title: Neuropsychological performance of methadone-maintained opiate users.
abstract: Methadone maintenance treatment (MMT) has been used to treat opiate dependence since the mid-1960s. Previous studies have investigated the effects of methadone on cognitive function however the findings have been inconsistent. Some report a complete absence of deficits while others report different types of cognitive impairment. Our research aimed to investigate the effects of MMT on cognitive function by comparing the performance of patients currently enrolled in MMT (n=32) with opiate-dependent subjects (n=17) and healthy control subjects (n=25) on a computerised neuropsychological test battery. Both the patients undertaking MMT and the opiate users showed less efficient interaction between visual searching and manually connecting digits and letters during the Switching of Attention Task than the healthy control subjects (F(2,64)=3.25, p=0.05), which indicates deficits in information processing. Nevertheless, the performance of the MMT group was similar to that of healthy control subjects in all other tasks, in contrast to the group of opiate users who performed poorly when compared to healthy control subjects during tests of attention (mean difference (MD)=2.8, 95% confidence interval (CI) (0.9-4.7), p=0.001) and executive function (MD=5.9, 95% CI (1.3-10.5), p=0.007). These findings suggest that cognitive function in patients undertaking MMT is improved compared to those dependent on illicit opiates.
authors.affiliation: School of Pharmacy, The University of Auckland, Auckland, New Zealand Centre for Brain Research, The University of Auckland, Auckland, New Zealand gwang@aut.ac.nz.
authors.forename: Grace Y
authors.initials: GY
authors.lastname: Wang
authors.affiliation: Department of Psychological Medicine, The University of Auckland, Auckland, New Zealand.
authors.forename: Trecia A
authors.initials: TA
authors.lastname: Wouldes
authors.affiliation: Department of Psychological Medicine, The University of Auckland, Auckland, New Zealand.
authors.forename: Rob
authors.initials: R
authors.lastname: Kydd
authors.affiliation: School of Pharmacy, The University of Auckland, Auckland, New Zealand.
authors.forename: Maree
authors.initials: M
authors.lastname: Jensen
authors.affiliation: School of Pharmacy, The University of Auckland, Auckland, New Zealand Centre for Brain Research, The University of Auckland, Auckland, New Zealand.
authors.forename: Bruce R
authors.initials: BR
authors.lastname: Russell
mesh_terms: D000293:Adolescent; D000328:Adult; D001288:Attention / Q000187:drug effects; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000139:chemically induced / Q000150:complications / Q000523:psychology*; D055030:Drug Users / Q000523:psychology; D056344:Executive Function / Q000187:drug effects; D005260:Female; D064368:Healthy Volunteers / Q000523:psychology; D006801:Humans; D008297:Male; D008691:Methadone / Q000009:adverse effects* / Q000627:therapeutic use; D008875:Middle Aged; D009483:Neuropsychological Tests; D058850:Opiate Substitution Treatment / Q000009:adverse effects*; D009293:Opioid-Related Disorders / Q000150:complications / Q000188:drug therapy / Q000523:psychology*; D055815:Young Adult
chemical_list: D008691:Methadone
keywords: Methadone maintenance; cognitive impairment; neuropsychological function; opiates