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Overall, cocaine and methamphetamine users share similar neuropsychological profiles. However, cocaine appears to be more associated with working memory impairments, which are typically frontally mediated, while methamphetamine appears to be more associated with memory impairments that are linked with temporal and parietal lobe dysfunction.

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BackgroundIn mental health, comorbidities are the norm rather than the exception. However, current meta-analytic methods for summarizing the neural correlates of mental disorders do not consider comorbidities, reducing them to a source of noise and bias rather than benefitting from their valuable information.ObjectivesWe describe and validate a novel neuroimaging meta-analytic approach that focuses on comorbidities. In addition, we present the protocol for a meta-analysis of all major mental disorders and their comorbidities.MethodsThe novel approach consists of a modification of Seed-based d Mapping—with Permutation of Subject Images (SDM-PSI) in which the linear models have no intercept. As in previous SDM meta-analyses, the dependent variable is the brain anatomical difference between patients and controls in a voxel. However, there is no primary disorder, and the independent variables are the percentages of patients with each disorder and each pair of potentially comorbid disorders. We use simulations to validate and provide an example of this novel approach, which correctly disentangled the abnormalities associated with each disorder and comorbidity. We then describe a protocol for conducting the new meta-analysis of all major mental disorders and their comorbidities. Specifically, we will include all voxel-based morphometry (VBM) studies of mental disorders for which a meta-analysis has already been published, including at least 10 studies. We will use the novel approach to analyze all included studies in two separate single linear models, one for children/adolescents and one for adults.DiscussionThe novel approach is a valid method to focus on comorbidities. The meta-analysis will yield a comprehensive atlas of the neuroanatomy of all major mental disorders and their comorbidities, which we hope might help develop potential diagnostic and therapeutic tools.

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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.