title: The relationship between the striatal dopamine transporter and novelty seeking and cognitive flexibility in opioid dependence.
abstract: Novelty seeking (NS) is a core personality trait that primes the susceptibility to drug addiction. Striatal dopamine activity contributes to cognitive flexibility, an important cognitive strategy to inhibit impulsivity and compulsive drug-seeking behavior. Evidence supports the association between dopamine and NS. Opioid-dependent patients show higher levels of NS, and repeated opioid exposure can cause cognitive deficits including poor cognitive flexibility and impaired impulse control. However, in opioid-dependent patients, the link between NS, striatal dopamine activity, and cognitive flexibility is still unclear. We recruited 22 opioid-dependent individuals and 30 age- and sex-matched healthy controls. Single-photon emission computed tomography with [99mTc]TRODAT-1 as a ligand was used to measure the striatal dopamine transporter (DAT) availability. The Trail Making Test (TMT) was performed to assess cognitive flexibility. Cloninger's Tridimensional Personality Questionnaire (TPQ) was used to measure NS. We found that in opioid-dependent patients, the striatal DAT availability was lower and negatively associated with TMT Part B÷Part A. Moreover, an inverted-U shape significantly matched the scores of NS as a function of the striatal DAT availability, with maximum NS potential in the midrange of the DAT availability. An extra sum-of-squares F test was conducted, indicating that a quadratic model fitted the association between the DAT and NS better than a linear model did. In brief, in opioid-dependent patients, the striatal DAT availability is nonlinearly linked to NS and linearly linked to cognitive flexibility. The role of the striatal DAT in the transition from controlled to compulsive opioid use warrants further research.
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Chih-Sung
authors.initials: CS
authors.lastname: Liang
authors.affiliation: Department of Psychiatry, Beitou Branch, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Pei-Shen
authors.initials: PS
authors.lastname: Ho
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Neurology, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Che-Hung
authors.initials: CH
authors.lastname: Yen
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Chun-Yen
authors.initials: CY
authors.lastname: Chen
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Shin-Chang
authors.initials: SC
authors.lastname: Kuo
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Taipei Branch, Buddhist Tzu Chi General Hospital, Taipei, Taiwan, ROC.
authors.forename: Chang-Chih
authors.initials: CC
authors.lastname: Huang
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Yi-Wei
authors.initials: YW
authors.lastname: Yeh
authors.affiliation: Department of anatomy and biology, National Defense Medical Center, Taipei, Taiwan, ROC.
authors.forename: Kuo-Hsing
authors.initials: KH
authors.lastname: Ma
authors.affiliation: Graduate Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan, ROC; Department of Psychiatry, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan, ROC. Electronic address: hsy@ndmctsgh.edu.tw.
authors.forename: San-Yuan
authors.initials: SY
authors.lastname: Huang
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000633:toxicity*; D003072:Cognition Disorders / Q000209:etiology*; D003342:Corpus Striatum / Q000000981:diagnostic imaging / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D005106:Exploratory Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009293:Opioid-Related Disorders / Q000150:complications* / Q000000981:diagnostic imaging / Q000473:pathology / Q000523:psychology; D015609:Organotechnetium Compounds / Q000378:metabolism; D010555:Personality Inventory; D012189:Retrospective Studies; D018709:Statistics, Nonparametric; D013624:Taiwan; D015899:Tomography, Emission-Computed, Single-Photon; D014326:Tropanes / Q000378:metabolism
chemical_list: D000701:Analgesics, Opioid; D050483:Dopamine Plasma Membrane Transport Proteins; D015609:Organotechnetium Compounds; D014326:Tropanes; C104196:technetium Tc 99m TRODAT-1
keywords: Cognitive flexibility; Dopamine transporter; Inverted-U-shape; Novelty seeking; Opioid-dependence; Striatum