Morphological brain alterations and morphological brain network disorganizations in heroin and methamphetamine abstinent patients

Heroin and methamphetamine are the two common types of drugs abused, which poses significant health risks. However, the neural mechanisms underlying the effects of drug addiction on human brain are unclear. In this study, we collected T1-weighted magnetic resonance imaging data from 26 heroin abstinent (HA) patients, 24 methamphetamine abstinent (MA) patients and 32 healthy controls. Four surface-based morphological features including cortical thickness (CT), fractal dimension (FD), gyrification index (GI), and sulcal depth (SD) were calculated, and further used to construct the morphological brain networks. We observed the common CT reductions of the right TE 1.0 and TE 1.2 and SD reductions of the right intermediate lateral area 20 for HA and MA patients, HA-specific CT reductions in the left area 2, and the MA-specific GI reductions in the left medial area 6 and right dorsomedial parietooccipital sulcus. For the morphological brain networks, HA patients exhibited the global disorganizations (higher shortest path length) in CT-based networks, whereas MA patients showed the disrupted nodal efficiency of the left medial area 38 in CT-based networks, the right caudal area 7 in GI-based networks, and the right inferior occipital gyrus in SD-based networks. Furthermore, the altered SD of HA patients and disrupted nodal efficiency of MA patients were associated with drug abuse-related clinical variables. Our findings suggest the morphological index-dependent effects of drug addiction on human brain morphology, and indicate the differential neural mechanism underlying heroin and methamphetamine abuses which attack the global and local information transfer of morphological brain networks, respectively.