Objective aerobic fitness level and neuropsychological functioning in healthy adolescents and emerging adults: Unique sex effects.

Objective: Research suggests positive relationships between aerobic fitness and cognition in older adults; however, limited research has adequately investigated the relationship between objectively measured aerobic fitness and broad cognitive functioning in healthy adolescents and young adults without psychiatric or physical health disorders. Further, studies to date have disproportionately examined males and failed to examine sex differences. Here we examine the relationship between aerobic fitness and neuropsychological functioning in physically healthy youth and whether sex moderates these findings. Design: Sixty-four healthy emerging adults (16-25 years-old; 32 female) underwent measurement of objective aerobic fitness (VO2 max) and neuropsychological assessment. Exclusion criteria included: left-handedness, prenatal medical issues or alcohol/illicit drug exposure, Axis-I psychiatric disorders, major medical disorders including metabolic conditions such as diabetes, hypertension, hyperlipidemia, major neurologic disorders, LOS greater than 2 min, intellectual disability or learning disability, regular substance use (e.g., greater than biweekly use of cannabis) or positive drug toxicology testing. Method: Multiple regressions examined VO2 max, sex, sex*VO2interaction in relation to neurocognition, controlling for objectively measured body fat percentage. Results: Prior to including body fat percentage, higher VO2 max related to improved working memory (Letter-Number Sequencing; p = .03) and selective attention (CPT-II hit response time standard error; p = .03). Aerobic fitness significantly interacted with sex, as higher-fit males had better performance on two sustained attention tasks while females did not demonstrate this pattern (CPT-II variability standard error, p = .047; Ruff 2&7 Total Speed, p = .02). Body fat percentage was positively slower cognitive flexibility (D-KEFS color-word switching/inhibition, p = .046). Conclusions: VO2 independently predicted better working memory and selective attention. Increased aerobic fitness level related to increased performance on sustained attention tasks in males but not females. Therefore, aerobic fitness may be positively related to better cognitive functioning in physically healthy adolescents and emerging adults without metabolic conditions. Further research into factors (e.g., intensity or type of activity) that may relate to beneficial outcomes by sex are needed.

Disrupted Resting State Attentional Network Connectivity in Adolescent and Young Adult Cannabis Users following Two-Weeks of Monitored Abstinence.

BACKGROUND: Numerous neuropsychological studies have shown that cannabis use during adolescence and young adulthood led to deficits in sustained and selective attention. However, few studies have examined functional connectivity in attentional networks among young cannabis users, nor have characterized relationships with cannabis use patterns following abstinence. METHODS: Differences in resting state functional connectivity (RSFC) within the dorsal (DAN) and ventral (VAN) attention networks were examined in 36 adolescent and young adult cannabis users and 39 non-substance using controls following two weeks of monitored abstinence. Observed connectivity differences were then correlated with past-year and lifetime cannabis use, length of abstinence, age of regular use onset, and Cannabis Use Disorder symptoms (CUD). RESULTS: After controlling for alcohol and nicotine use, cannabis users had lower RSFC within the DAN network, specifically between right inferior parietal sulcus and right anterior insula, as well as white matter, relative to controls. This region was associated with more severe cannabis use measures, including increased lifetime cannabis use, shorter length of abstinence, and more severe CUD symptoms. CONCLUSIONS: Findings demonstrate that regular cannabis use by adolescents and young adults is associated with subtle differences in resting state connectivity within the DAN, even after two weeks of monitored abstinence. Notably, more severe cannabis use markers (greater lifetime use, CUD symptoms, and shorter abstinence) were linked with this reduced connectivity. Thus, findings support public policy aimed at reducing and delaying cannabis use and treatments to assist with sustained abstinence. Future longitudinal studies are needed to investigate causation.

Stand-Biased Desks Impact on Cognition in Elementary Students Using a Within-Classroom Crossover Design.

Background: There is emerging literature that standing desk interventions may help to improve cognitive performance in school-aged children. The current study examines how desks that promote standing affect cognition over the course of a school year in third, fourth, and sixth graders. Methods: Nighty-nine students between the ages of 8 and 12 (M = 10.23; 58% Male) were assigned to either stand-biased desks or traditional sitting desks. A within-classroom design was used with students switching desks after 9 weeks. Cognitive assessments and teacher behavioral ratings were administered at baseline and readministered before students switched desks and at the conclusion of the study. Results: There were no significant effects on cognition or behavioral ratings from standing-biased desk intervention. Grade significantly moderated the relationship between stand-biased desks and cognition in that third graders showed increased cognitive control (p = 0.02, f2 = 0.06). Further, sex moderated the relationship in that females at stand-biased desks showed increased cognitive control (p = 0.03, f2 = 0.04). Conclusions: These results suggest that stand-biased desks impact cognition depending on grade and sex, indicating a complex relationship that should be teased out further in future research. Stand-biased desks showed moderate improvements in cognition and no deleterious effects, suggesting that they may be a helpful classroom intervention for children in elementary school.

Assessment of Withdrawal, Mood, and Sleep Inventories After Monitored 3-Week Abstinence in Cannabis-Using Adolescents and Young Adults.

Introduction: Among adolescents and young adults, cannabis use is prevalent. Prior studies characterizing withdrawal effects in this age range have primarily included treatment seeking or comorbid psychiatric samples; these studies have identified several affected domains, especially sleep, mood, and anxiety. The present study compared a community (i.e., nontreatment seeking) sample of cannabis-using and control participants on mood, anxiety, sleep, and withdrawal inventories during the course of a monitored 3-week cannabis abstinence period. Materials and Methods: Seventy-nine adolescent and young adult participants (cannabis-using group=37 and control group=42) were recruited from the community to undergo 3 weeks of confirmed abstinence (i.e., urine and sweat patch toxicology) and completion of Cannabis Withdrawal Symptom Criteria, State-Trait Anxiety Inventory, Beck's Depression Inventory, and Pittsburgh Sleep Quality Index across the study period. Repeated measures and cross-sectional regressions were used to examine main effects of group and interactions with time (where appropriate), while accounting for recent alcohol use and cotinine levels. Results: Cannabis-using participants reported higher mood (p=0.006), overall withdrawal (p=0.009), and sleep-related withdrawal (p<0.001) symptoms across abstinence compared to controls. Overall withdrawal severity (p=0.04) and sleep-related withdrawal symptoms (p=0.02) demonstrated a quadratic trajectory across the monitored abstinence periods, with an increase from baseline and subsequent decreases in symptom severity. No differences of anxiety scores (p=0.07) or trajectories (p=0.18) were observed. By study completion, groups did not differ among sleep quality components (all p's>.05). Conclusions: These findings revealed that nontreatment-seeking cannabis-using adolescents and young adults reported heightened total withdrawal symptoms during a 3-week sustained abstinence period relative to controls. Cannabis-using participants demonstrated an increase in withdrawal symptom trajectory during the first week followed by decreased symptoms from weeks 2 to 3, which contrasts with prior linear decreases observed in cannabis-using adolescent and young adults. More mood symptoms were observed in the cannabis-using group even while excluding for comorbid psychopathologies-along with significantly more sleep problems during the abstinence period. Implications include the necessity to provide psychoeducation for recreational, nontreatment-seeking cannabis-using individuals about cannabis withdrawal, mood symptoms, and sleep quality difficulties when cannabis cessation is attempted, to improve likelihood of long-term sustained abstinence.

Substance use patterns in 9 to 13-year-olds: Longitudinal findings from the Adolescent Brain Cognitive Development (ABCD) study.

Background: Though largely substance-naïve at enrollment, a proportion of the youth in the Adolescent Brain Cognitive Development (ABCD) Study are expected to initiate substance use (SU) as they transition into later adolescence. With annual data from youth 9-13 years-old, this study aims to describe their SU patterns over time. Here, prevalence rates of use are reported, along with predicted odds of use while analyzing common risk-factors associated with youth SU. Methods: The ABCD Study® enrolled 11,876 participants at Baseline (ages 9-10) and has followed them annually. Data through half of the third follow-up visit are available (ages 12-13; n = 6,251). SU descriptives for al psychoactive substances over time are outlined. General estimating equations (GEEs) assessed whether sociodemographic factors, internalizing and externalizing symptoms, and parental SU problems were associated with SU between Baseline and Y2 follow-up. Results: Across time, alcohol and nicotine remain the most used substances. Yearly rates of any SU increased (past year use: 13.9% in Y1; 14% Y2, 18.4% Y3). Cumulatively, by Y3, 39.7% of the cohort reported experimenting (e.g., sipping alcohol) with SU within their lifetime, while 7.4% reported a "full use" (a full alcohol drink, nicotine use, cannabis use, or any other SU) in their lifetime (past-year: 1.9% alcohol, 2.1% nicotine, 1.1% cannabis, 1.2% other substances). GEEs revealed ongoing longitudinal associations between sociodemographic factors, greater externalizing symptoms, and parental drug problems with increased odds of initiating SU. Conclusions: As ABCD participants transition into their teenage years, the cohort is initiating SU at increasing (though still low) rates.

Nicotine Effects on White Matter Microstructure in Young Adults.

OBJECTIVE: Nicotine use is widely prevalent among youth, and is associated with white matter microstructural changes as measured by diffusion tensor imaging (DTI). In adults, nicotine use is generally associated with lower fractional anisotropy (FA), but in adolescents/young adults (≤30 years), microstructure appears healthier, indicated by higher FA. This cross-sectional study examined associations between nicotine use and white matter microstructure using fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), and radial diffusivity (RD) in young adults. METHODS: Fifty-three participants (18 nicotine users [10 female]/35 controls [17 female]) ages 18-25 underwent MRI scan, neuropsychological battery, toxicology screening, and drug use interview. Nicotine group associations with FA and MD were examined in various white matter tracts. In significant tracts, AD and RD were measured. Exploratory correlations were conducted between significant tracts and verbal memory and sustained attention/working memory performance. RESULTS: Nicotine users exhibited significantly lower FA than controls in the left anterior thalamic radiation, left inferior longitudinal fasciculus, left superior longitudinal fasciculus-temporal, and left uncinate fasciculus. In these tracts, AD and RD did not differ, nor did MD differ in any tract. White matter quality was positively correlated with sustained attention/working memory performance. CONCLUSIONS: Cigarette smoking may disrupt white matter microstructure. These results are consistent with adult studies, but inconsistent with adolescent/young adult studies, likely due to methodological and sample age differences. Further studies should examine longitudinal effects of nicotine use on white matter microstructure in a larger sample.