Cortical metabolite alterations in abstinent cocaine and cocaine/alcohol-dependent subjects: proton magnetic resonance spectroscopic imaging

Chronic abuse of cocaine or alcohol is associated with structural, neuropat hological and cognitive impairments that have been documented extensively. Little is known, however, about neurobiochemical changes in chronic substan ce abusers. We performed MRI and multi-slice brain proton magnetic resonanc e spectroscopic imaging (MRSI) to assess neuronal viability (via N-acetylas partate (NAA)) and white matter metabolite status tit 22 4-months-abstinent individuals dependent oz crack cocaine only and on both crack cocaine and alcohol. Compared to II non-dependent controls we found (1) significantly l ower NAA measures in the dorsolateral prefrontal cortex of the combined coc aine-dependent groups; (2) comparable spatial distribution and magnitude of these NAA effects for both cocaine-dependence groups; (3) higher choline-c ontaining metabolites in frontal white matter of individuals dependent on b oth cocaine and alcohol; (4) absence of brain atrophy in both abstinent coc aine-dependent samples; and (5) partial recovery from prefrontal cortical N AA loss, primarily with abstinence from alcohol. The MRSI findings suggest preferential neuronal damage to the frontal cortex of both cocaine-dependen t samples and gliosis in frontal white matter of individuals dependent on b oth alcohol and cocaine, conditions that persist for more than 4 months of abstinence.