title: Cognitive functioning in opioid-dependent patients treated with buprenorphine, methadone, and other psychoactive medications: stability and correlates.
abstract: BACKGROUND
  In many but not in all neuropsychological studies buprenorphine-treated opioid-dependent patients have shown fewer cognitive deficits than patients treated with methadone. In order to examine if hypothesized cognitive advantage of buprenorphine in relation to methadone is seen in clinical patients we did a neuropsychological follow-up study in unselected sample of buprenorphine- vs. methadone-treated patients.
  
  
  METHODS
  In part I of the study fourteen buprenorphine-treated and 12 methadone-treated patients were tested by cognitive tests within two months (T1), 6-9 months (T2), and 12-17 months (T3) from the start of opioid substitution treatment. Fourteen healthy controls were examined at similar intervals. Benzodiazepine and other psychoactive comedications were common among the patients. Test results were analyzed with repeated measures analysis of variance and planned contrasts. In part II of the study the patient sample was extended to include 36 patients at T2 and T3. Correlations between cognitive functioning and medication, substance abuse, or demographic variables were then analyzed.
  
  
  RESULTS
  In part I methadone patients were inferior to healthy controls tests in all tests measuring attention, working memory, or verbal memory. Buprenorphine patients were inferior to healthy controls in the first working memory task, the Paced Auditory Serial Addition Task and verbal memory. In the second working memory task, the Letter-Number Sequencing, their performance improved between T2 and T3. In part II only group membership (buprenorphine vs. methadone) correlated significantly with attention performance and improvement in the Letter-Number Sequencing. High frequency of substance abuse in the past month was associated with poor performance in the Letter-Number Sequencing.
  
  
  CONCLUSIONS
  The results underline the differences between non-randomized and randomized studies comparing cognitive performance in opioid substitution treated patients (fewer deficits in buprenorphine patients vs. no difference between buprenorphine and methadone patients, respectively). Possible reasons for this are discussed.
authors.affiliation: Department of Psychiatry, Helsinki University Central Hospital, Finland. pekka.rapeli@hus.fi
authors.forename: Pekka
authors.initials: P
authors.lastname: Rapeli
authors.forename: Carola
authors.initials: C
authors.lastname: Fabritius
authors.forename: Hely
authors.initials: H
authors.lastname: Kalska
authors.forename: Hannu
authors.initials: H
authors.lastname: Alho
mesh_terms: D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects; D002047:Buprenorphine / Q000008:administration & dosage* / Q000009:adverse effects; D003071:Cognition / Q000187:drug effects*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008691:Methadone / Q000008:administration & dosage* / Q000009:adverse effects; D009483:Neuropsychological Tests; D058850:Opiate Substitution Treatment / Q000009:adverse effects / Q000379:methods* / Q000523:psychology; D009293:Opioid-Related Disorders / Q000188:drug therapy* / Q000523:psychology*; D011597:Psychomotor Performance / Q000187:drug effects; D013223:Statistics as Topic / Q000379:methods
chemical_list: D000701:Analgesics, Opioid; D002047:Buprenorphine; D008691:Methadone