BACKGROUND:Traumatic brain injury (TBI) exerts a significant impact on society with regards to physical, affective, and cognitive impairment. The consequent cognitive sequelae include a problem in memory, attention, concentration, and processing speed. Following traumatic brain injury, inflammatory response developed, characterised by increased interleukin 1-β (IL-1β) levels in the blood. IL 1-β at pathophysiological concentration has been reported to cause an inhibition of the expression of long-term potentiation (LTP) in the areas CA1, CA3, and dentate gyrus of the hippocampus.AIM:This study aims to determine whether high IL-1β serum is a predictor of decreased cognitive function in mild TBI.METHODS:This is a prospective cohort study conducted at the emergency room, surgical and neurologic ward at Sanglah Hospital from November 2017 until January 2018. As many as thirty-five mild TBI with normal IL-1β serum (< 0.0565 pg/ml) and thirty-five of those with high IL-1β serum (≥ 0.0565 pg/ml) subjects were included within the corresponding period. The decrease of cognition after trauma was measured seven days later.RESULTS:This study demonstrated that group with high IL-1β serum levels were at higher risk of suffering from cognitive impairment after TBI when compared with the group with normal IL-1β serum levels (RR = 2.6; 95% CI 1.49-4.55, p < 0.001).CONCLUSION:Mild TBI with high serum IL-1β levels were more than twice likely to experience decreased cognitive function than those with normal IL-1β levels.