Hypnotics use but not insomnia increased the risk of dementia in traumatic brain injury patients

This study was intended to determine whether the use of hypnotics is associated with dementia in traumatic-brain-injury (TBI) patients. Data retrieved from the Longitudinal Health Insurance Database 2000. TBI patients who received a diagnosis of insomnia at 2 or more independent examinations after the index date of TBI were included. The comparison cohort consisted of randomly selected TBI patients who were matched to insomnia cohort patients based on sex and age. The 2 cohorts of TBI patients were subsequently divided into the following 4 study groups: hypnotics users with insomnia (TBI-IH, N=599), insomniacs who did not use hypnotics (TBI-I, N=931), hypnotics users without insomnia (TBI-H, N=199), and people without insomnia who did not use hypnotics (TBI-C, N=4271). Cox proportional-hazards regression models were used to determine the difference in dementia-free survival among the 4 study groups, after adjusting for the propensity score. The adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) of the TBI-IH and TBI-H groups showed that they had a higher risk of dementia (aHRs: 1.86 and 3.98; 95% CIs: 1.15-3.00 and 2.44-6.47, respectively), compared with that of the TBI-C group. However, the risk of dementia in the TBI-I group was not significantly different from that of the TBI-C group (aHR: 1.36; 95% CI: 0.85-2.19). This study suggests that the use of hypnotics is associated with an increased risk of dementia in TBI patients with or without insomnia, whereas insomnia alone is not.