Metabolic abnormalities in lobar and subcortical brain regions of abstinent polysubstance users: magnetic resonance spectroscopic imaging

Abstract

Aims: The aim of the study was to explore neurometabolic and associated cognitive characteristics of patients with polysubstance use (PSU) in comparison with patients with predominant alcohol use using proton magnetic resonance spectroscopy.

Methods: Brain metabolite concentrations were examined in lobar and subcortical brain regions of three age-matched groups: 1-month-abstinent alcohol-dependent PSU, 1-month-abstinent individuals dependent on alcohol alone (ALC) and light drinking controls (CON). Neuropsychological testing assessed cognitive function.

Results: While CON and ALC had similar metabolite levels, persistent metabolic abnormalities (primarily higher myo-inositol) were present in temporal gray matter, cerebellar vermis and lenticular nuclei of PSU. Moreover, lower cortical gray matter concentration of the neuronal marker N-acetylaspartate within PSU correlated with higher cocaine (but not alcohol) use quantities and with a reduced cognitive processing speed.

Conclusions: These metabolite group differences reflect cellular/astroglial injury and/or dysfunction in alcohol-dependent PSU. Associations of other metabolite concentrations with neurocognitive performance suggest their functional relevance. The metabolic alterations in PSU may represent polydrug abuse biomarkers and/or potential targets for pharmacological and behavioral PSU-specific treatment.

Fig. 1.

Monthly cocaine consumption quantities in PSU vs. NAA concentration in frontal GM (FGM, left panel) and temporal GM (TGM, right panel). i.u. represents institutional units, for participants with both cocaine use and useful metabolite data. Regression fit and 95% confidence interval of the mean are indicated.