Background: Inattention is a deficit related to instilling abstinence from methamphetamine (MA) dependence. This study aimed to determine whether ibudilast (IB; 50mg bid) improves attentional abilities compared to placebo during early abstinence from MA dependence.
Methods: Attention was assessed in 11 MA-dependent non-treatment seeking participants in a phase IB safety-interaction trial. The Conners' Continuous Performance Test-II (CPT-II), a measure of sustained attention and response inhibition, was administered at baseline and on day 22, 48h post a MA challenge under placebo (P; n=6) or IB 50mg bid (n=5). Group differences were compared using Mann-Whitney U Tests. Groups were similar at baseline in premorbid intellectual functioning, attention deficit hyperactivity symptom scores, impulsivity ratings, and education level, but differed in age. Demographically corrected T-scores for CPT-II performances were utilized.
Results: Although no group differences in sustained attention existed at baseline, at follow-up, the IB group (Mdn=44.4) showed reduced variability in response times compared with the P group (Mdn=69.9), U=0.00, z=-2.74, p=.006, r=.83. The IB group (Mdn=45.8) also gave fewer perseverative responses than the P group (Mdn=67.0), U=2.00, z=-2.50, p=.01, r=.75. No other significant differences were observed.
Conclusions: Findings suggest that IB may have a protective effect on sustained attention during early abstinence from MA dependence. This may guide thinking about mechanism of action should IB demonstrate efficacy as a treatment for MA dependence.
Keywords: CPT-II; Conners' Continuous Performance Test; Ibudilast; Methamphetamine dependence; Sustained attention.
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