Hangover nation: What is it about Ireland and drink?

At the start of European Month of the Brain, Shane O’Mara says the effects of excessive alcohol consumption on one of our vital organs should not be underestimated

We drink too much in Ireland. As a nation, we consistently place highly in the global heavy drinking league. Excess alcohol consumption causes many problems. It is, for example, the major cause of death in men aged 35 to 50 in Ireland. A HSE report suggests the estimated overall cost of alcohol abuse to Irish society was €3.7bn in 2007. The consequences of long-term, heavy drinking are by now well-known within the health services and to health professionals, if not often well understood by the drinking public at large. Every organ system and tissue of the body is adversely affected by alcohol misuse. The effects of alcohol misuse can be amplified by consuming tobacco and other drugs. There may also be particular genetic vulnerabilities to alcohol which also amplify its effects.

The consequences of long-term heavy drinking for the brain are becoming better understood. Alcohol depresses brain function, circuit by circuit, causing reliable, characteristic, and sought-after effects. Alcohol consumption causes behavioural changes, starting with feelings of euphoria and loss of inhibitions. Continued alcohol consumption impairs thinking (including understanding the thoughts and intentions of others), and impairs motor function. With enough alcohol is consumed, the brain circuits controlling vital for life functions, such as breathing (inducing “respiratory depression”), become impaired. This may result in possible brain damage and even brain death. A sustained reduction in alcohol consumption (or abstaining from alcohol) can halt or even reverse damage to many, if not most body tissues and organs.

The brain changes constantly during life. This is referred to as brain plasticity or neuroplasticity. The brain changes and modifies its structure and organisation during normal development and maturation, as well as a result of experience. The brain is altered by many things (including sensory and motor experience, hormones, drugs, ageing, stress, diet, learning, and other factors).

A key regulator of brain plasticity is how the brain responds to rewards. Dopamine is the primary neurotransmitter in the reward pathways of the brain. Drugs of abuse act to increase dopamine levels in the brain’s reward pathways. Addicts, including alcoholics, display characteristic behavioural changes sometimes called the ‘3Cs’. These ‘Cs’ are the compulsion to use the drug; the inability or incapacity to control use of the drug; and continued use of the drug, despite the consequences of the drug use. These changes in behaviour provide an important clue in the search to understand what alcohol abuse does to the brain.

We know from brain imaging studies of alcoholics and non-alcoholics that consuming alcohol increases the neurotransmitter dopamine in the brain’s reward system — which is felt as pleasurable and rewarding. This is something alcohol shares with all drugs of abuse. Sustained drug abuse usually results in a reduction of dopamine in the brain’s reward circuits — resulting in the need for more of the drug to get the same effect on dopamine levels in the brain’s reward circuits. Brain imaging studies show that chronic alcoholics have a deficiency in the release of dopamine in the brain’s reward system. Normal levels of dopamine are not present, and the drug (in this case, alcohol) is needed to stimulate the release of dopamine in the reward circuits. Hence the craving and drug-seeking that occurs in alcoholism. A reasonable conclusion, therefore, is that long-term alcohol abuse modifies brain neurotransmitter systems and especially those associated with experiencing pleasure and reward. In other words, the brain changes because of long-term exposure to heavy drinking — an example of neuroplasticity in action.

Long-term, follow-up studies on teenage drinking conducted in the US show early drinking (especially between the ages of about 12 to 14) is associated with a dramatic increase in the risk of alcoholism in later life. In other words, the great wave of hormone-related neuroplasticity that occurs during adolescence interacts with alcohol with worrying long-term consequences. This puts the adolescent at a much greater risk of developing alcoholism in later life.

Delaying drinking for as long as possible in the teenage years should be a public health priority. Happily, the latest data show that the proportion of children reporting never having had an alcoholic drink has increased (from about 40% in 2002 to 54% in 2010). Worryingly, however, about 25% of children in Ireland aged 15 self-report as having been drunk at least once in the last 30 days.

A consensus exists in addiction research that “addiction is a brain disease and it matters”, as Alan Leshner, an eminent addiction neuroscientist, has put it. Alcohol dependence may be regarded as a brain disease: One resulting from the modification (by long-term heavy alcohol exposure) of the circuits in the brain associated with reward, memory and behavioural control. To quote Leshner, this makes addiction a “chronic, relapsing brain disorder characterised by compulsive drug seeking”.

However, alcohol addiction is a disease which is being increasingly understood. Alcoholism arises as a result of the interaction between the sustained and heavy consumption of alcohol and the brain — inducing extensive plastic changes in that brain as a result. It is, therefore, an addiction which should be increasingly possible to treat by focusing on these plastic changes in the brain — whether by drug treatment, environmental, cognitive and behavioural changes, or some combination of these factors.

*Shane M O’Mara, Professor of Experimental Brain Research, isdirector of Trinity College Institute of Neuroscience


Who hasn’t dreamt of cutting ties with the nine-to-five and living off-the-grid?The great escape: What's life like off the grid?

Jazz in Europe these days exists in a highly networked environment of cultural and political bodies, festivals, promoters, musicians and educators.Jazz Connective Festival: Intriguing, exciting and uncompromising

It will be bittersweet for Stormzy that his second album arrives the day the British Labour party was confirmed as suffering a historic general election trouncing.Album review: Stormzy remains a work in progress

Unique drawings by Quentin Blake, one of Britain’s best-loved illustrators, are available at a Christie’s online auction which runs until December 17.Your chance to buy drawings by Roald Dahl illustrator Quentin Blake

More From The Irish Examiner