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Brain injury causes impulse control issues in rats: UBC study

The study could lead to better treatment options for head-trauma and addiction patients

A UBC study has found brain injury causes impulse control issues among rats.

Metro File

A UBC study has found brain injury causes impulse control issues among rats.

UBC researchers have found that even mild brain injury can cause impulse control issues in rats.

Rats with head trauma were unable to wait in order to receive a bigger reward, and instead opted for a small, immediate reward, the study found.

The rats’ lack of impulse control lasted throughout the eight-week experiment, indicating it could be a chronic symptom of head trauma, persisting even after memory and motor functions return.

“We saw that relatively mild brain injury can induce a long-term impulsive state,” said Cole Vonder Haar, lead author of the study.

Eight weeks is about a tenth of a rat’s lifetime, he explained.


His team tested the rats’ impulse control by offering them sugar pellets.

Rats could choose to either receive one sugar pellet now or four sugar pellets later. Those that had suffered brain injuries chose the single sugar pellet more often.

Researchers found that rats that were more likely to choose the single sugar pellet also more often also had higher levels of interleukin-12 in their brain tissue. That finding could be the missing link in explaining addictive behaviour in people who have suffer brain injuries.

“One of the things that has been most heavily linked to addiction is problems with impulse control,” said Vonder Haar.

“People are seeing increased rates of addiction in populations with brain injury,” he said.

But scientists have not been able to definitively say brain injury can cause addictive behaviour because people who are more likely to have brain injury could simply be the type of people who have less impulse control in the first place.   

This experiment on rats demonstrates a chemical link between brain injury and addiction.

Vonder Haar hopes his findings will lead to new treatment options for head-injury victims as well as addictions patients.

“The next step would be to go in and start to treat those impulse control problems. We will look into whether manipulation of interleukin-12 could improve function or not.”

“Hopefully, if that holds true for brain injury, it may also have relevance in fields like addiction.”

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