Twenty-two studies were included in the review. The total number of participants included in the review was not stated. The number of participants in each study ranged from 40 to 1,011. Seven studies were randomised controlled trials (RCTs), two were cross-sectional, and thirteen were prospective or retrospective observational study designs. The 22 papers represent 9 cohorts and several papers that reported on the same cohort.
Few differences were observed for those with and without ASPD, receiving treatment for opioid dependence, with respect to retention, reduction in human immunodeficiency virus (HIV) risk behaviours and drug use. The results were also consistent across treatment modalities.
Two studies assessing psychotherapy found improvements in the Addiction Severity Index (ASI) score (p<0.05). One study found that participants with ASPD had improved scores in employment, as well as a reduction in drug use. A second study found that participants with ASPD alone showed little improvement in outcomes, whereas those with ASPD and depression experienced improvements in the composite scores for psychiatric, legal, drug use and employment sections of the ASI. One study assessing behavioural therapy found that participants with ASPD had a reduction in the ASI for drug use (p<0.05).
One study comparing DMI with amantadine and placebo found that participants with ASPD had lower retention, less cocaine-free urine samples and no response to amantadine DMI compared to those without ASPD (p<0.05). One study of participants with ASPD found no improvements in ASI scores for DMI, although DMI was effective in the group who did not have ASPD (p<0.05). A third study found no differences between participants with ASPD and those without for retention, positive opioid or cocaine urine samples, and abstinence from opioids or cocaine.
One study comparing CDTX or CMT with MM found that participants with ASPD were more likely to continue using benzodiazepines above the maintenance dose in the CMT group (p<0.05), but there were no differences in the CDTX group.
Two studies among methadone users with and without ASPD found no differences in respect to retention, methadone doses or needle-sharing. However, one study found significant reductions (p<0.001) in needle and risk behaviours among opiate users on MM treatment.
In one study of participants undergoing MM, all measures of antisociality were associated with noncompletion of the programme (<7 months; p<0.001). A further study assessing a major therapeutic programme found that those with co-morbid ASPD were more likely to drop out of treatment than those without a personality disorder (p=0.09).
In one study a greater number of ASPD symptoms predicted continued involvement in crime at 12 months (p<0.05). Another study found that ASPD was predictive of legal problems at the 6-month follow-up, although an earlier study by the same authors had found no differences in legal problems for those with ASPD when followed-up for 2.5 years, despite poorer psychosocial functioning. A further study found that those with ASPD had increased legal problems than those with no disorders (p<0.05).
There were generally no significant differences in the percentage of participants producing a positive opioid, cocaine or benzodiazepine urine sample between those with ASPD and those without, although one study found more urine samples testing positive for opioid and cocaine use in the ASPD group (p<0.05). One study also found significant reductions in drug use after 7 months’ follow-up for those with ASPD compared to those with other personality disorders or no personality disorder (p<0.05).