Krista Lisdahl Medina

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.

Impact of Adolescent Alcohol and Drug Use on Neuropsychological Functioning in Young Adulthood: 10-Year Outcomes

Because of ongoing neuromaturation, youth with chronic alcohol/substance use disorders (AUD/SUD) are at risk for cognitive decrements during young adulthood. We prospectively examined cognition over 10 years based on AUD/SUD history. Youth (N = 51) with no AUD/SUD history (n = 14), persisting AUD/SUD (n = 18), or remitted AUD/SUD (n = 19) were followed over 10 years with neuropsychological assessments. Groups were compared at baseline and 10-year follow-up. Both AUD/SUD groups declined in visuospatial construction at year 10 (p = .001). Further, cumulative alcohol use (p < .01) and drug withdrawal (p < .05) predicted year-10 visuospatial function. Alcohol use predicted verbal learning/memory (p < .05), while stimulant use predicted visual learning/memory (p = .01). More recent substance use predicted poorer executive function (p < .05). In conclusion, heavy alcohol and other substance use from adolescence through young adulthood may produce cognitive disadvantages, including visuospatial and memory decline. Youth with heavy, chronic alcohol use and/or drug withdrawal symptoms may be at particular risk.

Longitudinal study of cognition among adolescent marijuana users over three weeks of abstinence

BACKGROUND Cognitive deficits that persist up to a month have been detected among adult marijuana users, but decrements and their pattern of recovery are less known in adolescent users. Previously, we reported cognitive deficits among adolescent marijuana users after one month of abstinence (Medina, Hanson, Schweinsburg, Cohen-Zion, Nagel, & Tapert, 2007). In this longitudinal study, we characterized neurocognitive changes among marijuana-using adolescents across the first three weeks of abstinence. METHOD Participants were adolescent marijuana users with limited alcohol and other drug use (n=19) and demographically similar non-using controls (n=21) ages 15-19. Participants completed a brief neuropsychological battery on three occasions, after 3days, 2weeks, and 3weeks of stopping substance use. Abstinence was ascertained by decreasing tetrahydrocannabinol metabolite values on serial urine drug screens. Verbal learning, verbal working memory, attention and vigilance, and time estimation were evaluated. RESULTS Marijuana users demonstrated poorer verbal learning (p<.01), verbal working memory (p<.05), and attention accuracy (p<.01) compared to controls. Improvements in users were seen on word list learning after 2weeks of abstinence and on verbal working memory after 3weeks. While attention processing speed was similar between groups, attention accuracy remained deficient in users throughout the 3-week abstinence period. CONCLUSIONS This preliminary study detected poorer verbal learning and verbal working memory among adolescent marijuana users that improved during three weeks of abstinence, while attention deficits persisted. These results implicate possible hippocampal, subcortical, and prefrontal cortex abnormalities.

Prefrontal cortex morphometry in abstinent adolescent marijuana users: Subtle gender effects

Adult human studies suggest frontal dysfunction associated with chronic marijuana (MJ) use, but due to continued neuromaturation, adult studies may not generalize to adolescents. This study characterized prefrontal cortex (PFC) morphometry in chronic MJ‐using adolescents following 1 month of monitored abstinence. Data were collected from MJ users (n = 16) and controls (n = 16) aged 16–18. Extensive exclusionary criteria included co‐morbid psychiatric and neurologic disorders. Substance use and anatomical measures were collected after 28 days of monitored abstinence. PFC volumes were ascertained from manual tracing by reliable raters on high‐resolution magnetic resonance images. After controlling for lifetime alcohol use, gender and intracranial volume, MJ users did not differ from controls in PFC volume. However, marginal group‐by‐gender interactions were observed (P < 0.09): female MJ users demonstrated comparatively larger PFC volumes while male MJ users had smaller volumes compared with same‐gender controls. Further, group status and total PFC volume interacted in predicting executive functioning (P < 0.05). Among MJ users, smaller PFC total volume was associated with better executive functioning while the opposite pattern was seen among the controls. These preliminary results indicate that gender may moderate the relationship between MJ use and PFC morphometry. Given the relationship between larger PFC total volumes and poorer executive functioning among MJ users, female MJ users may be at increased risk for neurocognitive consequences. Future research will measure PFC gray and white matter separately and follow boys and girls over adolescence to examine the influence of MJ use on neurodevelopment.

Developmental Normative Data for the Corsi Block-Tapping Task

The Corsi Block-Tapping task has been utilized as a measure of spatial memory in both clinical and research contexts for several decades. Despite its wide application, the task has been employed with extraordinary variability in administration and scoring and in the composition of stimulus item sets. We have generated a set of test items containing quasi-randomly derived block-tapping sequences. In another study, we investigated item difficulty as a function of path configuration and showed a decline in performance with increasing span capacity load. In the current cross-sectional study, we evaluated developmental differences in span capacity by measuring performances of school children from grade 1 (M age = 7 years) to grade 8 (M age = 14) and a young adult sample (M age = 21 years). Mean span capacity increased incrementally and linearly with age, and no gender difference was observed. The increase in performance with advancing age supports the notion that spatial immediate memory capacity increases with maturation throughout childhood. Comparisons indicated that the span capacity of eighth graders (M = 6.9) was not statistically different from that of the young adults (M = 7.1), suggesting an upper developmental plateau for spatial span in early adolescence. This study provides a normative database for this widely utilized measure of spatial memory. Some of the data contained in this paper were presented at the meeting of the International Neuropsychological Society, Honolulu, February 2003.

Abnormal cerebellar morphometry in abstinent adolescent marijuana users.

Functional neuroimaging data from adults have, in general, revealed frontocerebellar dysfunction associated with acute and chronic marijuana (MJ) use. The goal of this study was to characterize cerebellar volume in adolescent chronic MJ users following 1 month of monitored abstinence. Participants were MJ users (n=16) and controls (n=16) aged 16-18 years. Extensive exclusionary criteria included history of psychiatric or neurologic disorders. Drug use history, neuropsychological data, and structural brain scans were collected after 28 days of monitored abstinence. Trained research staff defined cerebellar volumes (including three cerebellar vermis lobes and both cerebellar hemispheres) on high-resolution T1-weighted magnetic resonance images. Adolescent MJ users demonstrated significantly larger inferior posterior (lobules VIII-X) vermis volume than controls, above and beyond effects of lifetime alcohol and other drug use, gender, and intracranial volume. Larger vermis volumes were associated with poorer executive functioning. Following 1 month of abstinence, adolescent MJ users had significantly larger posterior cerebellar vermis volumes than non-using controls. These greater volumes are suggested to be pathological based on linkage to poorer executive functioning. Longitudinal studies are needed to examine typical cerebellar development during adolescence and the influence of marijuana use.

Gender effects on amygdala morphometry in adolescent marijuana users

Adolescent developments in limbic structures and the endogenous cannabinoid system suggest that teenagers may be more vulnerable to the negative consequences of marijuana use. This study examined the relationships between amygdala volume and internalizing symptoms in teenaged chronic marijuana users. Participants were 35 marijuana users and 47 controls ages 16-19 years. Exclusions included psychiatric (e.g., mood and anxiety) or neurologic disorders. Substance use, internalizing (anxiety/depression) symptoms and brain scans were collected after 28 days of monitored abstinence. Reliable raters manually traced amygdala and intracranial volumes on high-resolution magnetic resonance images. Female marijuana users had larger right amygdala volumes and more internalizing symptoms than female controls, after covarying head size, alcohol, nicotine and other substance use (p<0.05), while male users had similar volumes as male controls. For female controls and males, worse mood/anxiety was linked to smaller right amygdala volume (p<0.05), whereas more internalizing problems was associated with bigger right amygdala in female marijuana users. Gender interactions may reflect marijuana-related interruptions to sex-specific neuromaturational processes and staging. Subtle amygdala development abnormalities may underlie particular vulnerabilities to sub-diagnostic depression and anxiety in teenage female marijuana users.

The Influence of Recency of Use on fMRI Response During Spatial Working Memory in Adolescent Marijuana Users

Abstract Some neurocognitive recovery occurs within a month of abstinence from heavy marijuana use, yet functional magnetic resonance imaging (fMRI) has revealed altered activation among recent and abstinent adult users. We compared fMRl response during a spatial working memory (SWM) task between adolescent marijuana users with brief and sustained durations of abstinence. Participants were 13 recent users (two to seven days abstinent), 13 abstinent users (27 to 60 days abstinent), and 18 nonusing controls, all ages 15 to 18. Groups were similar on demographics, had no psychiatric or medical disorders, and user groups were similar on substance histories. Teens performed a two-back SWM task during fMRI. Recent users showed greater fMRI response in medial and left superior prefrontal cortices, as well as bilateral insula. Abstinent users had increased response in the right precentral gyrus (clusters ≥ 1328 μ1, p < .05). Results suggest that adolescents who recently used marijuana show increased brain activity in regions associated with working memory updating and inhibition. This study preliminarily suggests that (1) recent marijuana use may disrupt neural connections associated with SWM and result in compensatory brain response, and (2) sustained abstinence from marijuana may be associated with improvements in SWM response among adolescents.

Do Partners Agree About the Occurrence of Intimate Partner Violence? A Review of the Current Literature

Intimate partner violence (IPV) is a serious public health concern, and thus it is necessary to obtain accurate estimates of IPV. National surveys use two main methods of data collection: the proxy method and/or a method that obtains information from both members of the couple. There is controversy as to whether couples agree about the occurrence of IPV. Determining the extent to which partners agree about this is essential for gaining accurate prevalence rates. This article reviews literature on agreement within this field. The authors surveyed the major studies that have reported couple-level data. Agreement between the couples has been assessed in all of the reviewed research, with varying results. The majority of studies under consideration suggest that there is disagreement between partners about IPV. The authors propose that agreement levels should be high (indicated by several indexes) if the proxy method is to be used to assess prevalence rates.