With the party season ahead, many of us will indulge in the odd tipple at the office Christmas party or enjoy a drink or two with friends and family. But why do some of us wake up feeling horrendous the next morning, while others are seemingly unaffected by overindulgence? New research suggests that whether we suffer a debilitating hangover the next day could be influenced by our genes.
This year has seen some groundbreaking and fascinating work in the field of hangover research, with scientists investigating the contribution of our DNA to the experience of alcohol-related hangover. This might help us understand why some people are more prone to hangovers, while others seem to “dodge a bullet” when it comes down to feeling rough the morning after the night before.
Much research has examined the influence of our inherited biology on alcohol intoxication, and our risk for alcohol misuse. Genes interact with environmental factors (things like peer alcohol use, or alcohol availability) to influence how much we drink, and our susceptibility to becoming dependent on alcohol. This year saw the publication of the first studies to tackle genetic influences on hangover, and there were some surprising findings.
Two studies investigated this in pairs of twins, a popular method for unravelling the contribution of genetic and environmental factors to a given behaviour. Differences in identical twins’ hangover experiences are compared with those of non-identical twins. Since the identical twins share all of their genes and the non-identical twins share around only 50% of their genes, any differences observed in variation of hangover experience in the identical twins are assumed to be the result of genes rather than environment.
Is hangover horror inherited?
The first study examined data collected in 1972 from 13,511 male second world war veteran twins. The twins were asked questions about their drinking in the past year to determine experience of hangover, such as “How often do you become really intoxicated?” and “How often do you have a hangover?”. The researchers found that the heritability of alcohol intoxication was around 50%, and for hangover was 55%. These findings suggest that experience of hangovers is substantially influenced by genes, with unshared environmental factors (eg access to alcohol) accounting for the rest of the variation.
However, there are some things to consider in the interpretation of these results. Participants were asked to report their alcohol intoxication and hangover experience for the past year. It is difficult to imagine that anyone would be able to accurately remember all of the occasions on which they had been drunk or hungover over the past 12 months. The present study also only recruited white males and therefore the results may not generalise to women or other ethnic groups. Additionally, the paper does not examine the influence of other factors that may impact on alcohol intoxication and hangover, eg existing illness (participants were middle aged at the time of testing), experience of stress, any other drug use (such as nicotine).
More generally, hangover researchers have yet to agree on a definitive measure of hangover. Recent research has identified biological markers related to the experience of hangover that can be tested using a urine sample, though analysis of these samples can be expensive and time consuming.
Can our genes determine hangover frequency and vulnerability?
A second study examined genetic influences on several measures of alcohol hangover (frequency, resistance and susceptibility) in 4,496 male and female twins. Results indicated that genetic factors accounted for 45% of the difference in hangover frequency (how many days in the past year you did not feel well the day after drinking) in males and 40% in females, in line with the previous study.
Interestingly, this study further shows that the heritability of hangover resistance (having no hangover the morning after being drunk) is around 43%, regardless of gender. This suggests that our genes may contribute to our ability to drink alcohol without falling victim to a terrible hangover. This is an important finding given that individuals who show a reduced response to alcohol intoxication (they need more alcohol to get drunk) may be at greater risk for alcohol dependency. Resistance to hangover may also be an important indicator of increased risk.
As with the other study, this research relied on self-reported measures of hangover over the past year and the accuracy of this type of assessment is questionable. Additionally, the authors were not able to measure other factors which may influence experience of hangover, such as how they respond to alcohol (how many drinks it takes to feel drunk) and whether they are unable to control their drinking.
Together these studies suggest that our likelihood of experiencing a hangover after a night of drinking is partly genetically influenced. Furthermore, the reason why some individuals can appear to drink endlessly and not wake up with a dreaded hangover while others cannot is also in part determined by our inherited biology.
These studies can’t identify specific genes contributing to our risk of getting a hangover, or reveal those that could determine who may be resistant to the “morning after” feeling. Future hangover research might focus on specific genes that have already been shown to influence alcohol use and dependency.
Before you go blaming your parents for that “blinder of a hangover”, it is worth remembering that these studies suggest that differences in our experiences of hangover are only half genetic and that environmental factors (which are currently less well understood) also play an important role.
Dr Sally Adams is a lecturer in health psychology at the University of Bath. Her research examines the cognitive and behavioural mechanisms underlying alcohol and tobacco use. Find her on Twitter @SallyScientist
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