TBI increases likelihood of incident sleep disorders in large study of veterans

A traumatic brain injury diagnosis increased the risk for incident sleep disorders over 14 years, according to the results of a longitudinal cohort study of nearly 200,000 veterans published in Neurology.

“One of the most common and immediate consequences of a traumatic brain injury (TBI) are sleep complaints, which significantly impair patients’ quality of life and rehabilitation process,” the researchers wrote. “While it has been hypothesized that TBI might lead to permanent damage to sleep-related brain regions and thus long-lasting sleep disorders, evidence on the longitudinal association between TBI and development of sleep disorders years after the injury is limited. It is also unclear whether different severity of TBI might have different impact on sleep and if the effects of TBI on sleep disorders are more immediate or latent.”

According to the researchers, military veterans with TBI frequently experience comorbid psychiatric conditions, but “little is known” about the link between TI and the risk for incident clinical sleep disorders in this group, particularly PTSD. Yue Leng, PhD, assistant professor of psychiatry at the University of California, San Francisco, and colleagues examined a large national sample of veterans being treated through the Veterans Health Administration health care system to determine the independent link between TBI and long-term risk for incident sleep disorders.

Leng and colleagues included all patients diagnosed with a TBI in the Veterans Health Administration system between October 2001 and September 2015 and age-matched these patients 1:1 to veterans without TBI. The researchers defined the development of a sleep disorder as any inpatient or outpatient diagnosis of sleep apnea, hypersomnia, insomnia or sleep-related movement disorders according to ICD-9 codes after the initial TBI diagnosis or a randomly selected date for those without TBI. They confined the analysis to individuals with at least 1 year of follow-up and omitted veterans with prevalent sleep disorders at baseline.

The study included 98,709 veterans with TBI and 98,709 age-matched veterans without TBI. Mean age of participants was 49 years (±20 years) at baseline and 11.7% were women. Leng and colleagues found that 49.6% of TBI cases were mild; veterans with TBI were less likely to be women and more likely to have comorbidities. The study also demonstrated that patients with TBI were much more likely than those without TBI to have psychiatric conditions, including mood disorders (22.4% vs. 9.3%), anxiety (10.5% vs. 4.4%), PTSD (19.5% vs. 4.4%), substance abuse (11.4% vs. 5.2%) and smoking or tobacco use (13.5% vs. 8.7%). Patients with more severe TBIs were older and less likely to be women and had lower socioeconomic status, a greater number of medical comorbidities and fewer psychiatric conditions.

Over an average follow-up of 5 years (range, 1-14 years), 23.4% of veterans with TBI developed sleep disorders compared with 15.8% of those without TBI, according to study results. After adjusting for age, sex, race, education and income, Leng and colleagues found that patients with TBI were 50% more likely to develop any sleep disorders compared with those without TBI (HR = 1.5; 95% CI, 1.47-1.53). Additional adjustment for medical conditions — including diabetes, hypertension, myocardial infarction and cerebrovascular disease — and psychiatric disorders — including mood disorder, anxiety, PTSD, substance use disorder and tobacco use — resulted in an adjusted HR for developing sleep disorders of 1.41 (95% CI, 1.37-1.44).

Specifically, the researchers found that veterans with TBI were more likely than those without TBI to develop incident sleep apnea (11.4% vs. 8.3%), insomnia (12% vs. 7.2%), hypersomnia (2.1% vs. 1.3%) and sleep-related movement disorders (0.6% vs. 0.4%). Adjustments for demographic, medical and psychiatric conditions resulted in HRs of 1.28 (95% CI, 1.24-1.32) for sleep apnea, 1.5 (95% CI, 1.45-1.55) for insomnia, 1.5 (95% CI, 1.39-1.61) for hypersomnia and 1.33 (95% CI, 1.16-1.52) for sleep-related movement disorders.

The study results demonstrated that the association with sleep disorders was strongest for mild TBIs, did not vary significantly by the presence of PTSD and persisted after a 2-year time lag.

“Increased clinical attention should be paid to both short-term and long-term risk of sleep disorders in [patients with TBI], both the mild and more severe cases. Additional research is needed to determine the underlying mechanisms for a longitudinal link between different severity and types of TBI and development of sleep disorders,” the researchers wrote. “Ultimately, early identification and prevention strategies for sleep disorders after TBI need to be developed and would be critical for improving quality of life and other long-term outcomes in [patients with TBI].”