Adolescents who show signs of alcohol dependence are more likely to develop depression by their mid-20s, according to a new study.
Researchers at University College London (UCL) and the University of Bristol also found that drinking large amounts of alcohol regularly, but with no signs of dependency, did not predict the risk of depression.
The study, published in The Lancet Psychiatry, looked at the association between alcohol consumption and signs of problematic drinking, or dependence, at the age of 18, and depression 6 years later at the age of 24.
Signs of alcohol dependence include an inability to stop drinking, failure to meet normal expectations due to drinking, and feeling a need to drink after a heavy session, as well as harmful effects like memory loss related to drinking.
Avon Longitudinal Study Findings
The study involved 3902 participants of the Children of the 90’s birth cohort study (Avon Longitudinal Study of Parents and Children – ALSPAC), a longitudinal cohort of parents and their children born in South West England in 1991 and 1992, who have been surveyed at regular intervals.
The researchers found that those who appeared to be dependent on alcohol at age 18 (or at any age from 17 to 22) were more likely than their peers to have depression at the age of 24.
Those with a score of zero on the alcohol dependence scale at age 18 faced an 11% probability of depression by age 24, compared with 15% for those with a score of one on the scale.
An increase from zero to one on the alcohol dependency scale represented a 28% increase in the probability of not being able to stop drinking once started and a 33% increase in the probability of failing to do what was normally expected of you.
This relationship remained after researchers had taken into consideration other factors like substance use and depressive symptoms at the age of 16 years.
Researchers said this indicated that there may be a causal relationship between alcohol dependence and subsequent depression that is not explained by poor overall mental health in adolescence.
High Consumption Still an Issue
The researchers said the fact that consumption levels by themselves were not associated with an increased risk of depression, might be partly due to the fact that drinking in late adolescence is often tied with social contact and reflects social norms.
Co-lead author Dr Gemma Hammerton, from the University of Bristol, said: "While we found that alcohol consumption alone did not appear to increase the probability of depression, heavy drinking can be a precursor to dependence, and can have harmful physical health impacts in the longer term as well. High frequency and quantity of alcohol consumption, therefore, remain important as targets to prevent or reduce during adolescence."
She added: "Public health interventions to prevent depression could target problematic alcohol use (such as if alcohol is having a negative impact on a person’s personal relationships or responsibilities), which is likely to occur before dependence, and involve high frequency and quantity of consumption."
The findings suggested that preventing alcohol dependence during adolescence, or treating it early, could reduce the risk of depression.
Co-lead author Dr Gemma Lewis, from UCL Psychiatry said: "Problematic drinking patterns could be a warning sign of future mental health problems, so helping young people to avoid problematic alcohol use could have long-term benefits to their mental health."
The study found some evidence that psychosocial interventions targeting excessive alcohol use among adolescents in higher education reduced depressive symptoms. It said behavioural interventions, such as the Drink Less smartphone app, were also being evaluated. The study also mentioned evidence that price increases for alcoholic drinks are known to reduce rates of consumption in the general population and in high-risk groups, such as heavier drinkers and young people.
Alcohol Consumption Falling
Mark Leyshon, senior research and policy manager at Alcohol Change UK, said: "Alcohol consumption amongst 18- to 24-year-olds has been falling for some time. However, there remains a significant number of young people who use alcohol in a harmful way.
"There were over 40,000 alcohol-related hospital admissions amongst under 24s in 2019, and more than a quarter of these were for mental and behavioural disorders as a result of alcohol.
"The findings from this new study reinforce the importance of protecting young people from alcohol harm, through early intervention and proper funding of youth addictions services so that the right support and treatment is there for everyone who needs it."
The study was funded by the Medical Research Council and Alcohol Research UK, now known as Alcohol Change UK. MH has served as Trustee of Society of Study of Addiction and Regional Editor of Addiction in the past 3 years. All other authors declare no competing interests.