Brain perfusion in polysubstance users: Relationship to substance and tobacco use, cognition, and self-regulation

• We compared polysubstance-dependent to alcohol-dependent individuals on perfusion.
• Perfusion in polysubstance users was between that of the alcohol and control groups.
• Perfusion was significantly lower only in the alcohol group compared with controls.
• Greater drinking and smoking severity was associated with lower perfusion.
• Lower perfusion had cognitive ramifications and related to higher impulsivity.

BackgroundBrain perfusion is altered in both alcohol dependence and stimulant dependence. Although most substance users also abuse/depend on alcohol concurrently (polysubstance users; PSU), rigorous perfusion research in PSU is limited. Also, the relationships of perfusion abnormalities with cognition, impulsivity, or decision making are not well known.MethodsArterial spin labeling MRI and neuropsychological measures assessed perfusion levels and neurocognition in 20 alcohol-dependent individuals with comorbid-stimulant dependence (PSU), 26 individuals dependent on alcohol only (ALC), and 31 light/non-drinking controls (LD). The patient groups included smokers and non-smokers.ResultsALC had lower perfusion than LD in subcortical and cortical brain regions including the brain reward/executive oversight system (BREOS). Contrary to our hypothesis, regional perfusion was generally not lower in PSU than ALC. However, smoking PSU had lower perfusion than smoking ALC in several regions, including BREOS. Lower BREOS perfusion related to greater drinking severity in smoking substance users and to greater smoking severity in smoking ALC. Lower regional perfusion in ALC and PSU correlated with worse performance in different cognitive domains; smoking status affected perfusion–cognition relationships in ALC only. Lower BREOS perfusion in both substance using groups related to higher impulsivity.ConclusionAlthough regional perfusion was not decreased in PSU as a group, the combination of cigarette smoking and polysubstance use is strongly related to hypoperfusion in important cortical and subcortical regions. As lower perfusion relates to greater smoking severity, worse cognition and higher impulsivity, smoking cessation is warranted for treatment-seeking PSU and ALC.