Dorsolateral prefrontal cortex and basal ganglia alterations in cannabis consumers using proton MR spectroscopy

Cannabis use is widespread throughout the world and had been used for both medicinal and recreational purposes for centuries. Nevertheless little is known about the neurotoxicity of cannabis use. There is some evidence for both neurotoxic and neuroprotective properties from animal studies. We included 13 male cannabis users and 13 male comparism subjects in our study. The current cannabis consume was 0.7g cannabis/d, the cumulative dose of the last 3 months was 55g cannabis. The current use of other illegal drugs was excluded by a bedside test. THC hair concentrations were quantified for all participants via gas-chromatography-mass-spectrometry. A Multislice-Spectroscopic-Imaging (MSSI) was performed with a 1.5T MR scanner. 8 regions of interest with known high concentrations of cannabinoid receptors, were selected: basal ganglia (putamen and globus pallidus), thalamus, dorsolateral prefrontal cortex, frontal white matter, hippocampus, ventral tegmentum area, anterior cingulate, posterior cingulate. The main result was a significant reduction of the NAA/creatine and NAA/choline ratios in the dorsolateral prefrontal cortex of the cannabis users as compared with the control subjects. For semiquantitative NAA and Cr concentrations a loss was detected within putamen and thalamus in consumers. Data showed positiv correlations between THC dose and NAA/CR ratio in DLPFC. Thus it seems not plaussible to assume a pure neurotoxic or neuroprotective action of cannabinoids.