A bump on the head as a child increases the risk of ALCOHOLISM in later life

Girls who suffer concussion in childhood could be at heightened risk of alcohol addiction, experts have warned.

Females who suffered a mild closed-head brain injury were more likely to misuse alcohol, and associate drinking with reward and pleasure, a study found.

However, the same effect was not seen in males, researchers at Ohio State University noted. 

They believe the link is triggered by changes to nerve fibres in the brain, that occur after a concussion. 

They said although recording the increased risk in girls, the effect was reversible.

Experiments on mice found those living in an enriched environment, with more toys and exercise options after the injury than for mice living in standard conditions.

An enriched environment prevented increased drinking, and reduced degeneration of axons, the long, slender extensions of the nerve cell body.

The conditions were intended to mimic sustained follow-up care after a human brain injury, Dr Zachary Well, assistant professor of neuroscience at the university said.

'We wanted to demonstrate that this effect is not set in stone at the time of injury,' he said.

'There are always ways to intervene, but they're expensive in terms of effort and money.

'It requires sustained treatment and rehabilitation and educational support.

'The best therapy for a childhood brain injury is everybody getting great medical care and rehabilitation, regardless of socioeconomic status.

'People with juvenile head injuries are already at risk for memory problems, difficulty concentrating, poor learning and reduced impulse control.

'If we can prevent alcohol misuse, chances for a good life are much better.' 

Alcohol is already strongly linked to traumatic brain injuries. 

An estimated one third to half of concussion patients are drunk at the time they suffer their injury.

Dr Weil said: 'So what we hoped to determine was whether it is possible that if you had an injury as a juvenile, would you be more likely to drink heavily later on, which would put you at risk for having a more severe brain injury as an adult.

'There is some evidence that if you have a brain injury, you're more likely to drink.

'But nobody has looked at the time of the injury and nobody has looked at sex differences.' 

In order to arrive at their findings, Dr Weil and his team performed a series of experiments.

Mice received a concussive head injury at 21 days old, the equivalent of humans being six to 12 years old.

They were then allowed to choose between two bottles, one containing water and the other water mixed with doses of ethanol.

Female adult mice that had suffered a mild concussion drank significantly more ethanol than uninjured mice.

But the juvenile head injury appeared to have no effect on male mice.

Physiological tests suggested the injury had nothing to do with how the animals processed alcohol.

This prompted the research team to explore the potential theory that young injured female mice were drawn by reward sensations.

In this experiment, mice were placed in a box with visibly different patterns covering separate sections of the floor. 

Over 10 days, researchers injected them with alcohol in specific sections of the box and with saline in other sections. 

'Then we let them walk back and forth between boxes,' Dr Weil explained. 'If they liked alcohol, they would spend more time on the side of the box associated with alcohol.

'Again, we saw this effect only in females that had been injured.

'They spent about 65 per cent of their time in the box linked to alcohol.

'We had proven to ourselves that there is something about the way reward and pleasure is processed in these animals with regard to alcohol.'  

In studying the effects of enrichment, Dr Weil and colleagues put recently injured mice in bigger cages with running wheels, toys and tunnels, providing a new experience every week for six weeks. 

Control injured animals lived in standard housing conditions. 

When the mice were tested for alcohol intake, the enriched environment had completely blocked the females’ increase in drinking. 

The enriched environment also reduced axon damage in their brains by about 40 per cent.

The results for females are particularly concerning to researchers because two populations of traumatic brain injury patients are currently increasing: elderly adults and young women – 'not just athletes, but athletics is driving it,' Dr Weil said. 

'But there isn’t a lot of research on understanding how and why the injury effects are different between men and women.'

Dr Weil said he plans to follow up by studying whether hormones – not just which hormones, but when in life they’re most active – drive this difference in alcoholism risk between males and females with juvenile head injuries.  

The study is published in the Journal of Neurotrauma. 

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