Is(poly-)substance use associated with impaired inhibitory control? A mega-analysis controlling for confounders

Many studieshave reportedthatheavysubstance useisassociatedwith impairedresponseinhibition.Studies typically focused on associations with a single substance, while polysubstance use is common. Further, most studiescomparedheavyuserswithlight/non-users,thoughsubstanceuseoccursalongacontinuum.Thecurrent mega-analysis accounted for these issues by aggregating individual data from 43 studies (3610 adult participants)thatusedtheGo/No-Go(GNG)orStop-signaltask(SST)toassessinhibitionamongmostly“recreational” substanceusers(i.e.,therateofsubstanceusedisorderswaslow).Mainandinteractioneffectsofsubstanceuse, demographics, and task-characteristics were entered in a linear mixed model. Contrary to many studies and reviewsinthefield,wefoundthatonlylifetimecannabisusewasassociatedwithimpairedresponseinhibitionin theSST.Aninteractioneffectwasalsoobserved:therelationshipbetweentobaccouseandresponseinhibition (intheSST)differedbetweencannabisusersandnon-users,withanegativeassociationbetweentobaccouseand inhibitioninthecannabisnon-users.Inaddition,participants’age,educationlevel,andsometaskcharacteristics influenced inhibition outcomes. Overall, we found limited support for impaired inhibition among substance userswhencontrollingfordemographicsandtask-characteristics.