Gemma Hammerton, PhD: Adolescent Alcohol Dependence and Adult Depression

Recent research conducted by Gemma Hammerton, PhD, at the Population Health Sciences, Bristol Medical School, University of Bristol, suggested alcohol dependence during adolescence may increase the risk of depression in young adulthood.¹

However, the data showed alcohol consumption alone does not seem to have a significant impact on depression risk, indicating it is the presence of alcohol dependence that plays a more substantial role in predicting depression later in life.

Hammerton further explained the details of the investigation and her findings in a written interview with HCPLive.

Can you explain the main objective of your study and what prompted you to investigate the link between alcohol dependence during adolescence and the risk of depression in young adulthood?

Hammerton: The main objective of our study was to investigate whether alcohol dependence, but not high frequency or quantity of consumption, during adolescence was associated with depression in young adulthood.

We wanted to examine the relationship between alcohol dependence during adolescence and depression in young adulthood because, if there is evidence that this relationship is causal, there would be important public health implications.

Depression causes a large public health burden, and alcohol-related behavior is a potentially modifiable risk factor. Given the rich data we had available, we felt we could make an important contribution to the current evidence base.

The study used the Avon Longitudinal Study of Parents and Children data. What were the key factors that led you to select this particular cohort for your research?

Using the Avon Longitudinal Study of Parents and Children (ALSPAC) allowed us to examine our research questions using a large contemporary sample. Most of the previous research in this area has been conducted using data from the USA or New Zealand, so we felt it was important to examine if the findings generalized to a UK-based sample.

Additionally, ALSPAC has rich data available on potential confounders (including sex, sociodemographic factors, parental mental health and alcohol use, child behavioral problems, being bullied, substance use, and depression symptoms), prospective repeated measures of both alcohol consumption and dependence across adolescence and depression diagnosis in early adulthood.

These data allowed us to robustly examine the effects of alcohol dependence and consumption at different time points during adolescence, and the rate by which they increase depression in young adulthood.

Your findings indicated a positive link between alcohol dependence at age 18 and depression at age 24. Could you discuss the potential mechanisms behind this association and what implications it may have for addressing mental health concerns in young adults?

Alcohol dependence is associated with a wide range of physical, psychological, interpersonal, social, educational, and economic consequences that could lead to depression. Two potential mechanisms for the association between alcohol dependence and depression could include antisocial behavior and cannabis use; however, there are many other possible explanations, and these are important to examine in future research.

Our findings suggest that preventing alcohol dependence during adolescence, or potentially treating it early, could reduce the risk of future depression in young adults. We did not find an association between high frequency and quantity of alcohol consumption and depression; however, heavy alcohol consumption is likely to precede dependence.

Therefore, high frequency and quantity of alcohol consumption are still important to prevent or reduce during adolescence, especially given its associations with other harms, such as injury and antisocial behavior. Public health interventions to prevent depression among young people could target subthreshold levels of alcohol dependence, which are likely to involve high frequency and quantity of consumption.

Additionally, public health messages to prevent depression that are aimed at young people could emphasize dependent aspects of drinking that are harmful.

Can you elaborate on the contrasting findings which showed no significant association between the rate of change in alcohol dependence and depression?

We found no evidence that a faster increase in levels of dependence across adolescence was associated with depression in young adulthood and only small variability in the rate of change over time.

This finding suggests the magnitude of the association between dependence and depression is fairly constant over adolescence and that the time point for considering levels of alcohol dependence (between ages 16 and 23 years) might not be particularly important.

Do you have any future plans in your research agenda regarding alcohol dependence, depression, and their interplay in young adulthood? Are there any specific areas you believe need further investigation to build on the current knowledge?

It would be useful to examine this same research question in other contexts, particularly outside of high-income countries, where the majority of research has been conducted to date.

We would like to take these findings forward and examine potential mechanisms of the association between alcohol dependence and later depression, for example, whether the relationship is explained by antisocial behavior or cannabis use, and examine the role of neuroticism (as suggested in a commentary based on the article in Lancet Psychiatry). ALSPAC has data available that could be used to address these questions.

References:

1. Grossi, G. Targeting Adolescent Alcohol Dependence May Prevent Depression in Young Adults. HCPLive. July 19, 2023. https://www.hcplive.com/view/targeting-adolescent-alcohol-dependence-prevent-depression-young-adults