New study test the effect of alcohol on sense of agency

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New research by neuroscientists from the University of Sussex shows that drinking only one pint of beer or large glass of wine is enough to significantly compromise a person’s sense of agency.

Sense of agency is the feeling of being in control of our actions.

It is an important aspect of human social behaviour, as it implies knowledge of the consequences of those actions.

This new study, Effect of alcohol on the sense of agency in healthy humans, is the first to test the effect of alcohol on the sense of agency.

The study focused on low doses of alcohol, typically consumed during social drinking, that do not produce a large impairment of behaviour.

Until now, research has mostly focused on the loss of inhibitory control produced by obvious drunkenness, characterised by impulsivity, aggression, and risky behaviour.

Dr Silvana De Pirro, lead author of the research paper, said: “Our study presents a compelling case that even one pint of beer is enough to significantly compromise a person’s sense of agency.

This has important implications for legal and social responsibility of drivers, and begs the question: are current alcohol limits for driving truly safe?”

Explaining how the study was conducted, Dr De Pirro said:

“Measuring a person’s sense of agency is tricky.

When people are explicitly asked to tell how in control they feel, their answers are affected by several cognitive biases, such as poor introspection, the desire to conform to researchers’ expectations, or even the inability to understand the question correctly.”

Sussex researchers relied therefore on an indirect measure called ‘intentional binding’, which has been developed to investigate the unconscious mechanisms of ‘volition’.

When physical stimuli (such as sounds or lights) follow voluntary actions (such as moving a finger or a hand), people judge actions as occurring later and stimuli as occurring earlier than in reality, hence ‘binding’ the two.

The neural mechanisms responsible for this phenomenon are thought to participate in creating the sense of agency.

This shows a beer tap in a bar

Even one pint of beer can compromise driving safety The image in the public domain.

In the experiments, subjects drank a cocktail containing doses of alcohol proportional to their BMI to produce blood alcohol concentrations within the legal limits for driving in England and Wales.

These doses of alcohol, corresponding to one or two pints of beer, produced tighter binding between voluntary actions and sensory stimuli.

This suggests that small amounts of alcohol might exaggerate the sense of agency, leading to overconfidence in one’s driving ability and to inappropriate, potentially dangerous behaviour.

Professor Aldo Badiani, Director of the Sussex Addiction Research and Intervention Centre (SARIC), said:

“It’s important to note that in our experiments, all the participants stayed within the legal alcohol limit for driving in England, Wales, the US and Canada. And yet we still saw an impairment in their feeling of being in control.

“In England, Wales and North-America, the argument to lower the limit has much momentum. The results of our study support the implementation of such a change in the law.”

The legal limit for driving in England and Wales is currently 80 mg/100 ml. The legal limit for driving in Scotland and most European countries is 50 mg/100 ml.

The study, Effect of alcohol on the sense of agency in healthy human, published in Addiction Biologytoday Friday 21 June, was the result of a collaboration of the Sussex Addiction Research and Intervention Centre, Sussex Neuroscience and the Sackler Centre for Consciousness Science at the University of Sussex, with the Department of Physiology and Pharmacology at the Sapienza University of Rome, Italy.


Throughout the 10,000 or so years that humans have been drinking fermented beverages, they’ve also been arguing about their merits and demerits.

The debate still simmers today, with a lively back-and-forth over whether alcohol is good for you or bad for you.

It’s safe to say that alcohol is both a tonic and a poison.

The difference lies mostly in the dose. Moderate drinking seems to be good for the heart and circulatory system, and probably protects against type 2 diabetes and gallstones. Heavy drinking is a major cause of preventable death in most countries.

In the U.S., alcohol is implicated in about half of fatal traffic accidents. [1]

Heavy drinking can damage the liver and heart, harm an unborn child, increase the chances of developing breast and some other cancers, contribute to depression and violence, and interfere with relationships.

Alcohol’s two-faced nature shouldn’t come as a surprise.

The active ingredient in alcoholic beverages, a simple molecule called ethanol, affects the body in many different ways.

It directly influences the stomach, brain, heart, gallbladder, and liver. It affects levels of lipids (cholesterol and triglycerides) and insulin in the blood, as well as inflammation and coagulation.

It also alters mood, concentration, and coordination.

What’s Moderate Alcohol Intake? What’s a Drink?

Loose use of the terms “moderate” and “a drink” has fueled some of the ongoing debate about alcohol’s impact on health.

In some studies, the term “moderate drinking” refers to less than 1 drink per day, while in others it means 3-4 drinks per day.

Exactly what constitutes “a drink” is also fairly fluid. In fact, even among alcohol researchers, there’s no universally accepted standard drink definition. [2]

In the U.S., 1 drink is usually considered to be 12 ounces of beer, 5 ounces of wine, or 1½ ounces of spirits (hard liquor such as gin or whiskey). [3] Each delivers about 12 to 14 grams of alcohol on average, but there is a wider range now that microbrews and wine are being produced with higher alcohol content.

The definition of moderate drinking is something of a balancing act. Moderate drinking sits at the point at which the health benefits of alcohol clearly outweigh the risks.

The latest consensus places this point at no more than 1-2 drinks a day for men, and no more than 1 drink a day for women. This is the definition used by the U.S. Department of Agriculture and the Dietary Guidelines for Americans 2015-2020, [3] and is widely used in the United States.

The Dark Side of Alcohol

Not everyone who likes to drink alcohol stops at just one. While many people drink in moderation, some don’t.

Heavy drinking can take a toll on the body. It can cause inflammation of the liver (alcoholic hepatitis) and lead to scarring of the liver (cirrhosis), a potentially fatal disease. It can increase blood pressure and damage heart muscle (cardiomyopathy).

Heavy alcohol use has also been linked with several cancers:

The World Cancer Research Fund and American Institute for Cancer Research indicate that there is convincing evidence linking alcohol to cancers of the mouth, pharynx, larynx, esophagus, breast, liver, colon, and rectum. [4]

The International Agency for Research on Cancer concluded that both the ethanol in alcohol and acetaldehyde, a chemical formed from the breakdown of ethanol, are carcinogenic to humans in high amounts. [5] The risk is multiplied for drinkers who also smoke tobacco or have a poor diet.

Problem drinking also touches drinkers’ families, friends, and communities. According to the National Institute on Alcohol Abuse and Alcoholism and others:

  • In 2014, about 61 million Americans were classified as binge alcohol users (5 or more drinks on the same occasion at least once a month) and 16 million as heavy alcohol users (5 or more drinks on the same occasion on 5 or more days in one month). [6]
  • Alcohol plays a role in one in three cases of violent crime. [7]
  • In 2015, more than 10,000 people died in automobile accidents in which alcohol was involved. [8]
  • Alcohol abuse costs about $249 billion a year. [9]

Even moderate drinking carries some risks. Alcohol can disrupt sleep and one’s better judgment. Alcohol interacts in potentially dangerous ways with a variety of medications, including acetaminophen, antidepressants, anticonvulsants, painkillers, and sedatives. It is also addictive, especially for people with a family history of alcoholism.

Alcohol Increases Risk of Developing Breast Cancer

There is convincing evidence that alcohol consumption increases the risk of breast cancer, and the more alcohol consumed, the greater the risk. [10-14]

  • A large prospective study following 88,084 women and 47,881 men for 30 years found that even 1 drink a day increased the risk of alcohol-related cancers (colorectum, female breast, oral cavity, pharynx, larynx, liver, esophagus) in women, but mainly breast cancer, among both smokers and nonsmokers. 1 to 2 drinks a day in men who did not smoke was not associated with an increased risk of alcohol-related cancers. [15]
  • In a combined analysis of six large prospective studies involving more than 320,000 women, researchers found that having 2-5 drinks a day compared with no drinks increased the chances of developing breast cancer as high as 41%. It did not matter whether the form of alcohol was wine, beer, or hard liquor. [10] This doesn’t mean that 40% or so of women who have 2-5 drinks a day will get breast cancer. Instead, it is the difference between about 13 of every 100 women developing breast cancer during their lifetime—the current average risk in the U.S.—and 17 to 18 of every 100 women developing the disease. This modest increase would translate to significantly more women with breast cancer each year.

A lack of folate in the diet or folic acid, its supplement form, further increases the risk of breast cancer in women. [14] Folate is needed to produce new cells and to prevent changes in DNA. Folate deficiency, as can occur with heavy alcohol use, can cause changes in genes that may lead to cancer. Alcohol also increases estrogen levels, which fuel the growth of certain breast cancer cells. An adequate intake of folate, at least 400 micrograms a day, when taking at least 1 drink of alcohol daily appears to lessen this increased risk. [16, 17]

  • Researchers found a strong association among three factors—genetics, folate intake, and alcohol—in a cohort from the Nurses’ Health Study II of 2866 young women with an average age of 36 who were diagnosed with invasive breast cancer. Those with a family history of breast cancer who drank 10 grams or more of alcoholic beverages daily (equivalent to 1 or more drinks) and ate less than 400 micrograms of folate daily almost doubled their risk (1.8 times) of developing the cancer. Women who drank this amount of alcohol but did not have a family history of breast cancer and ate at least 400 micrograms of folate daily did not have an increased breast cancer risk. [14]

Alcohol and Weight Gain

One serving of alcohol on average contains 100-150 calories, so even a moderate amount of 3 drinks a day can contribute 300+ calories. Mixed drinks that add juice, tonic, or syrups will further drive up calories, increasing the risk of weight gain over time.

However, a prospective study following almost 15,000 men at four-year periods found only an increased risk of minor weight gain with higher intakes of alcohol. [19] Compared to those who did not change their alcohol intake, those who increased their intake by 2 or more drinks a day gained a little more than a half-pound. It was noted that calorie intake (not from alcohol) tended to increase along with alcohol intake.

Possible Health Benefits of Alcohol

What are some of the possible health benefits associated with moderate alcohol consumption?

Cardiovascular Disease

More than 100 prospective studies show an inverse association between light to moderate drinking and risk of heart attack, ischemic (clot-caused) stroke, peripheral vascular disease, sudden cardiac death, and death from all cardiovascular causes. [20] The effect is fairly consistent, corresponding to a 25-40% reduction in risk. However, increasing alcohol intake to more than 4 drinks a day can increase the risk of hypertension, abnormal heart rhythms, stroke, heart attack, and death. [5, 21-23]

The connection between moderate drinking and lower risk of cardiovascular disease has been observed in men and women. It applies to people who do not have heart disease, and also to those at high risk for having a heart attack or stroke or dying of cardiovascular disease, including those with type 2 diabetes, [32, 33] high blood pressure, [34, 35] and existing cardiovascular disease. [34, 35] The benefits also extend to older individuals. [36]

The idea that moderate drinking protects against cardiovascular disease makes sense biologically and scientifically. Moderate amounts of alcohol raise levels of high-density lipoprotein (HDL, or “good” cholesterol), [37] and higher HDL levels are associated with greater protection against heart disease. Moderate alcohol consumption has also been linked with beneficial changes ranging from better sensitivity to insulin to improvements in factors that influence blood clotting, such as tissue type plasminogen activator, fibrinogen, clotting factor VII, and von Willebrand factor. [37] Such changes would tend to prevent the formation of small blood clots that can block arteries in the heart, neck, and brain, the ultimate cause of many heart attacks and the most common kind of stroke.

Drinking Patterns Matter

What you drink (beer or wine) doesn’t seem to be nearly as important as how you drink. Having 7 drinks on a Saturday night and then not drinking the rest of the week isn’t at all the equivalent of having 1 drink a day.

The weekly total may be the same, but the health implications aren’t. Among participants in the Health Professionals Follow-up Study, consumption of alcohol on at least three or four days a week was inversely associated with the risk for myocardial infarction.

The amount consumed, under 10 grams a day or more than 30 grams, didn’t seem to matter as much as the regularity of consumption. [25] A similar pattern was seen in Danish men. [38]

A review of alcohol consumption in women from the Nurses’ Health Study I and II found that smaller amounts of alcohol (about 1 drink per day) spread out over four or more days per week had the lowest death rates from any cause, compared with women who drank the same amount of alcohol but in one or two days. [39]

The most definitive way to investigate the effect of alcohol on cardiovascular disease would be with a large trial in which some volunteers were randomly assigned to have 1 or more alcoholic drinks a day and others had drinks that looked, tasted, and smelled like alcohol but were actually alcohol free.

Many of these trials have been conducted for weeks, and in a few cases months and even up to 2 years, to look at changes in the blood, but a long-term trial to test experimentally the effects of alcohol on cardiovascular disease has not been done. 

A recent successful effort in the U.S. to launch an international study was funded by the National Institutes of Health.  Although the proposal was peer-reviewed and initial participants had been randomized to drink in moderation or to abstain, post hoc the NIH decided to stop the trial due to internal policy concerns.  

Unfortunately, a future long trial of alcohol and clinical outcomes may never be attempted again, but nevertheless, the connection between moderate drinking and cardiovascular disease almost certainly represents a cause-and-effect relationship based on all of the available evidence to date.

Beyond the Heart

The benefits of moderate drinking aren’t limited to the heart. In the Nurses’ Health Study, the Health Professionals Follow-up Study, and other studies, gallstones [40, 41] and type 2 diabetes [32, 42, 43] were less likely to occur in moderate drinkers than in non-drinkers. The emphasis here, as elsewhere, is on moderate drinking.

In a meta-analysis of 15 original prospective cohort studies that followed 369,862 participants for an average of 12 years, a 30% reduced risk of type 2 diabetes was found with moderate drinking (0.5-4 drinks a day), but no protective effect was found in those drinking either less or more than that amount. [32]

The social and psychological benefits of alcohol can’t be ignored. A drink before a meal can improve digestion or offer a soothing respite at the end of a stressful day; the occasional drink with friends can be a social tonic. These physical and social effects may also contribute to health and well-being.


Source:
University of Sussex
Media Contacts: 
Anna Ford – University of Sussex
Image Source:
The image is in the public domain.

Original Research: Closed access
“Effect of alcohol on the sense of agency in healthy humans”. Silvana De Pirro, Peter Lush, Jim Parkinson, Theodora Duka, Hugo D. Critchley, Aldo Badiani.
Addiction Biology. doi:10.1111/adb.12796

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