The digit-symbol substituion task (DSST) of the WAIS was given to
working (MW) and nonworking (MNW) patients on high-dose methadone
maintenance and to two comparison groups to assess the function of
attention in these patients. Mean DSST scores were significantly lower for
the MNW group than for the other three groups, which did not differ.
However, the scores for the MNW group were within the normal range. DSST
scores and lenght of methadon treatment (range: 11 months to 8 years) were
positively correlated, providing no evidence of deterioration with
increasing duration of treatment.