title: Response inhibition and psychomotor speed during methadone maintenance: impact of treatment duration, dose, and sleep deprivation.
abstract: BACKGROUND
  In opiate-dependent individuals, abstinence results in deficits in cognitive functioning, which may be exacerbated by medication-associated sleep disruption.
  
  
  METHODS
  To assess cognitive function and the influence of sleep deprivation (SD), 14 healthy control (HC) and 22 methadone maintained (MM) participants completed the continuous performance task (CPT) after a baseline night, a night of total SD, and two recovery sleep nights. The digit symbol substitution task (DSST) was administered at bedtime and in the morning. Secondary analyses separated MM participants into short- (< 12 months; n=8) and long-term (≥ 12 months; n=14) treatment duration groups, and into low- (< 80 mg; n=9) and high-dose (≥ 80 mg; n=13) groups.
  
  
  RESULTS
  Linear mixed model ANOVAs revealed that there was no effect of SD. Across all days MM participants had more errors of omission, fewer correct responses, and slower reaction times (RTs) on the CPT, and fewer accurate substitutions on the evening and morning DSST. Short-term MM participants exhibited slower RTs on the CPT, and fewer correct substitutions on the evening DSST compared to long-term MM participants. Low-dose MM participants had slower RTs on the CPT than HCs and high-dose MM participants.
  
  
  CONCLUSIONS
  These data demonstrate that methadone-maintained individuals exhibit poorer performance on tasks of psychomotor speed and selective attention/impulsivity, but with longer-term treatment, performance appears to return toward control levels. Furthermore, while one day of SD was enough to alter subjective reports of sleep quality, cognitive function may be more resilient.
authors.affiliation: Behavioral Psychopharmacology Research Lab, McLean Hospital, 115 Mill Street, Belmont, MA 02478, USA. bbracken@mclean.harvard.edu
authors.forename: B K
authors.initials: BK
authors.lastname: Bracken
authors.forename: G H
authors.initials: GH
authors.lastname: Trksak
authors.forename: D M
authors.initials: DM
authors.lastname: Penetar
authors.forename: W L
authors.initials: WL
authors.lastname: Tartarini
authors.forename: M A
authors.initials: MA
authors.lastname: Maywalt
authors.forename: C M
authors.initials: CM
authors.lastname: Dorsey
authors.forename: S E
authors.initials: SE
authors.lastname: Lukas
mesh_terms: D000328:Adult; D000339:Affect / Q000187:drug effects; D000704:Analysis of Variance; D001923:Brain Chemistry / Q000187:drug effects; D003071:Cognition / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004734:Energy Metabolism / Q000187:drug effects; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D008691:Methadone / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D009294:Narcotics / Q000008:administration & dosage / Q000009:adverse effects* / Q000627:therapeutic use; D058850:Opiate Substitution Treatment / Q000009:adverse effects* / Q000523:psychology*; D009293:Opioid-Related Disorders / Q000523:psychology* / Q000534:rehabilitation*; D011597:Psychomotor Performance / Q000187:drug effects*; D011930:Reaction Time / Q000502:physiology; D012892:Sleep Deprivation / Q000139:chemically induced* / Q000523:psychology*; D012894:Sleep Stages / Q000187:drug effects; D013997:Time Factors
chemical_list: D009294:Narcotics; D008691:Methadone