This article is more than 5 years old. Information may no longer be current.
Link between academic achievement, drug abuse may be causal
Click Here to Manage Email Alerts
Two different methodological approaches — instrumental variable and co-relative analysis —implemented in a large sample of Swedish participants followed for an average of 19 years, indicated a causal connection between academic achievement assessed at age 16 years and drug abuse.
“If poor [academic achievement] contributes causally to risk of [drug abuse], then interventions that improve [academic achievement] should reduce [drug abuse] risk,” Kenneth S. Kendler, MD, from the Virginia Institute for Psychiatric and Behavioral Genetics, Virginia Commonwealth University, and colleagues wrote.
“A range of individual and school-based interventions for children and adolescents that have shown an impact on [academic achievement] also resulted in lower drug use,” they continued. “However, nearly all of these studies examined only substance use and follow-ups were typically short, making it difficult to confidently conclude from the current literature whether improving [academic achievement] will have a long-term influence on risk of [drug abuse].”
To better understand the association between adolescent academic achievement and drug abuse risk, researchers used instrumental variable (ie, month of birth) and co-relative analysis designs to assess nationwide data from Swedish-born individuals. The investigators conducted co-relative analyses in 263,222 pairs of cousins, 154,295 full siblings and 1,623 monozygotic twins discordant for academic achievement, then fit the raw results to a genetic model. Exposures included academic achievement assessed at 16 years of age for instrumental variable analyses and estimated discordance in academic achievement in pairs of monozygotic twins for co-relative analyses.
This instrumental variable analysis included 934,462 participants followed for 15 to 20 years. The two methods produced evidence that a substantial proportion of the observed relationship between low academic achievement and subsequent drug abuse risk could be causal, estimating that an increase of 1 standard deviation of academic achievement at 16 years of age should decrease long-term drug abuse risk by about 45%. Lower achievement had a significant link to risk for subsequent drug abuse (HR per SD = 2.33; 95% CI, 2.3-2.35).
Analysis revealed that earlier month of birth was linked to a linear effect on academic achievement. After controlling for academic achievement, the researcher found that month of birth had no link with risk for drug abuse. Furthermore, after applying the genetic model to the results of co-relative analyses, the academic achievement-drug abuse relationship in monozygotic twins discordant for academic achievement estimated an HR of 1.79 (95% CI, 1.64-1.92).
“Consistent with intervention studies, most of which had much shorter follow-ups and softer outcomes (eg, substance use), these results suggest that programs that improve [academic achievement] in adolescence should result in meaningful reductions in long-term [drug abuse] risk,” the authors wrote. “Such interventions may target individual students with academic services or may be comprehensive interventions that change school policies, organization, or climate to provide a more positive learning environment, thereby increasing the student-school emotional bond.” – by Savannah Demko
Disclosure: The authors report no relevant financial disclosures.