Altered small-world brain functional networks and duration of heroin use in male abstinent heroin-dependent individuals.

Although previous studies reported addiction-related alteration in resting-state brain connectivity, it is unclear whether these resting-state connectivity alterations were associated with chronic heroin use. In the current study, graph theory analysis (GTA) was applied to detect abnormal topological properties in heroin-dependent individuals. Several statistical parameters, such as degree (D), clustering coefficient (C) and shortest absolute path length (L), were included to test whether or not there was significant correlation between these parameters and the duration of heroin use. Our results demonstrated abnormal topological properties in several brain regions among our heroin-dependent subjects. Some of these regions are key areas of drug addiction-related circuits (control, reward, motivation/drive and memory), while others are involved in stress regulation. In addition, the duration of heroin use was positively correlated with the parameter D in the right parahippocampal gyrus, left putamen and bilateral cerebellum, but negatively correlated with the parameter L in the same regions. Our findings suggested that there is abnormal functional organization in heroin-dependent individuals and that the duration of heroin use is a critical factor leading to the altered brain connectivity.