Alcohol and caffeine

We sometimes hear that we should be drinking red wine or coffee to protect our thinking skills in later life. But should we? Dr Janie Corley at the University of Edinburgh, as part of our Staying Sharp series, weighs up the evidence.

Alcohol - does it protect thinking skills as we age?

Researchers who study the effect of lifestyle factors on the way our thinking skills change as we age are often asked whether alcohol has an influence. 

A number of research groups in different countries have studied this question. A summary of their findings published in 2014 showed that drinking light to moderate amounts of alcohol is associated with better thinking skills in older people than not drinking or heavy drinking. There is also some evidence that such a level of alcohol intake might help protect us against age-related cognitive decline.

But we should be cautious too. Alcohol affects other aspects of health and so it is best to stick to Government alcohol consumption guidelines because they take those other aspects into account. In the UK, current guidelines advise no more than 14 units of alcohol a week. There is more information in the ‘Alcohol advice’ box below.

Further, various studies have found that very heavy drinking increases the risk of dementia. It results in the loss of brain tissue, particularly in areas of the brain related to memory and identifying shapes and distance between objects.

What's the explanation?

The potential benefits of the occasional tipple for thinking skills such as memory, speed of information processing and reasoning may be partly due to a reduction in the risk of cardiovascular disease (conditions of the heart and blood vessels such as coronary heart disease, stroke and aortic disease). Alcohol increases blood flow to the brain, reduces inflammation and can help improve cholesterol levels.

However, there may be other explanations of the benefits of alcohol. For instance, moderate alcohol intake is associated with a healthier lifestyle, existing good health and more social engagement, which are themselves associated with better thinking skills in later life.

A more complex picture is suggested by results of our studies with the Lothian Birth Cohort 1936 (the people participating in the Age UK-funded Disconnected Mind project).

We found that people with a higher IQ in youth were more likely to drink moderately as adults (equivalent to around 1-2 glasses of wine per day). So it may be that having better thinking skills in later life is not down to drinking alcohol, but to having better thinking skills to start with in childhood. In other words, it may be that lifetime cognitive function influences alcohol consumption habits rather than vice versa.

Some studies suggest a particularly beneficial effect of red wine (again, in modest amounts) on thinking skills. One explanation for these results may lie in the antioxidant effects of flavonoids that are present in wine, but absent in other forms of alcohol (flavonoids are chemical substances found in many plants, including fruit).

Weighing up the evidence

To date, the evidence is not strong enough to suggest that people who do not drink should start drinking. This is especially true when weighed against the potential negative effects of excessive alcohol consumption in older people, such as increased risk of falls, vascular disease, cognitive decline and dementia.

Overall, when it comes to alcohol, stick to Government guidelines.

How does caffeine affect us?

Caffeine, a chemical compound found in coffee, tea, cola and some foods including chocolate, stimulates the central nervous system and has many positive actions on the brain. 

In the short term, it can increase alertness, help concentration, reduce reaction time and improve mood. Many people drink coffee to ease feelings of fatigue and maintain alertness when sleep-deprived.

Does caffeine protect thinking skills as we age?

This picture is less clear. A recent review of the results of a range of studies conducted in the USA, Europe, Asia, Australia and elsewhere looked at the association between caffeine intake from the diet and cognitive function in later life. The review concluded that there was some limited positive association.

The most consistent associations with better cognitive function in older people were when the caffeine came from coffee, and the effect was more marked in women than men.

Research has also indicated that the risk of cognitive decline and cognitive disorders such as dementia appears to be lowest for those people drinking 1-2 cups of coffee per day.

However, the research to date is limited and the effects that are seen are relatively small.

What’s the explanation?

As for alcohol, these results may be explained by other factors, rather than the caffeine itself.

For example, caffeine intake is strongly related to IQ and social class. In our studies with the Lothian Birth Cohort 1936, the members of the cohort who had better thinking skills as children tended to have better thinking skills at age 70 and they also drank more caffeine, especially in the form of coffee. They also had healthier lifestyles in general.

So it might be the better thinking skills throughout their lives, and/or better health, that is helping protect their thinking skills in older age, rather than the caffeine.

Weighing up the evidence

There is more that we need to find out. Important issues for further research are whether caffeine has a truly independent protective effect on our thinking skills as we age, what forms of caffeine are effective, how much should be taken, and what are the differences in the effect between genders.

In the meantime, current evidence says that coffee does not present harmful effects for the brain if it is consumed at levels of up to 300-400mg daily (4-5 cups of coffee).

However, it’s important to remember that caffeine has many effects on the body as well as in the brain, not all positive – for example it can disturb sleep and raise anxiety.

Also, we differ in our sensitivity and reaction to caffeine, so that amount of caffeine a day might not be suitable for everyone.

Key references

• Beydoun, M. A., Beydoun, H. A., Gamaldo, A. A., Teel, A., Zonderman, A. B. and Wang, Y., 2014. Epidemiologic studies of modifiable factors associated with cognition and dementia: systematic review and meta-analysis. BMC public health, 14(1), p.643.
• Corley, J., Jia, X., Brett, C. E., Gow, A. J., Starr, J. M., Kyle, J. A., McNeill, G. and Deary, I. J., 2011. Alcohol intake and cognitive abilities in old age: The Lothian Birth Cohort 1936 study. Neuropsychology, 25(2), p.166.
• Corley, J., Jia, X., Kyle, J. A., Gow, A. J., Brett, C. E., Starr, J. M., McNeill, G. and Deary, I. J., 2010. Caffeine consumption and cognitive function at age 70: the Lothian Birth Cohort 1936 study. Psychosomatic medicine, 72(2), pp.206-214.
• Nehlig, A., 2015. Effects of coffee/caffeine on brain health and disease: What should I tell my patients?. Practical neurology, pp.practneurol-2015.
• UK Chief Medical Officers’ Low Risk Drinking Guidelines. Department of Health. August 2016.
• Wu, L. D., & He, Y., 2016. Coffee intake and the incident risk of cognitive disorders: A dose-response met-analysis of nine prospective cohort studies. Clinical Nutrition. 
• Prince, M. J., 2014. World Alzheimer Report 2014: dementia and risk reduction: an analysis of protective and modifiable factors.