Verbal working memory deficits in abstinent heroin abusers.
BACKGROUND
A prevailing belief is that opioids tend not to impair cognitive performance in opioid-dependent users. However, the impact of heroin abuse on verbal memory, especially on working memory, is not well studied and the results available are inconsistent.


OBJECTIVE
This study was carried out to test the hypothesis that abstinent heroin abusers have intact working memory capacity.


METHODS
N-back task and backward digit span task were used to measure the verbal working memory capacity in 28 abstinent heroin abusers and 25 controls matched for age, education level and gender. Forward digit span task was used as a control task to measure short-term memory capacity.


RESULTS
Compared with the control subjects, heroin abusers showed normal backward/forward digit spans but significant performance impairment in the n-back task.


CONCLUSIONS
Abstinent heroin abusers have intact short-term memory capacity but impaired verbal working memory capacity.
Guangdong Key Laboratory of Medical Molecular Imaging, The First Affiliated Hospital, Medical College of Shantou University, Shantou, Guangdong, China.
Zhao-Xin
ZX
Wang
Guangdong Key Laboratory of Medical Molecular Imaging, The First Affiliated Hospital, Medical College of Shantou University, Shantou, Guangdong, China.
Zhuang-Wei
ZW
Xiao
Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui, China.
Da-Ren
DR
Zhang
Guangdong Key Laboratory of Medical Molecular Imaging, The First Affiliated Hospital, Medical College of Shantou University, Shantou, Guangdong, China.
Chun-Yu
CY
Liang
Department of Psychology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
John X
JX
Zhang