Substance addictions and suicidal thoughts and behaviors: Evidence from a multi-wave epidemiological study

Substance addiction (SA) is a complex condition that can have a wide range of negative effects on an individual's physical, psychological, social, and occupational well-being. SA is associated to several mental health conditions, including major depressive disorder, bipolar disorder, borderline personality disorder, and dysthymia. One of the most severe consequences of SA is increased risk for suicide thoughts and behaviors (STB). The aim of this study was to define the differential associations between self-reported addiction to eleven substances and STB, namely suicide ideation, planning and attempt. The study is based on the National Survey on Drug Use and Health (NSDUH) data spanning from 2008 to 2020. The total sample, representative of the American population, is composed of more than 500 000 adult individuals (53.55% female), with a prevalence of people ranging between 18 and 25 years old (39.73%). We performed a series of logistic regressions in order to observe which substances were significantly related to each STB with at least a small effect size (d ≥ .20) through at least 8 years. The selected substances were alcohol, pain relievers, marijuana and cocaine for ideation and planning, and only alcohol, pain relievers and marijuana for suicide attempt. We prepared four predictor models: a socio-demographic one, a selected substances addiction one, one with all the non-selected substances and one with all the substances. We performed a ROC analysis for each year, model and STB. Finally, we averaged the ROC areas through the years and compared the models for each suicidal thought and behavior. The results confirmed the hypothesis: there is a differential association between addiction to different substances and STBs.