Differential effects of acute alcohol on prepulse inhibition and event-related potentials in adolescent and adult Wistar rats

Background: Previous studies have demonstrated that adolescent and adult rats show differential sensitivity to many of the acute effects of alcohol. We recently reported evidence of developmental differences in the effects of acute alcohol on the cortical electroencephalogram. However, it is unclear whether developmental differences are also observed in other neurophysiological and neurobehavioral measurements known to be sensitive to alcohol exposure. The present study determined the age‐related effects of acute alcohol on behavioral and event‐related potential (ERP) responses to acoustic startle (AS) and prepulse inhibition (PPI). Methods: Male adolescent and adult Wistar rats were implanted with cortical recording electrodes. The effects of acute alcohol (0.0, 0.75, and 1.5 g/kg) on behavioral and ERP responses to AS and PPI were assessed. Results: Acute alcohol (0.75 and 1.5 g/kg) significantly reduced the behavioral and electrophysiological response to AS in adolescent and adult rats. Both 0.75 and 1.5 g/kg alcohol significantly enhanced the behavioral response to PPI in adolescent, but not in adult rats. During prepulse + pulse trials, 1.5 g/kg alcohol significantly increased the N10 pulse response in the adolescent frontal cortex. Acute alcohol (0.75 and 1.5 g/kg) also increased the N1 ERP pulse response to prepulse stimuli in frontal and parietal cortices in adult rats, but not in adolescent rats. Conclusions: These data suggest that alcohol’s effect on behavioral and electrophysiological indices of AS do not differ between adults and adolescents whereas developmental stage does appear to significantly modify alcohol‐influenced response to PPI.     

Do maternal parenting practices predict problematic patterns of adolescent alcohol consumption?

Objective This study examines whether a mother's style of parenting at child age 5 years predicts problematic patterns of drinking in adolescence, after controlling for relevant individual, maternal and social risk factors. Methods Data were used from the Mater‐University Study of Pregnancy, an Australian longitudinal study of mothers and their children from pregnancy to when the children were 14 years of age. Logistic regression analyses examined whether maternal parenting practices at child age 5 predicted problematic drinking patterns in adolescence, after controlling for a range of confounding covariates. Results Physical punishment at child age 5 did not predict adolescent alcohol problems at follow‐up. Results indicated that low maternal control at child age 5 predicted adolescent occasional drinking patterns at age 14. More frequent maternal partner change coupled with lower levels of control was the strongest predictor of more problematic patterns of drinking by adolescents. Conclusions These findings highlight the importance of family structure and level of parental control in the development of problematic patterns of drinking in adolescence.     

Trends in adolescent alcohol use: effects of age, sex and cohort on prevalence and heritability

Aims To determine the effect of age, sex and cohort on the prevalence and genetic architecture of adolescent alcohol use (AAU). Design Survey study in participants registered with the Netherlands Twin Register. Setting Twins from the general population. Participants Two cohorts (data collected in 1993 and 2005–08) of twins aged 13–15, 16–17 and 18–21 years. In 1993 and 2005–08 a total of 3269 and 8207 twins, respectively, took part. Measurements Survey data on initiation and frequency of alcohol use and quantity of alcohol consumed. Findings The prevalence of alcohol initiation increased between 1993 and 2005–08 for both males and females. The largest difference was for girls observed at ages 13–15, where the prevalence increased from 59.5% to 72.4%. We also found increases in prevalence across cohorts for quantity of alcohol consumed and non‐significant increases for frequency of alcohol use. From age 16 onwards, boys drank more frequently and larger quantities than girls. Genetic model fitting revealed that the genetic architecture of AAU did not differ between birth cohorts, nor were there differences between boys and girls. Genetic factors explained between 21% and 55% of individual differences in alcohol measures throughout adolescence. Shared environment explained between 17% and 64% of variance in alcohol use, across different age groups and alcohol measures. Conclusions In the Netherlands, the prevalence of alcohol initiation, frequency and quantity has increased in adolescents over a 15‐year period, but there are no changes in the genetic architecture of adolescent alcohol use.     

Gender differences in the impact of families on alcohol use: a lagged longitudinal study of early adolescents

Aims From the pre‐teen to the mid‐teen years, rates of alcohol use and misuse increase rapidly. Cross‐sectional research shows that positive family emotional climate (low conflict, high closeness) is protective, and there is emerging evidence that these protective mechanisms are different for girls versus boys. The aim of this study was to explore gender differences in the longitudinal impact of family emotional climate on adolescent alcohol use and exposure to peer drinking networks. Design Three‐wave two‐level (individual, within‐individual over time) ordinal logistic regression with alcohol use in the past year as the dependent measure and family variables lagged by 1 year. Setting Adolescents completed surveys during school hours. Participants A total of 855 Australian students (modal age 10–11 years at baseline) participating in the International Youth Development Study (Victoria, Australia). Measurements These included emotional closeness to mother/father, family conflict, parent disapproval of alcohol use and peer alcohol use. Findings For girls, the effect of emotional closeness to mothers on alcohol use was mediated by exposure to high‐risk peer networks. Parent disapproval of alcohol use was protective for both genders, but this effect was larger for boys versus girls, and there was no evidence that peer use mediated this effect. Peer drinking networks showed stronger direct risk effects than family variables. Conclusions Family factors unidirectionally impact on growth in adolescent alcohol use and effects vary with child gender.     

Trajectories of adolescent alcohol and cannabis use into young adulthood

BACKGROUND: Both alcohol and cannabis use carry health risks. Both are commonly initiated in adolescence. To date little research has described trajectories of adolescent cannabis or alcohol use or compared their respective consequences in young adulthood. METHODS: The design was a 10-year eight-wave cohort study of a state-wide community sample of 1943 Victorians initially aged 14-15 years. Moderate- and high-risk alcohol use was defined according to total weekly alcohol consumption. Moderate- and high-risk cannabis use were defined as weekly and daily use, respectively. RESULTS: Around 90% of young adults used either alcohol or cannabis. Although an association existed between alcohol and cannabis use, there was a tendency for heavy users to use one substance predominantly at any one time. Weekly or more frequent cannabis use in the absence of moderate-risk alcohol use in teenagers predicted a sevenfold higher rate of daily cannabis use in young adults but only a twofold increase in high-risk alcohol use. Conversely, moderate-risk adolescent alcohol use in the absence of weekly cannabis predicted an approximately threefold increased rate of both high-risk drinking and daily cannabis use in young adulthood. Selective heavy cannabis use in both adolescence and young adulthood was associated with greater illicit substance use and poorer social outcomes in young adulthood than selective alcohol use. CONCLUSIONS: Heavier teenage cannabis users tend to continue selectively with cannabis use. Considering their poor young adult outcomes, regular adolescent cannabis users appear to be on a problematic trajectory.     

Neural correlates of verbal learning in adolescent alcohol and marijuana users

Aims Alcohol and marijuana are the most widely used intoxicants among adolescents, yet their potential unique and interactive influences on the developing brain are not well established. Brain regions subserving learning and memory undergo continued maturation during adolescence, and may be particularly susceptible to substance‐related neurotoxic damage. In this study, we characterize brain response during verbal learning among adolescent users of alcohol and marijuana. Design Participants performed a verbal paired associates encoding task during functional magnetic resonance imaging (fMRI) scanning. Setting Adolescent subjects were recruited from local public schools and imaged at a university‐based fMRI center. Participants Participants were 74 16–18‐year‐olds, divided into four groups: (i) 22 controls with limited alcohol and marijuana experience, (ii) 16 binge drinkers, (iii) eight marijuana users and (iv) 28 binge drinking marijuana users. Measurements Diagnostic interview ensured that all teens were free from neurological or psychiatric disorders; urine toxicology and breathalyzer verified abstinence for 22–28 days before scanning; a verbal paired associates task was administered during fMRI. Findings Groups demonstrated no differences in performance on the verbal encoding task, yet exhibited different brain response patterns. A main effect of drinking pointed to decreased inferior frontal but increased dorsal frontal and parietal fMRI response among binge drinkers (corrected P < 0.05). There was no main effect of marijuana use. Binge drinking × marijuana interactions were found in bilateral frontal regions (corrected P < 0.05), where users of either alcohol or marijuana showed greater response than non‐users, but users of both substances resembled non‐users. Conclusions Adolescent substance users demonstrated altered fMRI response relative to non‐using controls, yet binge drinking appeared to be associated with more differences in activation than marijuana use. Alcohol and marijuana may have interactive effects that alter these differences, particularly in prefrontal brain regions.