Studies are beginning to address the aforementioned concerns by: (1) increasing sample sizes; (2) improving the measurement of SUD, particularly; (3) accounting for the genetic and environmental covariances across substances as well as between other comorbid outcomes; (4) increasing data collection of racially/ethnically diverse populations; and (4) accounting for ancestral diversity. The push to increase sample size in order to have appropriate power to detect significant associations for SUD is actively being addressed using consortia-based GWAS (e.g., Psychiatric Genetics Consortium- SUD working group (Agrawal, Edenberg, & Gelernter, 2016) as well as the study of GWAS data from large, nationally representative samples across several outcomes including SUD (e.g., UK Biobank—Littlejohns et al., 2017) and biological markers associated with SUD including neuroimaging (Mackey et al., 2016) may overcome current challenges.
