An analysis of brain MRI scans, conducted by University of Maryland School of Medicine (UMSOM) researchers, has uncovered evidence that children who regularly snore have structural changes in particular regions of the brain, which may account for snoring-associated behavioral problems such as lack of focus, hyperactivity, and learning difficulties at school.

The study found that children aged 9–10 years who snored three or more times per week (as reported by their parents) were more likely to have thinner gray matter in several areas in the frontal lobes of their brain, a region that is responsible for higher reasoning skills and impulse control. The results suggested that the thinner cortex in these regions correlated with behavioral disturbances associated with sleep disordered breathing, the severe form of which is known as sleep apnea.

“This is the largest study of its kind detailing the association between snoring and brain abnormalities,” said study lead author Amal Isaiah, MD, PhD, Associate Professor of Otorhinolaryngology – Head and Neck Surgery and Pediatrics at UMSOM. “These brain changes are similar to what you would see in children with attention deficit hyperactivity disorder. Children have loss of cognitive control which is additionally associated with disruptive behavior. Isaiah further advised parents, “If you have a child who is snoring more than twice a week, that child needs to be evaluated. We now have strong structural evidence from brain imaging to reinforce the importance of diagnosing and treating sleep disordered breathing in children.”

The UMSOM team reports on its findings in Nature Communications, in a paper titled, “Associations between frontal lobe structure, parent-reported obstructive sleep disordered breathing and childhood behavior in the ABCD dataset.” The reported research was supported by the National Institute on Drug Abuse (NIDA) and nine other Institutes, Centers, and Offices of the National Institutes of Health.

Obstructive sleep-disordered breathing (oSDB) is a group of conditions commonly associated with snoring. In children the condition is characterized by resistance to breathing during sleep, resulting in snoring, and potentially involving respiratory pauses during sleep, the authors explained. The link between snoring in children and behavioral problems is also well recognized. “Parents frequently report behavioral problems among children who snore,” the authors noted. “The consistent relationship between oSDB and problem behaviors involving deficits in cognitive control, such as inattention and hyperactivity may impact children’s learning and interaction in the classroom…Untreated oSDB is commonly associated with neurobehavioral deficits justifying its diagnosis and management.”

Snoring can cause disrupted sleep throughout the night due to interrupted breathing and reduction in oxygen supply to the brain. And while large, population-based studies have established the link between snoring and behavioral problems such as inattention or hyperactivity, the exact nature of the relationship is not fully understood. A few small studies have reported a correlation between sleep apnea—when pauses in breathing are prolonged—and certain brain changes, but little is known about whether these changes contribute to the behavioral issues seen in some children with oSDB. “Evidence of brain structural changes in children with oSDB have been limited to a few small studies of associations between obstructive sleep apnea and alterations in brain tissue or neuronal integrity,” the team commented.

oSDB can be treated by carrying out tonsillectomy and adenoidectomy, which are considered the first line of treatment of children with symptoms of snoring, breathing pauses during sleep, and mouth breathing. However, a significant percentage of children are misdiagnosed as having ADHD and treated with stimulant medications. To address the existing knowledge gap and examine the relationships between snoring, brain structure, and behavioral problems, Isaiah and colleagues examined MRI brain images from more than 10,000 children, aged 9–10 years, who were enrolled in the Adolescent Brain Cognitive Development (ABCD) Study, a long-term study of child health and brain development in the US.

Confirming the results of previous work, their statistical analyses revealed a positive correlation between habitual snoring and behavioral problems, such that the children who most frequently snored generally exhibited worse behavior, according to an assessment completed by parents.

The findings further showed that snoring is linked to smaller volumes of multiple regions of the brain’s frontal lobe, an area involved in cognitive functions such as problem solving, impulse control, and social interactions. The statistical analysis suggested that the brain differences seen in children who snore may contribute to the behavioral problems, although additional work on how snoring, brain structure, and behavioral problems change over time is needed to confirm a causal link. “Together, these results provide evidence for brain-structure-related determinants of the relationship between parent-reported symptom burden of oSDB and problem behaviors,” they wrote. “While causal effects cannot be inferred due to the cross-sectional nature of the current study, these results are consistent with a proposed mediational model that links oSDB with executive dysfunction via injury to the prefrontal cortex…These results also provide population-based evidence for a biologically plausible model linking the burden of oSDB with neurobehavioral problems via brain characteristics shaped by hypoxia with or without sleep disruption.”

The findings thus point to oSDB as a potential reversible cause of behavioral problems, suggesting that children might be routinely be screened for snoring. Those who are found to snore habitually might then be referred for follow-up care. Such care may include assessment and treatment for conditions that contribute to oSDB, such as obesity, or evaluation for surgical removal of the adenoids and tonsils.

“We know the brain has the ability to repair itself, especially in children, so timely recognition and treatment of obstructive sleep disordered breathing may attenuate these brain changes,” said study co-author Linda Chang, MD, MS, Professor of Diagnostic Radiology and Nuclear Medicine who is a co-principal investigator on the ABCD study. “More research is needed to validate such mechanisms for these relationships which may also lead to further treatment approaches,”

The researchers plan to conduct a follow-up study to determine whether children who continued to snore experienced worsening brain findings on their MRI.

“For the first time, we see evidence on brain imaging that measures the toll this common condition can take on a child’s neurological development,” commented E. Albert Reece, MD, PhD, MBA, executive vice president for Medical Affairs, UM Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean, University of Maryland School of Medicine. “This is an important finding that highlights the need to properly diagnose snoring abnormalities in children.”

The ABCD Study, the largest of its kind in the United States, is tracking nearly 12,000 youth as they grow into young adults. Investigators regularly measure participants’ brain structure and activity using magnetic resonance imaging (MRI) machines, and collect psychological, environmental, and cognitive information, as well as biological samples. The goal of the study is to define standards for normal brain and cognitive development and to identify factors that can enhance or disrupt a young person’s life trajectory.