Gary C.K. Chan

Very young adolescents and alcohol : evidence of a unique susceptibility to peer alcohol use

AIM The aim of this study is to examine the susceptibility of very young adolescents (10-12 years of age) to peer alcohol-related influences, compared to older adolescents (13-14 years of age). METHODS The analysis sample consisted of 7064 adolescents in grade 6 (modal age 11) or grade 8 (modal age 13) from 231 schools in 30 communities across three Australian States. Key measures were adolescent reports of alcohol use (past 30 days) and the number of peers who consume alcohol without their parents awareness. Control variables included parent alcohol use, family relationship quality, pubertal advancement, school connectedness, sensation seeking, depression, length of time in high school, as well as age, gender, father/mother education, and language spoken at home. A multi-level model of alcohol use was used to account for school-level clustering on the dependent variable. RESULTS For both groups, the number of peers who consumed alcohol was associated with alcohol use, but Grade 6 students showed a unique susceptibility to peripheral involvement with peer drinking networks (having one friend who consumed alcohol). CONCLUSION The results point to the importance of monitoring and responding to comparatively minor shifts in the proportion of peers who use alcohol, particularly among very young adolescents.

Concurrent and Simultaneous Polydrug Use: Latent Class Analysis of an Australian Nationally Representative Sample of Young Adults

Background: Alcohol use and illicit drug use peak during young adulthood (around 18–29 years of age), but comparatively little is known about polydrug use in nationally representative samples of young adults. Drawing on a nationally representative cross-sectional survey (Australian National Drug Strategy Household Survey), this study examines polydrug use patterns and associated psychosocial risk factors among young adults (n = 3,333; age 19–29). Method: The use of a broad range of licit and illicit drugs were examined, including alcohol, tobacco, cannabis, cocaine, hallucinogens, ecstasy, ketamine, GHB, inhalants, steroids, barbiturates, meth/amphetamines, heroin, methadone/buprenorphine, other opiates, painkillers, and tranquilizers/sleeping pills. Latent class analysis was employed to identify patterns of polydrug use. Results: Polydrug use in this sample was best described using a 5-class solution. The majority of young adults predominantly used alcohol only (52.3%), alcohol and tobacco (34.18%). The other classes were cannabis, ecstasy, and licit drug use (9.4%), cannabis, amphetamine derivative, and licit drug use (2.8%), and sedative and alcohol use (1.3%). Young adult males with low education and/or high income were most at risk of polydrug use. Conclusion: Almost half of young adults reported polydrug use, highlighting the importance of post-high school screening for key risk factors and polydrug use profiles, and the delivery of early intervention strategies targeting illicit drugs.

A longitudinal study of the association of adolescent polydrug use, alcohol use and high school non-completion

AIMS Failure to complete high school predicts substantial economic and social disadvantage in adult life. The aim of this study was to determine the longitudinal association of mid-adolescent polydrug use and high school non-completion, relative to other drug use profiles. DESIGN A longitudinal analysis of the relationship between polydrug use in three cohorts at grade 9 (age 14-15 years) and school non-completion (reported post-high school). SETTING A State-representative sample of students across Victoria, Australia. PARTICIPANTS A total of 2287 secondary school students from 152 high schools. The retention rate was 85%. MEASUREMENTS The primary outcome was non-completion of grade 12 (assessed at age 19-23 years). At grade 9, predictors included 30-day use of eight drugs, school commitment, academic failure and peer drug use. Other controls included socio-economic status, family relationship quality, depressive symptoms, gender, age and cohort. FINDINGS Three distinct classes of drug use were identified-no drug use (31.7%), mainly alcohol use (61.8%) and polydrug use (6.5%). Polydrug users were characterized by high rates of alcohol, tobacco and cannabis use. In the full model, mainly alcohol users and polydrug users were less likely to complete school than non-drug users [odds ratio (OR) = 1.54, 95% confidence interval (CI) = 1.17-2.03) and OR = 2.51, 95% CI = 1.45-4.33), respectively, P < 0.001]. These effects were independent of school commitment, academic failure, peer drug use and other controls. CONCLUSIONS Mid-adolescent polydrug use in Australia predicts subsequent school non-completion after accounting for a range of potential confounding factors. Adolescents who mainly consume alcohol are also at elevated risk of school non-completion.

Estimating the number of regular and dependent methamphetamine users in Australia, 2002-2014

Objective: To estimate the number of regular and dependent methamphetamine users in Australia.

The topography of multiple drug use among adolescent Australians: findings from the National Drug Strategy Household Survey.

INTRODUCTION AND AIMS Despite evidence that many Australian adolescents have considerable experience with various drug types, little is known about the extent to which adolescents use multiple substances. The aim of this study was to examine the degree of clustering of drug types within individuals, and the extent to which demographic and psychosocial predictors are related to cluster membership. DESIGN AND METHOD A sample of 1402 adolescents aged 12-17 years were extracted from the Australian 2007 National Drug Strategy Household Survey. Extracted data included lifetime use of 10 substances, gender, psychological distress, physical health, perceived peer substance use, socioeconomic disadvantage, and regionality. Latent class analysis was used to determine clusters, and multinomial logistic regression employed to examine predictors of cluster membership. RESULT There were 3 latent classes. The great majority (79.6%) of adolescents used alcohol only, 18.3% were limited range multidrug users (encompassing alcohol, tobacco, and marijuana), and 2% were extended range multidrug users. Perceived peer drug use and psychological distress predicted limited and extended multiple drug use. Psychological distress was a more significant predictor of extended multidrug use compared to limited multidrug use. DISCUSSION AND CONCLUSION In the Australian school-based prevention setting, a very strong focus on alcohol use and the linkages between alcohol, tobacco and marijuana are warranted. Psychological distress may be an important target for screening and early intervention for adolescents who use multiple drugs.

Polysubstance use in cannabis users referred for treatment: drug use profiles, psychiatric comorbidity and cannabis-related beliefs.

Background: Population-based surveys demonstrate cannabis users are more likely to use both illicit and licit substances, compared with non-cannabis users. Few studies have examined the substance use profiles of cannabis users referred for treatment. Co-existing mental health symptoms and underlying cannabis-related beliefs associated with these profiles remains unexplored. Methods: Comprehensive drug use and dependence severity (Severity of Dependence Scale-Cannabis) data were collected on a sample of 826 cannabis users referred for treatment. Patients completed the General Health Questionnaire, Cannabis Expectancy Questionnaire, Cannabis Refusal Self-Efficacy Questionnaire, and Positive Symptoms and Manic-Excitement subscales of the Brief Psychiatric Rating Scale. Latent class analysis was performed on last month use of drugs to identify patterns of multiple drug use. Mental health comorbidity and cannabis beliefs were examined by identified drug use pattern. Results: A three-class solution provided the best fit to the data: (1) cannabis and tobacco users (n = 176), (2) cannabis, tobacco, and alcohol users (n = 498), and (3) wide-ranging substance users (n = 132). Wide-ranging substance users (3) reported higher levels of cannabis dependence severity, negative cannabis expectancies, lower opportunistic, and emotional relief self-efficacy, higher levels of depression and anxiety and higher manic-excitement and positive psychotic symptoms. Conclusion: In a sample of cannabis users referred for treatment, wide-ranging substance use was associated with elevated risk on measures of cannabis dependence, co-morbid psychopathology, and dysfunctional cannabis cognitions. These findings have implications for cognitive-behavioral assessment and treatment.

The relationship between psychological distress and adolescent polydrug use.

Polydrug use is relatively common among adolescents. Psychological distress is associated with the use of specific drugs, and may be uniquely associated with polydrug use. The purpose of this study was to test the association of psychological distress with polydrug use using a large adolescent sample. The sample consisted of 10,273 students aged 12-17 years from the State of Victoria, Australia. Participants completed frequency measures of tobacco, alcohol, cannabis, inhalant, and other drug use in the past 30 days, and psychological distress. Control variables included age, gender, family socioeconomic status, school suspensions, academic failure, cultural background, and peer drug use. Drug-use classes were derived using latent-class analysis, then the association of psychological distress and controls with drug-use classes was modeled using multinomial ordinal regression. There were 3 distinct classes of drug use: no drug use (47.7%), mainly alcohol use (44.1%), and polydrug use (8.2%). Independent of all controls, psychological distress was higher in polydrug users and alcohol users, relative to nondrug users, and polydrug users reported more psychological distress than alcohol users. Psychological distress was most characteristic of polydrug users, and targeted prevention outcomes may be enhanced by a collateral focus on polydrug use and depression and/or anxiety.

How important is the context of an adolescent's first alcoholic drink? Evidence that parental provision may reduce later heavy episodic drinking.

Objective: This study examined the extent to which a retrospective measure of parental provision of the first alcoholic beverage was related to current heavy episodic drinking and current responsible drinking practices. Sample: 608 14- to 17-year-olds from the 2007 Australian National Drug Strategy Household Survey. Measures: Source of first alcoholic beverage (friends/parents/others), source of current alcohol, age of onset of alcohol use, current responsible drinking practices, and proportion of current friends who drink. Results: Binary logistic and multiple regression procedures revealed that parental provision of an adolescent’s first alcoholic beverage predicted lower current heavy episodic drinking, and responsible drinking mediated this association. Discussion: The results suggested that for adolescents who become alcohol users, parental provision of the first drink may reduce subsequent alcohol-related risks compared to introduction to alcohol by friends and other sources. Alcohol-related risks remain significant for adolescents who consume alcohol, independent of who is the provider.

Association of different forms of bullying victimisation with adolescents’ psychological distress and reduced emotional wellbeing

Objective: The frequency and emotional response to bullying victimisation are known to be associated with adolescent mental ill health. A potentially important under-investigated factor is the form of bullying. Four common forms of bullying behaviours are name-calling, physical threats or harm, rumour spreading and social exclusion. To more comprehensively understand bullying victimisation in adolescence, we examined the association of all three factors (frequency, emotional response, form) to psychological distress and emotional wellbeing. Method: A stratified, random sample of adolescents (n = 10, 273; mean age = 14.33 years, standard deviation = 1.68 years) completed validated measures of bullying victimisation (Gatehouse Bullying Questionnaire), psychological distress (K10) and emotional wellbeing (Mental Health Inventory) in classroom time. Associations between the form of bullying victimisation and mental health outcomes were examined. Results: Adolescents reported a high prevalence of all four forms of bullying: teased or called names (30.6%), rumour spreading (17.9%), social exclusion (14.3%) and physical threats or harm (10.7%). Victimisation was independently associated with significantly higher levels of psychological distress and reduced levels of emotional wellbeing for all forms of bullying. In particular, social exclusion had a strong association with mental ill health. Adolescents who experienced frequent bullying that was upsetting reported higher psychological distress and reduced emotional wellbeing. Conclusion: Different forms of bullying victimisation were independently associated with psychological distress and reduced emotional wellbeing. In particular, frequent and upsetting social exclusion requires a targeted and measured response by school communities and health practitioners.

Proximate causes and possible adaptive functions of mast seeding and barren flower shows in spinifex grasses (Triodia spp.) in arid regions of Australia

Mast seeding, the intermittent production of large synchronised seed crops among plant populations, is a phenomenon that occurs at exceptionally long intervals in spinifex grasses (Triodia spp.) from arid regions of Australia. This is despite the reliance of these fire-sensitive plants on seeds for post-fire regeneration, and that spinifex grasslands rate among Australia’s most flammable ecosystems. The proximate causes and possible adaptive functions of masting in seven species of spinifex from arid regions within the 350-mm rainfall isohyet were investigated. Specifically, the seed set percentages of 79 specimens collected between 1947 and 2012 were related to the following environmental covariates: antecedent rainfall over 6, 12 and 36 months, relative humidity, and the number of days above 40°C and below 0°C during anthesis. Given the potential importance of seeding events for post-fire regeneration, it was also investigated whether masting in Triodia could represent a fire-related form of environmentally predictive masting, by testing whether high-yield years corresponded to years of increased fire occurrence. Examination of the dataset showed that 43% of specimens contained completely aborted inflorescences (0% seed fill), while seed set ranged from 2 to 69% in the remaining specimens. High levels of insect activity were also found, with 42% of specimens showing evidence of insect occupation. Statistical analyses showed that the main environmental driver of seed set was high precipitation over the previous 12 months, and that high-yield years were strongly related to years of increased fire likelihood. The number of days over 40°C was a weakly significant driver of yield, while the remaining covariates were not significant. It is hypothesised that intermittent reproduction by Triodia is a fire-related form of environmentally predictive masting, which maximises chances of post-fire regeneration by satiating seed predators during flammable periods (i.e. after heavy rain years). Furthermore, it is suggested that non-viable flower crops after initial low rainfalls may have an adaptive function, by diluting pre-dispersal seed predator densities with ‘decoy’ ovules that do not mature and lead to the starvation of developing larvae.