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Author Topic: Does alcohol kill brain cells?  (Read 7023 times)

Offline Jennifer Jackson

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Does alcohol kill brain cells?
« on: 08/05/2010 22:30:04 »
Jennifer Jackson  asked the Naked Scientists:
Hi Chris and the Naked Scientists

I discovered newbielink: [nonactive] a few weeks ago while searching in desperation for some good scientific media reporting.

Your newbielink: [nonactive] is a really excellent example of that, and I've been listening avidly to your back catalogue and recommending your program to friends and colleagues ever since.

My good friend Gaby in New Zealand has become a fan too and we were wondering if there is any truth in the common statement that alcohol causes brain cell death, what the measurable effect is, and whether eating spicy food also does this, as we've heard claims along these lines.

Very best of luck and success in your work,

Jen and Gaby

What do you think?
« Last Edit: 08/05/2010 22:30:04 by _system »


Offline aaron28

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Does alcohol kill brain cells?
« Reply #1 on: 08/05/2010 22:36:29 »
In a sense yes, alcohol can kill brain cells. Being drunk is your brain's reaction to being suffocated. Alcohol replaces oxygen and produces the intoxication. Enough of it can kill you, in essence, killing a lot of brain cells.
« Last Edit: 08/05/2010 22:40:22 by aaron28 »

Offline Bored chemist

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Does alcohol kill brain cells?
« Reply #2 on: 09/05/2010 09:35:36 »
Alcohol doesn't replace oxygen.

Offline chris

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Does alcohol kill brain cells?
« Reply #3 on: 09/05/2010 12:09:12 »
Alcohol (ethanol) is a toxic chemical, but the body is metabolically well-equipped to deal with it, with the liver accounting for the majority of this detoxification. This organ is the first port of call for blood draining from the digestive tract before it enters the systemic circulation.

This means the liver has the opportunity to remove, catabolise or metabolise the products of digestion to prevent the tissues of the body being exposed to high concentrations of certain chemicals, like amino and organic acids and sugars, which, if they passed into circulation unchecked, could have deleterious effects.

This is known as "first pass" metabolism and means that the bulk of the alcohol we drink is removed before it gets near the systemic circulation. The small amount that does make it through partitions into the dependent tissues of the body, including the brain. Consequently, the bigger an individual's volume of distribution (i.e. how much body mass they have into which the alcohol can dissolve) the more alcohol they can take in without ill effect.

The brain is quite vulnerable to alcohol intake, however, because it has a high blood flow (i.e. capable of delivering large amounts of alcohol) and it contains a lot of lipid, which dissolves alcohol quite readily. This helps to maintain a good concetration gradient, drawing alcohol into the nervous system. The effect of the alcohol "wears off" through three mechanisms: i) as it is broken down by the liver and the concentration in the body falls, ii) as alcohol redistributes from the brain to other fatty tissues in the body and iii) as the brain adjusts its activity to compensate for the presence of the alcohol.

Alcohol affects the brain by sensitising nerve cells to the main inhibitory nerve transmitter, GABA. This damps down brain activity, which is why alcohol acts as a CNS depressant and, in overdose, causes sleepiness, unconsciousness and even coma or death. Effectively it behaves as an anaesthetic.

At the concentrations encountered normally, alcohol is therefore probably not overly toxic to neurones because it decreases their activity rather than over-exciting them like some drugs (such as ecstasy). The exception to this is in problem drinkers who, if they withdraw suddenly, can experience fits and seizures, which can be fatal - both for brain cells and for the whole patient.

This aside, there is no evidence for declining intellect amongst recreational (safe) drinkers, compared with teatotallers; in fact, the reverse may be true and there are papers showing an association between preserved intellect with age and low-level alcohol intake.

However, there are ways in which chronic sustained alcohol intake can be associated with brain damage. There is a condition called Wernicke-Korsakoff's syndrome, which is characterised by impaired movement and memory problems; sufferers cannot form new memories and also lose their existing memories causing them to "confabulate" - they make up stories to account for things that are happening to them.

This condition is often associated with alcoholism but, despite this association, is not caused by the alcohol directly but by accompanying malnutrition because most problem drinkers fail to eat properly. This causes a deficiency of vitamin B1 - thiamin - which is metabolically critical for the healthy function of cells, including neurones; without it the carboxylic acid cycle cannot function properly and so cells cannot make sufficient energy to sustain their needs and they die.

Therefore, in summary, it's probably not true when someone claims that every hangover costs you a million brain cells, but that's not to say that alcohol isn't toxic - if neurones were incubated in a sufficiently strong solution of alcohol they would die, but such concentrations are not normally encountered in the human body. Instead, alcohol is indirectly linked to brain injury, usually as a consequence of people falling over when drunk, getting into fights or through chronic abuse.

So chin up and let's get another round in; mine's a pint of Carling...
« Last Edit: 09/05/2010 12:11:27 by chris »

Offline thedoc

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« Last Edit: 01/01/1970 01:00:00 by _system »

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Does alcohol kill brain cells?
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