title: Explicit and implicit heroin-related cognitions and heroin use among patients receiving methadone maintenance treatment.
abstract: BACKGROUND
  Craving is an important issue in substance use disorder. To achieve a better understanding of the cognitive processing systems of craving, the cognitive processes of craving have been considered as two distinct processes. One system, based on rule-based inferences and named explicit cognition, is more conscious and effortful. The other system, based on prior learned association and named implicit cognition, is unconscious and effortless. How explicit and implicit cognitions are associated with heroin use in patients with methadone maintenance treatment (MMT) is not clear. This study aimed to explore the relationship between explicit and implicit cognition and heroin use in patients undergoing MMT.
  
  
  METHODS
  This study recruited one-hundred forty intravenous heroin users. The participants were invited to provide social-demographic data, the severity of substance dependence and explicit cognition with regard to heroin. Then, participants completed a computerized test to assess implicit cognition with regards to heroin.
  
  
  RESULTS
  This study found that explicit and implicit heroin-related cognitions were associated with the frequency of heroin use. There was an interaction effect between implicit and explicit cognition on the frequency of heroin use. This study also found that higher explicit heroin-related cognition was a risk factor for continuing heroin use.
  
  
  CONCLUSIONS
  Both explicit and implicit cognitions were associated with the frequency of heroin use in patients undergoing MMT, but only explicit cognition was associated with whether patients could stop using heroin during MMT. Therefore, the status of heroin use in patients undergoing MMT may be related to different cognitive processes.
authors.affiliation: Department of Psychiatry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Psychiatry, Faculty of Medicine and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Peng-Wei
authors.initials: PW
authors.lastname: Wang
authors.affiliation: Department of Psychiatry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Psychiatry, Faculty of Medicine and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Huang-Chi
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Departments of Addiction Science, Kai-Suan Psychiatric Hospital, Kaohsiung, Taiwan.
authors.forename: Hung-Chi
authors.initials: HC
authors.lastname: Wu
authors.affiliation: Departments of Addiction Science, Kai-Suan Psychiatric Hospital, Kaohsiung, Taiwan.
authors.forename: Chih-Yao
authors.initials: CY
authors.lastname: Hsu
authors.affiliation: Departments of Addiction Science, Kai-Suan Psychiatric Hospital, Kaohsiung, Taiwan.
authors.forename: Kuan-Sheng
authors.initials: KS
authors.lastname: Chung
authors.affiliation: Department of Psychiatry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Psychiatry, Faculty of Medicine and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan; Department of Psychiatry, Kaohsiung Municipal Hsiao-Kang Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan.
authors.forename: Chih-Hung
authors.initials: CH
authors.lastname: Ko
authors.affiliation: Department of Psychiatry, Kaohsiung Medical University Hospital, Kaohsiung, Taiwan; Department of Psychiatry, Faculty of Medicine and Graduate Institute of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung, Taiwan. Electronic address: chfaye@cc.kmu.edu.tw.
authors.forename: Cheng-Fang
authors.initials: CF
authors.lastname: Yen
mesh_terms: D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D003071:Cognition / Q000187:drug effects*; D005260:Female; D003932:Heroin / Q000494:pharmacology*; D006556:Heroin Dependence / Q000523:psychology* / Q000534:rehabilitation*; D006801:Humans; D008297:Male; D008691:Methadone / Q000627:therapeutic use*; D008875:Middle Aged; D009294:Narcotics / Q000494:pharmacology*; D009483:Neuropsychological Tests; D058850:Opiate Substitution Treatment / Q000523:psychology*; D011569:Psychiatric Status Rating Scales; D012307:Risk Factors; D012727:Sex Characteristics
chemical_list: D009294:Narcotics; D003932:Heroin; D008691:Methadone