March 09, 2021
Veterans with who have suffered a traumatic brain injury (TBI) are significantly more likely to develop insomnia and other sleep problems years later compared to their counterparts who have not suffered a brain injury, a new study shows.
Results of a large longitudinal study show that those with TBI were about 40% more likely to develop insomnia, sleep apnea, excessive daytime sleepiness, or another sleep disorder in later years, after adjusting for demographics and medical and psychiatric conditions.
Interestingly, the association with sleep disorders was strongest among those with mild TBI vs a more severe brain injury.
The study showed that the risk for sleep disorders increased up to 14 years after a brain injury, an indicator that "clinicians should really pay attention to sleep disorders in TBI patients both in the short term and the long term," study investigator Yue Leng, MD, PhD, assistant professor, Department of Psychiatry and Behavioral Sciences, University of California, San Francisco, told Medscape Medical News.
The study was published online March 3 in Neurology.
First Long-Term Look
TBI is common among veterans, who may have sleep complaints or psychiatric symptoms, but previous studies into the consequences of TBI have examined the short- vs long-term impact, said Leng.
To examine the longitudinal association between TBI and sleep disorders, the investigators examined data on 98,709 Veterans Health Administration patients diagnosed with TBI and an age-matched group of the same number of veterans who had not received such a diagnosis. The mean age of the participants was 49 years at baseline, and 11.7% were women. Of the TBI cases, 49.6% were mild.
Researchers used an exposure survey and diagnostic codes to establish TBI and its severity.
Patients with TBI were more likely to be male and were much more likely to have a psychiatric condition, such as a mood disorder (22.4% vs 9.3%), anxiety (10.5% vs 4.4%), posttraumatic stress disorder (PTSD) (19.5% vs 4.4%), or substance abuse (11.4% vs 5.2%). They were also more likely to smoke or use tobacco (13.5% vs 8.7%).
During a follow-up period that averaged 5 years but ranged up to 14 years, 23.4% of veterans with TBI and 15.8% of those without TBI developed a sleep disorder.
After adjusting for age, sex, race, education, and income, those who had suffered a TBI were 50% more likely to develop any sleep disorder compared to those who had not had a TBI (hazard ratio [HR], 1.50; 95% CI; 1.47 – 1.53.)
After controlling for medical conditions that included diabetes, hypertension, myocardial infarction, and cerebrovascular disease, as well as psychiatric disorders such as mood disorders, anxiety, PTSD, substance use disorder, and tobacco use, the HR for developing a sleep disorder was 1.41 (95% CI, 1.37 – 1.44).
The association with TBI was stronger for some sleep disorders. Adjusted HRs were 1.50 (95% CI, 1.45 – 1.55) for insomnia, 1.50 (95% CI, 1.39 – 1.61) for hypersomnia, 1.33 (95% CI, 1.16 – 1.52) for sleep-related movement disorders, and 1.28 (95% CI, 1.24 – 1.32) for sleep apnea.
It's unclear what causes postinjury sleep problems, but it could be that TBI induces structural brain damage, or it could affect melatonin secretion or wake-promoting neurons.
Damage to arousal-promoting neurons could help explain the reason the link between TBI and sleep disorders was strongest for insomnia and hypersomnia, although the exact mechanism is unclear, said Leng.
Greater Risk With Mild TBI
Overall, the association was stronger for mild TBI than for moderate to severe TBI. This, said Leng, might be due to differences in the brain injury mechanism.
Mild TBI often involves repetitive concussive or subconcussive injuries, such as sports injuries or blast injury among active-duty military personnel. This type of injury is more likely to cause diffuse axonal injury and inflammation, whereas moderate or severe TBI is often due to a direct blow with more focal but severe damage, explained Leng.
She noted that veterans with mild TBI were more likely to have a psychiatric condition, but because the study controlled for such conditions, this doesn't fully explain the stronger association between mild TBI and sleep disorders.
Further studies are needed to sort out the exact mechanisms, she said.
The association between TBI and risk for sleep disorders was reduced somewhat but was still moderate in an analysis that excluded patients who developed a sleep disorder within 2 years of a brain injury.
This analysis, said Leng, helped ensure that the sleep disorder developed after the brain injury.
The researchers could not examine the trajectory of sleep problems, so it's not clear whether sleep problems worsen or get better over time, said Leng.
Because PTSD also leads to sleep problems, the researchers thought that having both PTSD and TBI might increase the risk for sleep problems. "But actually we found the association was pretty similar in those with, and without, PTSD, so that was kind of contrary to our hypothesis," she said.
The new results underline the need for more screening for sleep disorders among patients with TBI, both in the short term and the long term, said Leng. "Clinicians should ask TBI patients about their sleep and they should follow that up," she said.
She added that long-term sleep disorders can affect a patient's health and can lead to psychiatric problems and neurodegenerative diseases.
Depending on the type of sleep disorder, there are a number of possible treatments. For example, for patients with sleep apnea, continuous positive airway pressure treatment may be considered.
Commenting for Medscape Medical News, Frank Conidi, MD, director, Florida Center for Headache and Sports Neurology, CEO, Brainsport, Team Neurologist, the Florida Panthers of the National Hockey League, and past president, Florida Society of Neurology, said the study is "by far" the largest to investigate the correlation between sleep disorders and head trauma.
The design and outcome measures "were well thought out," and the researchers "did an outstanding job in sorting through and analyzing the data," said Conidi.
He added that he was particularly impressed with how the researchers addressed PTSD, which is highly prevalent among veterans with head trauma and is known to affect sleep.
The new results "solidify what those of us who see individuals with TBI have observed over the years, that there is a higher incidence of all types of sleep disorders" in individuals with a TBI, said Conidi.
However, he questioned the use in the study of guidelines to classify the various types of head trauma. These guidelines, he said, "are based on loss of consciousness, which we have started to move away from when classifying TBI."
In addition, Conidi said he "would have loved to have seen" some correlation with neuroimaging studies, such as those used to assess subdural hematoma, epidural hematoma, subarachnoid hemorrhage, and diffuse axonal injury, but that this "could be an impetus for future studies."
In "a perfect world," all patients with a TBI would undergo a polysomnography study in a sleep laboratory, but insurance companies now rarely cover such studies and have attempted to have clinicians shift to home sleep studies, said Conidi. "These are marginal at best for screening for sleep disorders," he noted.
At his centers, every TBI patient is screened for sleep disorders and, whenever possible, undergoes formal evaluation in the sleep lab, he added.
The study was supported by the US Army Medical Research and Material Command and the US Department of Veterans Affairs.Leng and Conidi have disclosed no relevant financial relationships.