Altered functional connectivity of the nucleus accumbens subdivisions in amphetamine-type stimulant abusers: a resting-state fMRI study.

BACKGROUND: The growing abuse of amphetamine-type stimulants leads to new challenges to human health. A possible addiction mechanism has been proposed by altered functional architecture of the nucleus accumbens (NAc) during resting state. NAc contains different subdivisions and they may play different roles in addiction. The aim of the present study was to examine whether there are common or distinct patterns of functional connectivity of the NAc subdivisions in amphetamine-type stimulant abusers (ATSAs). METHODS: The present study recruited 17 male ATSAs and 22 healthy male controls. All the subjects underwent resting-state functional magnetic resonance imaging (fMRI) with their eyes closed. The NAc was divided into core-like and shell-like subdivisions. We used seed-based resting-state functional connectivity (RSFC) analyses to identify differences in brain functional architecture between ATSAs and healthy controls (HCs). RESULTS: ATSAs had lower positive RSFCs with all of the NAc subdivisions over the left orbital part of superior frontal gyrus and higher positive RSFCs with the NAc subdivisions over the left opercular part of inferior frontal gyrus than HCs, which indicates common abnormalities across the NAc subdivisions in ATSAs. In addition, the RSFCs between the NAc subdivisions and the left orbital part of superior frontal gyrus were negatively correlated with the addiction severity in ATSAs. CONCLUSION: These results provide evidence that there are common RSFC patterns of the NAc subdivisions in ATSAs. The abnormality indicated by disrupted functional connectivity between the NAc subdivisions and prefrontal cortex suggests abnormal interaction between the rewarding process and cognitive control in ATSAs. Our results shed insight on the neurobiological mechanisms of ATSA and suggest potential novel therapeutic targets for treatment and intervention of ATSAs.

Demographic and Clinical Features of Chinese Heroin Users Who Switch from Non-injection to Injection.

BACKGROUND: Injection drug users (IDUs) are at high-risk for acquiring human immunodeficiency virus, hepatitis C virus, and other infections, and delaying the switch from non-injection drug use to injection to drug use could reduce the spread of these infections. OBJECTIVES: To estimate the incidence of switching from non-injected heroin use (usually smoking or "chasing") to injection and to investigate the risk factors for this change. METHODS: We reviewed the socio-demographic and clinical data of 7305 heroin-dependent patients treated at a detoxification clinic of a university-affiliated psychiatric hospital in China from January 2000 to February 2009. RESULTS: Within 1 year, the majority of non-injection drug users (NIDUs) transitioned to IDUs (59.4% within 6 months and 76.7% within 12 months). Multiple logistic regression analysis showed that marital status, years of education, employment status, age at onset of heroin use, duration of drug abuse, and initial dose were associated with the switch from NIDU to IDU. Being married (B = -0.410, OR = 0.664), being employed (B = -0.243, OR = 0.784), and older age at onset (B = -0.040, OR = 0.961) were protective factors. More education (B = 0.120, OR = 1.128), longer duration of drug abuse (B = 0.010, OR = 1.010), and a higher dose at initial drug use (B = 0.234, OR = 1.264) were risk factors. CONCLUSIONS/IMPORTANCE: The study has identified several risk factors for the switch to injection among heroin users. Understanding these factors can help design new approaches to more specifically target high-risk populations and high-risk behaviors to delay or prevent the transition to injection.