Dietary supplements
There has been very little research examining the use of dietary supplements for ADHD. However, two meta-analyses have concluded that omega-3 supplementation is associated with modest ADHD symptom improvement for single disorder ADHD in children and adolescents [930, 931]. Moreover, another study has reported that omega-3 and omega-6 fatty acids have similar benefits to, and may improve the tolerability of, methylphenidate in single disorder ADHD [932]. In contrast, however, an RCT examining the role of omega-3 and omega-6 supplementation over 12 weeks in children with ADHD did not find any significant treatment effects on aggression, impulsiveness, depression, or anxiety symptoms relative to placebo [933]. Findings from these studies suggest that intervention length may moderate treatment effects, and that omega-3 and omega-6 supplements may require dosing durations of up to 6 months before any symptom benefits become evident [933]. While these findings have yet to be replicated among adults, and among people with co-occurring ADHD and AOD use, they point to potential avenues of future research.
Mindfulness
Mindfulness interventions for single disorder ADHD have been evaluated in three meta-analyses, which found reductions in ADHD and depressive symptoms, and improvements in executive functioning among children, adolescents, and adults, with larger effects for adults than children [934–936]. Some research suggests that, among adults, mindfulness exerts similar effects to other established treatment strategies (e.g., structured skills training [906]). However, this research is yet to be conducted among people with co-occurring ADHD and AOD use.