Abstract: Objective To estimate the influence of long and short-term addiction on the response inhibition function of heroin addicts. Methods 40 heroin addicts, divided into short-term group (ST group, 1-5 years, 19 participants) and long-term group (LT group,6-25 years, 21 participants), participated in our study while 40 healthy controls were matched. Stop signal task (included GO trials and NOGO trials) was used to investigate the response inhibition ability for these three groups. Results In GO trails, the reaction time of ST group[(1134±104)ms] and LT group[(1224±27)ms] were slower than controls [(1005±180)ms, P<0.05], and LT group was rather slower than ST group (P<0.05). In NOGO trails, significant differences were detected between controls[(92.5%±16.9%,83.5%±18.3%,64.3%±23.6%)] and long-term heroin addicts[(92.7%±16.7%,84.0%±18.3%,64.4%±23.4%)] when Stimulus Onset Asynchrony (SOAs) were 400, 600 and 800ms (P<0.05). Conclusions Heroin addiction may damage the response inhibition ability of addicts, and the longer they abuse, more seriously the deficits is.

Key words: heroin addiction, response inhibition, duration, Stop Signal Task