Spatial working memory performance and fMRI activation interactions in abstinent adolescent marijuana users

Previous studies have suggested neural disruption and reorganization in adult marijuana users. However, it remains unclear whether these effects persist in adolescents after 28 days of abstinence and, if they do, what Performance X Brain Response interactions occur. Adolescent marijuana users (n = 17). and controls (n = 17) aged 16-18 years were recruited from local schools. Functional magnetic resonance imaging data were collected after 28 days' monitored abstinence as participants performed a spatial working memory task. Marijuana users show Performance X Brain Response interactions in the bilateral temporal lobes, left anterior cingulate, left parahippocampal gyrus, and right thalamus (clusters : 1358 mu l- p <.05), although groups do not differ on behavioral measures of task performance. Marijuana users show differences in brain response to a spatial working memory task despite adequate performance, suggesting a different approach to the task via altered neural pathways

Reduced hippocampal volume among adolescents with alcohol use disorders without psychiatric comorbidity.

Studies have suggested that teens with alcohol use disorder (AUD) can demonstrate memory deficits, but the underlying neuroanatomical substrates are unclear. The hippocampus is crucial to intact memory functioning, and it actively develops during adolescence. The current study attempted to replicate and extend previous findings suggesting that adolescents with AUD show smaller hippocampal volumes than healthy adolescents. Manual tracings of bilateral hippocampi were performed on structural magnetic resonance images of 14 adolescents (ages 15 to 17 years) with AUD and 17 healthy comparison teens. Intracranial, white, and gray matter volumes, as well as memory abilities, were also measured. Results revealed that adolescents with AUD had significantly smaller left hippocampal volumes than healthy teens, even after removal of teens with comorbid conduct disorder from the analyses. In contrast, the groups did not differ in right hippocampal, intracranial, gray or white matter volumes, or memory performance. Hippocampal volumes were not related to alcohol-consumption rates. These findings indicate that adolescents with AUD, but free from other psychiatric comorbidities, have reduced left hippocampal volume. Because hippocampal volume did not relate to alcohol use characteristics, it is possible that premorbid volumetric differences could account for some of the observed group differences in hippocampal volume. (c) 2005 Elsevier Ireland Ltd. All rights reserved

fMRI response to spatial working memory in adolescents with comorbid marijuana and alcohol use disorders

Alcohol and marijuana use are prevalent in adolescence, yet the neural impact of concomitant use remains unclear. We previously demonstrated functional magnetic resonance imaging (fMRI) response to spatial working memory (SWM) among teens with alcohol use disorders (AUD) compared to controls, and predicted that adolescents with marijuana aid alcohol use disorders would show additional abnormalities. Participants were three groups of 15-17-year-olds: 19 non-abusing controls, 15 AUD teens with limited exposure to drugs, and 15 teens with comorbid marijuana and alcohol use disorders (MAUD) and minimal other drug experience. After > 2 days' abstinence, participants performed a SWM task during fMRI acquisition. fMRI brain response patterns differed between groups, despite similar performance on the task. MAUD youths showed less activation in inferior frontal and temporal regions than controls, and more response in other prefrontal regions. Compared to AUD teens, MAUD youths also showed less inferior frontal and temporal activation, but more medial frontal response. Overall, MAUD youths showed different brain response abnormalities than teens with AUD alone, despite relatively short histories of substance involvement. This pattern could suggest compensation for marijuana-related attention and working memory deficits. However, relatively recent use and premorbid features may influence results, and should be examined in future studies. (c) 2005 Elsevier Ireland Ltd. All rights reserved

Prefrontal cortex volumes in adolescents with alcohol use disorders: Unique gender effects

Background: Adolescents with alcohol use disorders (AUD) have shown smaller prefrontal cortex (PFC) volumes compared with healthy controls; however, differences may have been due to comorbid disorders. This study examined PFC volumes in male and female adolescents with AUD who did not meet criteria for comorbid mood or attention disorders.Methods: Participants were adolescents aged 15 to 17 who met criteria for AUD (n = 14), and demographically similar healthy controls (n = 17). Exclusions included any history of a psychiatric or neurologic disorder other than AUD or conduct disorder. Magnetic resonance imaging scans occurred after at least 5 days of abstinence from alcohol or drugs. Overall PFC volumes and white matter PFC volumes were compared between groups.Results: After controlling for conduct disorder, gender, and intracranial volume, AUD teens demonstrated marginally smaller anterior ventral PFC volumes (p = 0.09) than controls, and significant interactions between group and gender were observed (p < 0.001 to p < 0.03). Compared with same-gender controls, females with AUD demonstrated smaller PFC volumes, while males with AUD had larger PFC volumes. The same pattern was observed for PFC white matter volumes.Conclusions: Consistent with adult literature, alcohol use during adolescence is associated with prefrontal volume abnormalities, including white matter differences. However, adolescents with AUD demonstrated gender-specific morphometric patterns. Thus, it is possible that gender may moderate the impact of adolescent alcohol use on prefrontal neurodevelopment, and the neurodevelopmental trajectories of heavy drinking boys and girls should be evaluated separately in longitudinal studies

Prefrontal cortex volumes in adolescents with alcohol use disorders: Unique gender effects

Background: Adolescents with alcohol use disorders (AUD) have shown smaller prefrontal cortex (PFC) volumes compared with healthy controls; however, differences may have been due to comorbid disorders. This study examined PFC volumes in male and female adolescents with AUD who did not meet criteria for comorbid mood or attention disorders.Methods: Participants were adolescents aged 15 to 17 who met criteria for AUD (n = 14), and demographically similar healthy controls (n = 17). Exclusions included any history of a psychiatric or neurologic disorder other than AUD or conduct disorder. Magnetic resonance imaging scans occurred after at least 5 days of abstinence from alcohol or drugs. Overall PFC volumes and white matter PFC volumes were compared between groups.Results: After controlling for conduct disorder, gender, and intracranial volume, AUD teens demonstrated marginally smaller anterior ventral PFC volumes (p = 0.09) than controls, and significant interactions between group and gender were observed (p < 0.001 to p < 0.03). Compared with same-gender controls, females with AUD demonstrated smaller PFC volumes, while males with AUD had larger PFC volumes. The same pattern was observed for PFC white matter volumes.Conclusions: Consistent with adult literature, alcohol use during adolescence is associated with prefrontal volume abnormalities, including white matter differences. However, adolescents with AUD demonstrated gender-specific morphometric patterns. Thus, it is possible that gender may moderate the impact of adolescent alcohol use on prefrontal neurodevelopment, and the neurodevelopmental trajectories of heavy drinking boys and girls should be evaluated separately in longitudinal studies

Neuropsychological functioning in adolescent marijuana users: Subtle deficits detectable after a month of abstinence

In adults. Studies examining the long-lasting cognitive effects of marijuana use demonstrate subtle deficits in attention. executive function. and memory. Because neuromaturation continues through adolescence, these results cannot necessarily generalize to adolescent marijuana users. The goal of this Study was to examine neuropsychological functioning in abstinent marijuana using and demographically similar control adolescents. Data were collected from 65 adolescent marijuana users (n = 31, 26% females) and controls (n 34, 26% females) 16-18 years of age. Extensive exclusionary criteria included independent psychiatric, medical, and neurologic disorders. Neuropsychological assessments were conducted after > 23 days of monitored abstinence. After controlling for lifetime alcohol use and depressive symptoms, adolescent marijuana users demonstrated slower psychomotor speed (p < .05), and poorer complex attention (p < .04), story memory (p < .04), and planning and sequencing ability (p < .001) compared with controls. Post hoc analysis revealed that the number of lifetime marijuana use episodes was associated with poorer cognitive function, even after controlling for lifetime alcohol use. The general pattern of results suggested that, even after a month of monitored abstinence, adolescent marijuana users demonstrate subtle neuropsychological deficits compared with nonusers. It is possible that frequent marijuana use during adolescence may negatively influence neuromaturation and cognitive development

Blood oxygen level dependent response and spatial working memory in adolescents with alcohol use disorders

Background: Previous studies have suggested neural disruption and reorganization in young and older adults with alcohol use disorders (AUD). However, it remains unclear at what age and when in the progression of AUD changes in brain functioning might occur. Methods: Alcohol use disordered (n = 15) and nonabusing (n = 19) boys and girls aged 15 to 17 were recruited from local high schools. Functional magnetic resonance imaging data were collected after a minimum of 5 days' abstinence as participants performed spatial working memory and simple motor tasks. Results: Adolescents with AUD showed greater brain response to the spatial working memory task in bilateral parietal cortices and diminished response in other regions, including the left precentral gyros and bilateral cerebellar areas (clusters 943 mul; p < 0.05), although groups did not differ on behavioral measures of task performance. No brain response differences were observed during a simple finger-tapping task. The degree of abnormality was greater for teens who reported experiencing more withdrawal or hangover symptoms and who consumed more alcohol. Conclusions: Adolescents with AUD show abnormalities in brain response to a spatial working memory task, despite adequate performance, suggesting that subtle neuronal reorganization may occur early in the course of AUD