requiring permits to purchase firearms would have a lower incidence of mass public shootings than states not requiring permits. We also hypothesized that states banning large-capacity ammunition magazines would experience a lower number of victims in mass public shootings that did occur than states without bans. METHOD: We developed a panel of annual, state-specific data on firearm laws and mass public shooting events and victim counts. We used a generalized estimating equations logistic regression to examine the relationship between eight state firearm laws and the likelihood of a mass public shooting. We then used a zero-inflated negative binomial model to assess the relationship between these laws and the number of fatalities and nonfatal injuries in these incidents. RESULTS: State laws requiring a permit to purchase a firearm were associated with 60% lower odds of a mass public shooting occurring (95% confidence interval [CI: -32%, -76%]). Large-capacity magazine bans were associated with 38% fewer fatalities (95% CI [-12%, -57%]) and 77% fewer nonfatal injuries (95% CI [-43%, -91%]) when a mass shooting occurred. CONCLUSION: Laws requiring permits to purchase a gun are associated with a lower incidence of mass public shootings, and bans on large capacity magazines are associated with fewer fatalities and nonfatal injuries when such events do occur. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Overexpression of human NR2B receptor subunit in LMAN causes stuttering and song sequence changes in adult zebra finches.

Zebra finches (Taeniopygia guttata) learn to produce songs in a manner reminiscent of spoken language development in humans. One candidate gene implicated in influencing learning is the N-methyl-D-aspartate (NMDA) subtype 2B glutamate receptor (NR2B). Consistent with this idea, NR2B levels are high in the song learning nucleus LMAN (lateral magnocellular nucleus of the anterior nidopallium) during juvenile vocal learning, and decreases to low levels in adults after learning is complete and the song becomes more stereotyped. To test for the role of NR2B in generating song plasticity, we manipulated NR2B expression in LMAN of adult male zebra finches by increasing its protein levels to those found in juvenile birds, using a lentivirus containing the full-length coding sequence of the human NR2B subunit. We found that increased NR2B expression in adult LMAN induced increases in song sequence diversity and slower song tempo more similar to juvenile songs, but also increased syllable repetitions similar to stuttering. We did not observe these effects in control birds with overexpression of NR2B outside of LMAN or with the green fluorescent protein (GFP) in LMAN. Our results suggest that low NR2B subunit expression in adult LMAN is important in conserving features of stereotyped adult courtship song.

Core and Shell Song Systems Unique to the Parrot Brain.

The ability to imitate complex sounds is rare, and among birds has been found only in parrots, songbirds, and hummingbirds. Parrots exhibit the most advanced vocal mimicry among non-human animals. A few studies have noted differences in connectivity, brain position and shape in the vocal learning systems of parrots relative to songbirds and hummingbirds. However, only one parrot species, the budgerigar, has been examined and no differences in the presence of song system structures were found with other avian vocal learners. Motivated by questions of whether there are important differences in the vocal systems of parrots relative to other vocal learners, we used specialized constitutive gene expression, singing-driven gene expression, and neural connectivity tracing experiments to further characterize the song system of budgerigars and/or other parrots. We found that the parrot brain uniquely contains a song system within a song system. The parrot "core" song system is similar to the song systems of songbirds and hummingbirds, whereas the "shell" song system is unique to parrots. The core with only rudimentary shell regions were found in the New Zealand kea, representing one of the only living species at a basal divergence with all other parrots, implying that parrots evolved vocal learning systems at least 29 million years ago. Relative size differences in the core and shell regions occur among species, which we suggest could be related to species differences in vocal and cognitive abilities.