Extended findings of brain metabolite normalization in MA-dependent subjects across sustained abstinence: A proton MRS study

Abstract

Objective The goal of the present study was to extend our previous findings on long-term methamphetamine (MA) use and drug abstinence on brain metabolite levels in an expanded group of MA-dependent individuals. Methods Seventeen MA abusers with sustained drug abstinence (1–5 years), 30 MA abusers with short-term drug abstinence (1–6 months) and 24 non-substance using controls were studied using MR spectroscopy (MRS). MRS measures of NAA/Cr, Cho/Cr and Cho/NAA were obtained in the anterior cingulate cortex (ACC) and in the primary visual cortex (PVC). Results ACC-Cho/NAA values were abnormally high in the short-term abstinent group compared to controls [ F(1,52) = 18.76, p < 0.0001]. No differences were observed between controls and the long-term abstinent group [ F(1,39) = 0.97, p = 0.97]. New evidence of lower ACC-NAA/Cr levels were observed in the short-term abstinent MA abusers compared to controls [ F(1,52) = 23.05, p < 0.0001] and long-term abstinent MA abusers [ F(1,45) = 7.06, p = 0.01]. No differences were observed between long-term abstinent MA abusers and controls [ F(1,39) = 0.48, p = 0.49]. Conclusions The new findings of relative NAA/Cr normalization across periods of abstinence suggest that adaptive changes following cessation of MA abuse may be broader than initially thought. These changes may contribute to some degree of normalization of neuronal function in the ACC.