Binge drinking as a teenager can damage the brain for LIFE: Alcohol triggers changes to the regions affecting memory and learning

  • Alcohol exposure in adolescence can cause enduring abnormalities 
  • Can have detrimental effect on a person's memory and ability to learn
  • And scientists warn binge drinking could also slow emotional maturity 

By Lizzie Parry for MailOnline

Published: 11:03 EST, 27 April 2015 | Updated: 17:49 EST, 27 April 2015

Teenagers who regularly drink alcohol could be doing irreparable damage to the parts of the brain that controls memory and learning, scientists warn

Teenagers who regularly drink alcohol could be doing irreparable damage to the parts of the brain that controls memory and learning, scientists warn

Binge drinking as a teenager causes long-lasting changes to the regions of the brain that control learning and memory.

A new study has shown that alcohol exposure during adolescence, before the brain is fully developed, can result in abnormalities that have enduring, detrimental effects on a person's behaviour.

And scientists warn alcohol could also slow down emotional maturity.

Dr Mary-Louise Risher, at Duke University, said: 'In the eyes of the law, once people reach the age of 18, they are considered adult.

'But the brain continues to mature and refine all the way into the mid 20s.

'It's important for young people to know that when they drink heavily during this period of development, there could be changes occurring that have a lasting impact on memory and other cognitive functions.'

Researchers periodically exposed young rodents to a level of alcohol during adolescence that, in humans, would result in impairment, but not sedation.

Afterwards, the animals received no further exposure to alcohol, and grew into adulthood, which in rats occurred within 24 to 29 days. 

Past research has shown that adolescent animals exposed to alcohol grow into adults that are much less adept at memory tasks than normal animals - even with no further alcohol exposure.

But until now, scientists have not known how these impairments manifest in the hippocampus - the part of the brain responsible for memory and learning.

Using small electrical stimuli applied to the hippocampus, researchers were able to measure a cellular mechanism, called long-term potentiation, or LTP.

This is the strengthening of brain synapses - the connections between brain cells, or neurons - as they become used to learning new tasks or recalling memories.

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Learning occurs best when this synaptic activity is vigorous enough to build strong signal transmissions between neurons.

LTP is highest in the young, and effective learning is crucial for teenagers to acquire large amounts of new memory during the transition to adulthood.

It's important for young people to know that when they drink heavily, there could be changes occurring that have a lasting impact on memory
Dr Mary-Louise Risher, at Duke University

The researchers said they expected to find abnormally diminished LTP in the adult rats that had been exposed to alcohol during their adolescence.

Surprisingly, though, LTP was actually hyperactive in these animals compared to the unexposed rodents.

'At first blush, you would think the animals would be smarter,' said Professor Scott Swartzwelder.

'But that's the opposite of what we found. 

'And it actually does make sense, because if you produce too much LTP in one of these circuits, there is a period where you can't produce any more.

'The circuit is saturated, and the animal stops learning.

'For learning to be efficient, your brain needs a delicate balance of excitation and inhibition - too much in either direction and the circuits do not work optimally.' 

Importantly, Professor Swartzwelder, Dr Risher and their colleagues identified that the LTP abnormality was accompanied by a structural change in individual nerve cells. 

The hippocampus, highlighted in red, is the part of the brain that controls memory and learning. Researchers at Duke University discovered how these impairments manifest themselves in the hippocampus

The hippocampus, highlighted in red, is the part of the brain that controls memory and learning. Researchers at Duke University discovered how these impairments manifest themselves in the hippocampus

The tiny protrusions from the branches of the cells, called dendritic spines, appeared lanky and spindly, suggesting immaturity.

Mature spines are shorter and look a bit like mushrooms, refining cell-to-cell communication. 

Professor Swartzwelder, added: 'Something happens during adolescent alcohol exposure that changes the way the hippocampus and other regions of the brain function and how the cells actually look - both the LTP and the dendritic spines have an immature appearance in adulthood.'

Dr Risher said this immature quality of the brain cells might be associated with behavioural immaturity.

'It's quite possible that alcohol disrupts the maturation process, which can affect these cognitive function later on,' she said.

'That's something we are eager to explore in ongoing studies.' 

The study was published today in the journal Alcoholism: Clinical and Experimental Research.  

 

  

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