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Open Access Publications from the University of California

Scholarly Works (8 results)

  • Article
  • Peer Reviewed
UC San Diego Previously Published Works (2014)

Objective

Adolescents who engage in regular marijuana use may have a higher propensity to take unsafe risks despite the possible negative consequences. We compared adolescents with a history of regular marijuana use to non-using teens on a behavioral measure of risk-taking. Given the involvement of the pre-frontal cortex in both risk-taking and executive functioning, we also examined whether risk-taking was associated with measures of executive functioning.

Method

Fifty-eight demographically similar community youth (ages 17-20; 29% female), including 24 marijuana users and 34 non-using controls, completed the computerized Balloon Analog Risk Task (BART; Lejuez et al., 2002) and measures of substance use and executive function. Primary BART outcome measures included total number of popped balloons and average adjusted pumps (mean pumps excluding popped balloons).

Results

Marijuana users had more popped balloons than controls (p<0.05) but did not differ on average adjusted pumps. Using hierarchical multiple regression controlling for age, riskier BART performance (popped balloons) was predictive of past 18-month hard drug use (β=0.30; p<0.05). Having a higher number of popped balloons was also predictive of past 18-month marijuana use (p<0.05), but age was a stronger predictor than marijuana use. Marijuana users performed worse on one test of executive functioning (psychomotor set-shifting, p<0.05), but this did not correlate with risk-taking.

Conclusions

Our finding of elevated risk-taking among marijuana users is consistent with previous research that substance users may have impaired risk processing. Further, our results suggest that risk-taking is not always associated with executive dysfunction, implying the involvement of distinct neural subsystems.
    Cover page: Adolescent marijuana users have elevated risk-taking on the balloon analog risk task
    • Article
    • Peer Reviewed
    UC San Diego Previously Published Works (2014)

    Background

    Negative affect and low distress tolerance have been associated with increased likelihood of alcohol consumption and relapse. This study utilized the Paced Auditory Serial Attention Test - Computerized Version (PASAT-C) to examine affective reactivity, cognitive performance, and distress tolerance during early abstinence among heavy drinking adolescents.

    Methods

    Participants, ages 16 to 18 (50% female), were 23 heavy episodic drinking youth (HED) and 23 demographically matched, nondrinking teens (CON). Both groups were drawn from the same schools and assessed at 3 time points: HED was first studied within 10 days (M = 4.26, SD = 4.4) of heavy episodic drinking and then at two 2-week intervals over 4 subsequent weeks of abstinence from alcohol and drugs. CON were studied at the same 2-week intervals.

    Results

    From the findings, it was observed that HED responded with greater emotional response to the PASAT-C (i.e., greater increases in frustration and irritability and greater decreases in happiness) at the initial assessment, but their affective responses diminished with sustained abstinence. CON and HED task performance did not differ at the initial assessment or across time. HED showed faster task discontinuation times to the PASAT-C at the first assessment, and both groups reduced task persistence across testings. Among HED, greater lifetime and recent alcohol consumption, alcohol-induced blackouts, and withdrawal symptoms were associated with increases in negative affect with PASAT-C exposure. Earlier age of onset of alcohol use was linked to poorer performance.

    Conclusions

    Heavy episodic drinking adolescents demonstrated heightened emotional reactivity and poorer distress tolerance to a cognitively challenging task during early abstinence. The combination of elevated negative affect and low distress tolerance may place adolescents at a heightened risk of escalations in or return to alcohol involvement.
      • Article
      • Peer Reviewed
      UC San Diego Previously Published Works (2014)
      The present study investigated the rate and pattern of neuropsychological recovery in heavy episodic drinking teens during the initial days to weeks of abstinence from alcohol. Adolescents (ages, 16-18 years) with histories of heavy episodic drinking (HED; N = 39) and socio-demographically similar control teens (CON; N = 26) were recruited from San Diego area schools. HED and CON were comparable on 5th grade standardized math and language arts test performance to ensure similar functioning before onset of substance use. Participants were administered three neuropsychological test batteries with 2-week intervals during a 4-week monitored abstinence period. HED teens performed worse overall than CON on tests of prospective memory (p = .005), cognitive switching (p = .039), inhibition task accuracy (p = .001), verbal memory (p's < .045), visuospatial construction (p's < .043), and language and achievement (p's < .008). The statistically significant group × time interaction for block design demonstrated normalization within the 4 weeks of abstinence for the HED (p = .009). This study identified cognitive performance deficits associated with heavy episodic drinking in adolescence during early abstinence and with sustained 4-week abstention. These findings suggest alcohol-related influences on several underlying brain systems that may predate the onset of alcohol abuse or dependence or take longer than 4 weeks to recover.
        • Article
        • Peer Reviewed
        UC San Diego Previously Published Works (2014)
        To assess recovery of cognitive effects, we investigated neuropsychological performance after 1 month of monitored abstinence in teens with histories of heavy episodic drinking, protracted marijuana use, or concomitant use of alcohol and marijuana. Adolescents (ages 16-18 years) with histories of heavy episodic drinking (HED; n=24), marijuana use (MJ; n=20), both heavy alcohol and marijuana use (HED+MJ; n=29), and socio-demographically similar control teens (CON; n=55) completed a neuropsychological battery following 4 weeks of monitored abstinence. Groups were similar on 5th grade standardized test scores, suggesting comparable academic functioning before onset of substance use. Relative to CON, HED showed poorer cognitive flexibility (p=.006), verbal recall (p=.024), semantic clustering (p=.011), and reading skills (p=.018). MJ performed worse than CON on inhibition task accuracy (p=.015), cued verbal memory (p=.031), and psychomotor speed (p=.027). Similar to HED youth, HED+MJ showed differences relative to CON on cognitive flexibility (p=.024) and verbal recall (p=.049). As with MJ teens, HED+MJ showed poorer task accuracy (p=.020). Unique to the HED+MJ group was poorer working memory (p=.012) relative to CON. For all substance using participants, worse performance across domains correlated with more lifetime use of alcohol and of marijuana, more withdrawal symptoms from alcohol, and earlier age of onset of marijuana use (ps<.05). Heavy alcohol use, marijuana use, and concomitant use of both substances during adolescence appear to be associated with decrements in cognitive functioning, and each substance (or combination of substances) may be linked to poorer performance in specific cognitive domains.
          • Article
          • Peer Reviewed
          UC San Diego Previously Published Works (2008)

          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.

            Cover page: Prefrontal cortex volumes in adolescents with alcohol use disorders: Unique gender effects
            • Article
            • Peer Reviewed
            UC San Diego Previously Published Works (2007)

            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.

              Cover page: Neuropsychological functioning in adolescent marijuana users: Subtle deficits detectable after a month of abstinence
              • Article
              • Peer Reviewed
              UC San Diego Previously Published Works (2021)

              Objective

              The evaluation of memory complaints in mild traumatic brain injury (mTBI) remains an important clinical consideration, especially in the context of comorbid psychiatric symptoms such as posttraumatic stress disorder (PTSD). We compared subjective memory complaints in veterans with and without a history of mTBI, examined ratings between those with single versus multiple mTBIs, and investigated associations between memory complaints and PTSD symptom severity.

              Methods

              117 outpatient veterans (mTBI: n = 79 [single mTBI: n = 22, multiple mTBI: n = 57], military controls [MCs]: n = 38) completed a TBI history assessment, the Prospective-Retrospective Memory Questionnaire (PRMQ), and the PTSD Checklist-Military Version (PCL-M).

              Results

              Hierarchical multiple regression showed that greater PCL-M scores significantly predicted elevated PRMQ-Total scores, accounting for 38% of the variance explained (P < .001). mTBI status predicted an additional 5% of variance in memory complaints (P < .01). The multiple-mTBI group endorsed more memory complaints than either MCs (P < .01) or the single-mTBI group (P < .05), who did not differ from MCs (P > .50).

              Conclusions

              Comorbid PTSD symptoms are an important factor when considering memory complaints in veterans with a reported history of mTBI. However, independent of comorbid PTSD symptoms, mTBI status-particularly in the context of repetitive neurotrauma-uniquely contributes to memory complaints. Findings suggest that veterans with a history of multiple mTBIs may be a particularly vulnerable group in need of specialized interventions and/or psychoeducation.
                Cover page: Research Letter: PTSD Symptom Severity and Multiple Traumatic Brain Injuries Are Associated With Elevated Memory Complaints in Veterans With Histories of Mild TBI
                • Article
                • Peer Reviewed
                UC San Diego Previously Published Works (2014)

                Objective

                We investigated using diffusion tensor imaging (DTI) and the association between white matter integrity and executive function (EF) performance in postacute mild traumatic brain injury (mTBI). In addition, we examined whether injury severity, as measured by loss of consciousness (LOC) versus alterations in consciousness (AOC), is related to white matter microstructural alterations and neuropsychological outcome.

                Participants

                Thirty Iraq and Afghanistan War era veterans with a history of mTBI and 15 healthy veteran control participants.

                Results

                There were no significant overall group differences between control and mTBI participants on DTI measures. However, a subgroup of mTBI participants with EF decrements (n = 13) demonstrated significantly decreased fractional anisotropy of prefrontal white matter, corpus callosum, and cingulum bundle structures compared with mTBI participants without EF decrements (n = 17) and control participants. Participants having mTBI with LOC were more likely to evidence reduced EF performances and disrupted ventral prefrontal white matter integrity when compared with either mTBI participants without LOC or control participants.

                Conclusions

                Findings suggest that altered white matter integrity contributes to reduced EF in subgroups of veterans with a history of mTBI and that LOC may be a risk factor for reduced EF as well as associated changes to ventral prefrontal white matter.
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