Suicide, Alcohol Intoxication, and Age Among Whites and American Indians/Alaskan Natives

Genetic factors associated with suicidal behaviors and alcohol use disorders in an American Indian population

American Indians (AI) demonstrate the highest rates of both suicidal behaviors (SB) and alcohol use disorders (AUD) among all ethnic groups in the US. Rates of suicide and AUD vary substantially between tribal groups and across different geographical regions, underscoring a need to delineate more specific risk and resilience factors. Using data from over 740 AI living within eight contiguous reservations, we assessed genetic risk factors for SB by investigating: (1) possible genetic overlap with AUD, and (2) impacts of rare and low-frequency genomic variants. Suicidal behaviors included lifetime history of suicidal thoughts and acts, including verified suicide deaths, scored using a ranking variable for the SB phenotype (range 0-4). We identified five loci significantly associated with SB and AUD, two of which are intergenic and three intronic on genes AACSP1, ANK1, and FBXO11. Nonsynonymous rare and low-frequency mutations in four genes including SERPINF1 (PEDF), ZNF30, CD34, and SLC5A9, and non-intronic rare and low-frequency mutations in genes OPRD1, HSD17B3 and one lincRNA were significantly associated with SB. One identified pathway related to hypoxia-inducible factor (HIF) regulation, whose 83 nonsynonymous rare and low-frequency variants on 10 genes were significantly linked to SB as well. Four additional genes, and two pathways related to vasopressin-regulated water metabolism and cellular hexose transport, also were strongly associated with SB. This study represents the first investigation of genetic factors for SB in an American Indian population that has high risk for suicide. Our study suggests that bivariate association analysis between comorbid disorders can increase statistical power; and rare and low-frequency variant analysis in a high-risk population enabled by whole-genome sequencing has the potential to identify novel genetic factors. Although such findings may be population specific, rare functional mutations relating to PEDF and HIF regulation align with past reports and suggest a biological mechanism for suicide risk and a potential therapeutic target for intervention.

Comorbidity of anxiety/affective, conduct/antisocial, attention deficit, and alcohol use disorders with suicidal behaviors in an American Indian community sample of adults and adolescents

AIMS

To study the associations of anxiety/affective disorders, conduct/antisocial disorders (ASPD/CD), attention deficit disorders (ADHD), and alcohol use disorders (AUD) with suicidal behaviors in an American Indian (AI) community sample of adolescents and adults.

METHODS

Participants were AI (360 adolescents, 925 adults) recruited from reservations who were assessed with the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA).

RESULTS

Among AI adults (mean age = 33 years), 17% percent reported lifetime experiences of suicidal thoughts (ideation and/or plans) and 14% reported suicidal acts (including either a suicide attempt history or verified death by suicide; n = 19 deaths). Among AI adolescents (mean age = 15 years), 20% experienced suicidal thoughts and 9% experienced suicidal acts (including 3 deaths). In logistic regression analyses, suicidal thoughts were significantly associated with lifetime diagnoses of affective disorder, CD and ADHD in adolescents, and with anxiety disorder, affective disorder, and ASPD/CD in adults. Suicidal acts were associated with affective disorder, ADHD, and alcohol drinking in adolescents and with anxiety disorder, ASPD/CD and AUD in adults. The number of comorbid disorders greatly increased the risk of both suicidal thoughts and acts among both adolescents and adults.

CONCLUSIONS

In addition to affective disorders, both ADHD and CD in adolescents, and ASPD in adults, demonstrated an association with suicidal thoughts. Alcohol use by adolescents and AUD among adults also were associated with suicidal attempts in this AI sample. These findings suggest need for additional research and potential integration of alcohol in screening and intervention programs focused on the prevention of suicide among AI.

Causal Inference with Case-Only Studies in Injury Epidemiology Research

Purpose of Review

We review the application and limitations of two implementations of the "case-only design" in injury epidemiology with example analyses of Fatality Analysis Reporting System data.

Recent Findings

The term "case-only design" covers a variety of epidemiologic designs; here, two implementations of the design are reviewed: (1) studies to uncover etiological heterogeneity and (2) studies to measure exposure effect modification. These two designs produce results that require different interpretations and rely upon different assumptions. The key assumption of case-only designs for exposure effect modification, the more commonly used of the two designs, does not commonly hold for injuries and so results from studies using this design cannot be interpreted. Case-only designs to identify etiological heterogeneity in injury risk are interpretable but only when the case-series is conceptualized as arising from an underlying cohort.

Summary

The results of studies using case-only designs are commonly misinterpreted in the injury literature.

Trends and disparities in American Indian/Alaska Native unintentional injury mortality from 1999 to 2016

INTRODUCTION

Alcohol and drug use are significant problems in the US, and American Indian/Alaska Native (AI/AN) communities and individuals are known to be among the most affected. This study evaluates disparities in unintentional injury mortality causes since 1999.

METHODS

Analyses in 2020 of unintentional injury mortality rate disparities between AI/ANs and white population over the 1999-2016 period with attention to motor vehicle crashes, alcohol poisoning, drug poisoning and all other cause types. Rates in each of the 10 states with the largest AI/AN populations were also investigated to account for geographical concentration.

RESULTS

Motor vehicle mortality rates declined for both AI/AN and white groups, but a large racial disparity was maintained. Conversely, poisoning mortality rates rose substantially in both groups, with a jump in rates in 2007 due to a coding change, resulting in a large disparity that was maintained through 2016. Comparison of alcohol and drug poisonings showed that the AI/AN alcohol poisoning rate was about eight times the white rate, whereas drug poisoning rates were similar. For 'all other' unintentional injuries, the highest rates were seen for AI/AN men, with rates generally rising over the study period. State-specific analyses found substantial variation in AI/AN rates, with few or no disparities in New York and Texas.

CONCLUSIONS

Results indicate substantial and persisting disparities in unintentional injury mortality, with especially large differences in alcohol poisoning. The absence of disparities in New York and Texas suggest the importance of situational factors.

Delta Event-Related Oscillations Are Related to a History of Extreme Binge Drinking in Adolescence and Lifetime Suicide Risk

Alcohol exposure typically begins in adolescence, and heavy binge drinking is associated with health risk behaviors. Event-related oscillations (EROs) may represent sensitive biomarkers or endophenotypes for early alcohol exposure as well as other risk behaviors such as suicidal thoughts and actions. In this study, young adults (age 18-30 years) of American Indian (AI) (n = 479) and Mexican American (MA) (n = 705) ancestry were clinically assessed, and EROs were generated to happy, sad and neutral faces. Extreme adolescent binge drinking (10+ drinks) was common (20%) in this population of AI/MA and associated with a significantly increased risk of a lifetime history of suicidal acts (SA, suicide attempts, deaths) but not suicidal thoughts (ST, ideation, plans). ST were reported among MA participants, whereas SA were more common among AI young adults. Extreme adolescent binge drinking was also associated with errors in detection of sad and neutral faces, increases in delta ERO energy, and decreases in phase locking (PL), particularly in parietal areas. A lifetime history of ST was associated with increases in delta ERO energy and PL, whereas SA were associated with decreases in both. These studies suggest that ERO measures may represent important potential biomarkers of adolescent extreme binge drinking and risk for suicidal behaviors.