Objective Heroin dependent individuals appear to have significant deficits in attention which can be assessed using digit span forward (DSF) or the continuous performance test (CPT). The current meta-analysis examined differences between DSF and CPT results in studies of heroin dependent participants. Data selection Two researchers independently searched nine databases (e.g., PsycINFO, Pubmed, ProceedingsFirst), extracted required data, and calculated effect sizes. Inclusion criteria identified studies that had (a) compared heroin-dependent groups to healthy controls and (b) matched groups on either age, education, or IQ (at least 2 out of 3). Studies were excluded if participants were reported to have Axis I diagnoses (other than heroin dependence) or comorbidities known to impact neuropsychological functioning. Ten articles were coded and analyzed for the current study. Data synthesis When examined together, DSF and CPT evidenced a moderate and statistically significant effect size estimate (g = 0.614, p = .002). Subgroup analysis did not reveal statistically significant differences between the two groups (Q-Between = 0.228, p = 0.633). The effect size for DSF was g = 0.535 (p = 0.001) and for CPT was g = 0.774 (p = 0.104). The heterogeneity of DSF was in the moderate range, I2 = 71.291%, p = 0.002 while the heterogeneity of CPT was in the large range I2 = 97.863%, p = 0.001. Conclusion Heroin dependent individuals appear to demonstrate similarly poor performance on DSF and CPT. Assuming that both tests measure the same construct, both appear to be sensitive to the effect of Heroin on attention.

Objective Research suggests that cocaine and methamphetamine differ in their impact on executive functions (EF). The Paced Auditory Serial Addition Test (PASAT) is used to assess working memory; a component of EF. The purpose of this meta-analysis was to examine the difference between the effect of these two drugs on PASAT scores. Data Selection Three researchers independently searched nine databases (e.g., PsycINFO, Pubmed, ProceedingsFirst), extracted required data, and calculated effect sizes. Inclusion criteria identified studies that had (a) compared cocaine or methamphetamine dependent groups to healthy controls and (b) matched groups on either age, education, or IQ (at least 2 out of 3). Studies were excluded if participants were reported to have Axis I diagnoses (other than cocaine or methamphetamine dependence) or comorbidities known to impact neuropsychological functioning. Six articles were coded and analyzed for the current study. Data Synthesis Cocaine studies showed a medium statistically significant effect size (g = 0.370, p = 0.020), while methamphetamine did not (g = 0.198, p = 0.172). There was no heterogeneity in effect sizes for both drugs. Subgroup analysis found no significant difference between the two drugs on the PASAT (Q-between = 0.646, p = 0.421). Conclusions In contrast to methamphetamine, cocaine is associated with poorer performance on PASAT. This is in line with previous studies that found that cocaine had more significant impact on EF than methamphetamine. Given the preliminary nature of this meta-analysis and the small number of studies on the topic, future primary studies should directly contrast how these two drugs impact EF.

Objective The Category Test (CT) has consistently been found to be sensitive at detecting the effects of alcohol on the brain. However, this test has not been as widely used in examining the effects of methamphetamine. The current meta-analysis compared effect sizes of studies that have examined performance on the CT in alcohol versus methamphetamine dependent participants. Data selection Three researchers independently searched nine databases (e.g., PsycINFO, Pubmed, ProceedingsFirst), extracted required data, and calculated effect sizes. Inclusion criteria identified studies that had (a) compared alcohol or methamphetamine dependent groups to healthy controls and (b) matched groups on either age, education, or IQ (at least 2 out of 3). Studies were excluded if participants were reported to have Axis I diagnoses (other than alcohol or methamphetamine dependence) or comorbidities known to impact neuropsychological functioning. Sixteen articles were coded and analyzed for the current study. Data synthesis Alcohol studies showed a large effect size (g = 0.745, p < 0.001) while methamphetamine studies evidenced a moderate effect size (g = 0.406, p = 0.001); both without statistically significant heterogeneity (I2 = 0). Subgroup analysis revealed a statistically significant difference between the effect sizes from alcohol versus methamphetamine studies (Q-between = 5.647, p = 0.017). Conclusions The CT is sensitive to the effects of both alcohol and methamphetamine and should be considered when examining dependent patients who might exhibit problem solving, concept formation, and set loss difficulties in everyday living.