Neuropsychological functioning in methadone maintenance patients versus abstinent heroin abusers

Journal article


Research Areas

Publication Details

Author list: AntonioVerdejo, InmaculadaToribio, CarmenOrozco, Krista LeePuente, & MiguelPérez-García
Publisher: Elsevier: 12 months
Publication year: 2005
Volume number: 78
Issue number: 3
Start page: 283
End page: 288
Number of pages: 6
ISSN: 0376-8716
Languages: English-Great Britain (EN-GB)


Several studies have reported on neuropsychological status as an
important contributing variable in drug abuse rehabilitation outcomes.
However, few studies have dealt with cognitive impairment in methadone
maintenance patients (MMP), despite the fact that methadone is the most
frequently used opioid substitution treatment in European countries. The
objective of the present study is to contrast the neuropsychological
performance of MMP with that of abstinent heroin abusers (AHA).
Participants were matched with respect to age, education, pre-morbid IQ,
employment status and lifetime drug abuse, and they underwent a set of
tests aimed at assessing visuo-spatial attention, processing speed and
executive functions. Although processing speed and attention deficits
have previously been the focus of studies with MMP, executive functions
have not received a similar degree of attention. The purpose of
comparing matched MMP and AHA is two-fold: firstly, to test the
differential effects of current opioid consumption and past opioid abuse
on cognitive–executive performance and secondly, to assess the
potential consequences of opioid-related neuropsychological deficits.
Results showed a significantly slower performance by MMP on processing
speed, visuo-spatial attention, and cognitive flexibility tests (Five
Digit Test (FDT) parts 1 and 3; Oral Trails (OT) parts 1, 2;
Interference 2–1), and less accuracy in working memory and analogical
reasoning tests extracted from the Wechsler Adult Intelligence Scale
(WAIS III). Effect sizes for significant comparisons ranged from 0.67 to
1. These results seem to suggest that methadone consumption by itself
induces significant cognitive impairments that could compromise
drug-treatment outcomes in MMP.


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Last updated on 2019-13-08 at 00:15