The influence of methadone on cerebral gray matter and functional connectivity

Methadone maintenance treatment (MMT) is widely used for heroin use disorder. Although its curative effect is remarkable, there are problems associated with its use. While previous studies have found that methadone use may have certain effects on cerebral white matter, its effect on gray matter (GM) and its related neural networks is unclear. This study aimed to observe the effects of long-term methadone use on cerebral GM and the changes in related neural networks.

Patients receiving MMT treatment for heroin use disorder (N=50) were recruited. Longitudinal self-control was adopted, and the voxel-based morphometry (VBM) was used to compare the difference in cerebral GM volume before and after 1 year of methadone use, then we select the brain region where the GM volume changed as the region of interest (ROI), and use the DPARSF software for the whole brain function connection, and the differences in brain function connections before and after 1year MMT treatment were compared.

Our results demonstrated that, after 1 year of MMT, patients showed smaller GM volume in the bilateral insula, occipital lingual gyrus, right cingulate gyrus, middle temporal gyrus, left inferior parietal lobule, caudate nucleus, temporal, and occipital regions, and the resting neural network of the brain also changed.

We speculate that long-term methadone use can lead to damage to GM structure and adaptive changes in the neural network of patients with heroin use disorder, mainly involving emotional perception, spatial localization, working memory, and other related functions.