Alcohol consumption accounts for approximately 19% of DALYs (defined by WHO as one lost year of “healthy” life) and 27% of premature deaths amongst young people in high income countries (Toumbourou et al, 2007).

There are many studies examining the effects of prenatal alcohol exposure and the possible side effects on children living with parents with serious and long term alcohol problems, but little is known about how children may be affected by more normative patterns of drinking (e.g. drinking at lower risk levels and binge drinking).

Systematic reviews of prospective cohort studies offer the highest quality observational evidence for the assessment of the true consequences of parental drinking for development of alcohol use and related problems in young people. This is because cohort studies can determine the time order of exposure and outcome and rule out reverse causality.

The current study aimed to review whether and to what extent prospective cohort studies in the general population provide evidence for the true effects of parental drinking on their children’s alcohol use and problems, and to assess the quality of the evidence in terms of their capacity to draw causal inferences. It builds on a recent scoping review (Rossow et al, 2015) that identified 99 cohort studies of parental drinking and adverse outcomes in children.

Methods

A total of 21 studies were included, encompassing 26,354 families or parent-child dyads. As multiple study reports were based on the same cohorts, 16 distinct cohorts were identified and used in the analysis.

Studies were designated as having increased ability to show causality if they had:

1. A theory driven approach and analysis
2. Analytic rigor
3. Minimisation of sources of bias

The parental drinking exposure measure varied between studies with regard to type of drinking behaviour, age of exposure, relationship to outcomes and whose drinking behaviour was measured.

In 16 studies the outcome was one or several measures of drinking behaviour, in 5 studies the outcome was an alcohol-related problem (either as a single outcome or in addition to the drinking behaviour measure).

In 13 studies the outcome was obtained in teenage years, in 7 the outcome measure was obtained in young adulthood and in one study at the age of 10.

Due to this heterogeneity and a lack of data appropriate for meta-analysis authors undertook a narrative synthesis of study findings and risk of bias.

Results

• The majority of the studies (19 out of 21) reported at least one positive association between parental drinking and offspring’s alcohol-related outcome.
• The majority of the studies lacked an explicit theoretical conceptualisation of their research aims and none had a strong capacity for causal inference.
• Four studies showed some capacity for causal inference. All four of these studies found some evidence that parental drinking predicted drinking behaviour in offspring.
• Three of these studies had clear theory-driven analyses and looked at specific mediation mechanisms; specifically parenting practices, alcohol specific communication and poor inhibitory control in offspring.
• There were direct effects of paternal but not maternal drinking (Mares et al;, 2011), no mediation effect of poor inhibitory control in offspring (Pears et al., 2008) and a mediation effect of parental monitoring and discipline, which was stronger in early than late adolescence (Latendresse et al., 2007).
• It was noted that the lack of findings for maternal drinking and inhibitory control mediation effects could be due to poor statistical power in the studies.

Discussion

Nearly all cohort studies included in this review found that parental drinking predicts drinking behaviour in offspring. However, authors emphasise that consistency alone does not indicate a causal relationship, especially as there were mixed findings regarding the impact of maternal and paternal drinking, a lack of identification and control for relevant confounding factors and small data sets. An aim of this review was to evaluate the extent studies showed capacity for causal inferences, and overall it was found that there was a sparse use of theory driven analyses.

Limitations

Limitations identified in the review were the lack of standardisation of measurement in the literature, possible self-report bias for the exposure and outcome measures in the studies and publication bias.

Due to the lack of data appropriate for meta-analysis, authors undertook a narrative synthesis of the included studies. This type of analysis was deemed appropriate for the data, however it does not use techniques as reliable and rigorous as meta-analyses, therefore there is an increased potential for bias. This limitation is addressed in the review and authors emphasise that they have made their process of analysis as transparent as possible.

Conclusions

This is the first systematic review of cohort studies that investigates the capacity of specific studies to indicate causal relationships. This is necessary with cohort studies as confounding is a threat to their validity, where the outcome of interest is affected by other factors as well as the exposure of interest.

Authors conclude that more well-designed theory driven cohort studies are urgently needed so that from a “harms to others” framework interventions can be developed to prevent inter-generational alcohol problems.

Links

Primary paper

Rossow, I., Keating, P., Felix, L., & McCambridge, J. (2015). Does parental drinking influence children’s drinking? A systematic review of prospective cohort studies. Addiction, doi:10.1111/add.13097.

Other references

Latendresse, S., Rose, R., Viken, R., Pulkkinen, L., Kaprio, J. & Dick, D. (2008) Parenting mechanisms in links between parents’ and adolescents’ alcohol use behaviors. Alcoholism: Clinical and Experimental Research, 32, 322-30

Mares, S., van der Vorst, H., Engels, R. & Lichtwarck-Aschoff, A (2011). Parental alcohol use, alcohol-related problems, and alcohol-specific attitudes, alcohol-specific communication, and adolescent excessive alcohol use and alcohol-related problems: An indirect path model. Addictive Behaviors. 36, 209-16.

Pears, K., Capaldi, D. & Owen, L. (2007)  Substance use risk across three generations: the roles of parent discipline practices and inhibitory control. Psychology of Addictive Behaviors. 21, 373

Rossow, I., Felix, L., Keating, P. & McCambridge, J. (2015)Parental drinking and adverse outcomes in children – a scoping review of cohort studies. Drug and Alcohol Review.; in press

Toumbourou, J., Stockwell, T., Neighbors, C., Marlatt, G., Sturge, J. & Rehm, J. (2007) Interventions to reduce harm associated with adolescent substance use. The Lancet,. 369, 1391-401.

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