Impulsivity problems may be linked to levels of an inflammatory molecule in the brain. This discovery comes from new research by scientists at the University of British Columbia. The scientists gave rats with brain injuries a reward test to measure implusive behavior. Rats that were unable to wait for the delivery of a large reward, and instead preferred an immediate, but small reward, were considered more impulsive. The researchers found no difference in impulsive behavior, regardless of the severity of the brain injury The impulsive behavior persisted eight weeks after injury, even after memory and motor function returned. Samples of frontal cortex brain tissue revealed a substantial increase in levels of an inflammatory molecule, known as interleukin-12, that correlated with levels of impulsive behavior. The findings are important because impulsivity is linked to a vulnerability to addiction.