Hypertension and Advanced Age Increase the Risk of Cognitive Impairment after Mild Traumatic Brain Injury: A Registry-Based Study

Background As the global population ages, the incidence of traumatic brain injury (TBI) is increasing. Whereas mild TBI can impair the cognitive function of older adults, the cause and background of mild TBI-induced cognitive impairment remain unclear, and the evaluation of risk factors for cognitive impairment after mild TBI remains open for consideration, especially in the aging population. This study aimed to evaluate the risks associated with cognitive impairment following mild TBI. Methods Between January 2006 and December 2018, a total of 2209 patients with TBI required hospitalization in Shimane Prefectural Central Hospital. Mild TBI was defined as a Japan Coma Scale ≤10 at admission. Patients' cognitive function was measured with the Hasegawa Dementia Rating Scale-Revised or Mini-Mental State Examination at least twice during the patients' hospital stays. The odds ratio (OR) and 95% confidence interval (CI) of each considered risk factor was calculated with multivariable logistic regression analysis after univariate analysis. Results Among 1674 patients with mild TBI, 172 patients underwent cognitive function examinations, of whom 145 (84.3%) were found to have cognitive impairment at discharge. Significant risk factors for cognitive impairment included age (P = 0.008) and hypertension (P = 0.013) in univariate analysis; and age (OR, 1.04: 95% CI, 1.01–1.07) and hypertension (OR, 5.81: 95% CI, 1.22–27.68) by multivariable analysis. Conclusions Older patients with hypertension displayed a significantly higher risk for cognitive impairment after even mild TBI. These patients warrant careful management after even mild TBI.