Objective: The purpose of this work was to assess neuropsychological functioning of individuals in early abstinence from methamphetamine dependence and to test for cognitive change over the first month of abstinence.
Method: Methamphetamine-dependent subjects in very early abstinence from methamphetamine (4-9 days; n = 27) were compared with healthy comparison subjects (n = 28) on a test battery that evaluated five cognitive domains (attention/processing speed, learning/memory, working memory, timed executive functioning, and untimed executive functioning). A subsample of the methamphetamine-dependent subjects (n =18), who maintained abstinence for 1 month, as well as a subsample of the comparison subjects (n = 21), were retested.
Results: At the first assessment, the methamphetamine-dependent subjects showed significantly worse performance than the comparison group on a test of processing speed; they also performed 0.31 SDs worse than the control group on a global battery composite score (p < .05). After a month of abstinence, methamphetamine-dependent subjects demonstrated slightly more cognitive improvement than healthy control subjects on the entire cognitive battery, but this difference did not approach statistical significance (p = .33).
Conclusions: Our findings suggest that methamphetamine-dependent subjects do not show considerable cognitive gains in the first month of abstinence. A greater length of abstinence may be needed for cognitive improvement.