BACKGROUND

Alcohol-related harm (see Saraceno; Munafo; Heron; Craddock, and van den Bree 2009) for more detail and references).

Alcohol is the most frequently used substance and alcohol involvement in young people has been associated with increased risk of tobacco and drug use, academic failure, traffic and other accidents, delinquency, pregnancy and sexually transmitted disease. Teenagers in the UK have one of the highest rates of substance use in Europe (European Monitoring Centre for Drugs and Drug Addiction). 21% of those aged 11-15 years report having used alcohol in the past week (Institute of Alcohol Studies, 2007). It is estimated that 1% of 14-16-year-olds in the UK drink alcohol nearly every day and are therefore at high risk of alcohol use disorder. Adolescence is a key developmental period with respect to future risk of alcohol use disorder. Studies indicate young people may have lower alcohol tolerance levels and become dependent at lower doses than adults. There is also increasing concern that ethanol can affect normal brain development during adolescence and thus interfere with cognitive and emotional functioning.

Depressive symptoms

Depression is a common mental health problem during adolescence. In the UK 5% of those aged 11-16 are affected with clinically diagnosed major depressive disorder or anxiety disorder. Alcohol problem use has been associated with depressive symptomatology in a number of adolescent samples and there is an increasing research and clinical interest in the aetiological relationships between both traits. Many studies indicate that depression plays an important role in the development of alcohol use disorder, however, the developmental relations between the traits remain unclear, with a number of studies reporting symptoms of depression precede alcohol problem use, while others report the opposite. There is a dearth of studies that have addressed these issues in large, longitudinal samples of young people.

Peer group behaviour

Peer substance use represents one of the strongest risk factors for the initiation as well as continuation of substance use/ misuse in adolescence. Adolescence is characterized by high vulnerability to social influences. Peers may exert their influences by serving as role models and influencing attitudes towards alcohol use or they can provide opportunities and encouragement for drinking and heavy alcohol use. Adolescents may seek out or be sought out by deviant peers because they share traits in common (e.g. deviance, or similar drinking habits).

The adolescent peer group can also influence (or moderate) the relationship between a risk-enhancing trait and substance misuse (Glaser et al., in press; D'Amico et al, 2005). D'Amico et al. reported that the relationship between adolescent substance use and alcohol abuse/ dependence at age 29 was influenced by pro-drug social influences in early adulthood (D'Amico; Ellickson; Collins; Martino, and Klein 2005). We previously found that childhood deviance increased risk of alcohol misuse in adolescence, but only in adolescents with alcohol using peers (Glaser et al. in press). In addition, the peer group (particularly peer rejection and victimization by peers) also plays an important role in depression in young people.

Sophisticated methods are needed to disentangle the complex relationships between peer influences, depression and alcohol misuse over time. For example, a longitudinal study by Aseltine et al. found that close relationships with friends protect against the development of depression, however, friendships with deviant peers on the other hand, have been reported to correlate positively with adolescent alcohol problem use.

Work that has preceded this proposal

Despite the documented strong influences of peers on adolescents' substance involvement and depressive symptoms, as far as we know, only one study has explored these relationships in more detail (Saraceno et al., about to be submitted). This study was part of a 3-year PhD project which focussed on the relationships between depressive symptoms in childhood (age 10) and alcohol problem use in early adolescence (age 14) in the large population-based Avon Longitudinal Study of Parents and Children (ALSPAC). We found that children with high levels of depressive symptoms had a 27% greater risk of alcohol misuse at age 14. However, this relationship was considerably stronger for girls than for boys. In addition, we found that not all adolescents with high levels of childhood depressive symptomatology had the same elevated risk of alcohol misuse. Rather, the strength of this relationship depended on (was moderated by) the peer group. That is, adolescents who experienced depressive symptoms in childhood were only at increased risk of alcohol misuse in adolescence if: a) they were firmly linked in with a friendship network; b) alcohol use/ misuse was common within this friendship network.

Currently proposed study

This study focussed on two time points only and we also only examined the relationship between earlier depressive symptoms (age 10) and later alcohol problems (age 14). That is, we did not examine the development of the relationships between depressive symptoms and alcohol use/ problem use over time. We also did not explore the factors that may contribute to the enhanced sensitivity to the influences of peers in adolescents with higher levels of depressive symptomatology. ALSPAC is uniquely suited to address these issues, because it represents one of the world's largest and most comprehensive cohort studies. Relevant information on depressive symptoms, alcohol use/ misuse and peer factors has been comprehensively assessed (from multiple informants to increase report reliability), using well-established measures on a number of occasions throughout the relevant period of young people's development. In addition, detailed information on other relevant factors that are likely to contribute the relationships specified above is available, i.e., family socio-economic status (SES), parental substance use/ misuse, parental depression, relations between family members. We are proposing to use ALSPAC data to examine the issues above.

AIMS are to examine:

1. How the relationships between depressive symptoms and alcohol use/ misuse are related across time and to what extent depressive symptoms increase risk for alcohol problem use and vise versa?;

2. The moderating role of the peer group (peer deviance and substance use) on the relationships between depressive symptoms and alcohol use;

3. To what extent social processes (i.e., young people's social acuity and histories of social interaction) predict deviance and substance use in the peer group in later adolescence;

4. To examine the interplay between social cognition and peer behaviour in the prediction of depressive symptoms and alcohol use.