Monday 22 August 2016

Booze and brains: does alcohol really kill brain cells?

image via shutterstock.com

Whether we like to admit it or not, most of us are guilty of having had a little bit too much to drink at one time or another. You might have drowned your sorrows and stress after a hard week at work, or been caught up in celebrations and indulged in a few too many at a wedding. Or maybe, it was by complete accident that you suddenly found yourself lit up like a Christmas tree, and arrived at work on Monday morning claiming fewer brain cells than you went home with on Friday afternoon.

But what do we actually know about the effects of alcohol on the brain? Does it really ‘kill’ our brain cells, or is it a little more complicated than that?

The physiology
Alcohol is a central nervous system depressant. In other words, it has a ‘slowing down’ effect on brain function. This might seem a little strange; alcohol is commonly seen as a ‘pick-me-up’, because in the initial stages of consumption, we become more animated and less reserved. However, the opposite of this occurs when we continue to drink and more alcohol enters the brain.

In the brain, alcohol easily crosses the blood-brain barrier, an important membrane separating the blood from the fluid surrounding our brains. The purpose of the blood-brain barrier is to protect the brain from harmful substances. When it crosses this barrier, alcohol directly affects our neurotransmitters and receptors of neurons, and therefore interrupts the successful transmission of signals from the brain to the body, and the body to the brain.

Our neurotransmitters (NTs) can either be excitatory (causing an increase in activity) or inhibitory (causing a decrease in activity). Alcohol promotes the effects of our inhibitory NTs, while simultaneously reducing the effects of our excitatory NTs; hence its depressant effect on our nervous system. Alcohol also increases the amount of dopamine (one of our ‘feel-good’ chemicals) in the brain’s reward system, creating the feeling of pleasure that occurs when we drink.

image via shutterstock.com

Binge drinking and the brain
The short-term effects of alcohol consumption are well known, and have likely been experienced by many of us. A pattern of drinking is considered ‘binge drinking’ after 4 or more drinks are consumed on one occasion for women, and 5 or more drinks for men. But what's actually happening in the brain after we've thrown back those four or five drinks?

Slowed reaction times, lowered inhibitions, difficulty concentrating, slurred speech; these commonly experienced side effects of alcohol consumption are a direct result of misfiring brain signals being unable to get from A to B as easily as they should. Alcohol simply reduces the efficiency and effectiveness of the brain signals that allow us to function normally, both physically and mentally.

Ever wondered why memories of the night before are never quite as good as we hope they would be? That’s because when we drown our cells in alcohol, our poor hippocampi can’t do their thing and consolidate these memories while we sleep.

While sessions of binge drinking in the short-term don’t necessarily ‘kill’ our brain cells, they certainly get in the way of our brain’s ability to function optimally.

Long-term use or abuse
We know that many of the immediate effects of alcohol consumption resolve when we sober up. However, when a person drinks heavily over a prolonged period of time, some of these impairments may persist long after sobriety is achieved.

Long-term drinking can lead to brain atrophy (shrinkage), and permanent damage of the fibres that transmit signals and carry information from one neuron to the next. Many long-term alcoholics also develop a neuropsychological condition called Wernicke-Korsakoff Syndrome (WKS), which is caused by a thiamin deficiency (a B vitamin). People with WKS experience vision changes (nystagmus), problems with walking and coordination (ataxia), and significant cognitive disturbance (dementia). Fortunately, some of the acute symptoms of WKS can resolve when an individual’s thiamin returns to a healthy level.

via giphy.com

The hungover brain
Dehydration is the known culprit for that shocking hangover we’ve all woken up with. But what many don’t know is that our brains are actually to blame for causing this dehydration in the first place.

When alcohol crosses the blood brain barrier, it causes our pituitary gland to block the creation of vasopressin, the antidiuretic hormone. Without vasopressin, the brain tells the kidneys to send water directly to the bladder without letting it reabsorb back into the body. And that headache we all know and dread? That’s our organs making up for their lack of water by stealing water from the brain. This causes our brains to shrink a little, and pull on the membranes connecting the brain to the skull. Hello headache!

Are our brain cells safe?
The odd night out drinking or accidental over-indulging in the alcohol stakes aren’t quite enough to ‘kill’ our precious brain cells. However, long-term serious alcohol use (or addiction) can certainly lead to permanent damage to the cells in our brain, and associated physical and neuropsychological symptoms.

The important thing to remember is everything in moderation, and for the sake of future you, doing everything possible to prevent or alleviate that hangover when you have indulged. Drink plenty of water throughout the night (and the following day) to replenish the water lost in the brain and the body, and there’s certainly no harm in downing some vegemite toast before bedtime if you’re worried about those thiamin levels. 

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