In fact, about half of the children in the study who were found to have Attention-Deficit/Hyperactivity Disorder before tonsil surgery no longer met criteria for this diagnosis one year later. Other cognitive and behavioral issues also improved.

On the whole, the 78 children who had their tonsils out were much more likely than a comparison group of 27 children to have had behavior and sleep problems at the start of the study. But by the end of the study, tests showed little difference between the two groups.

The research paper is published online in the April issue of the journal Pediatrics by a team from the University of Michigan Health System. Data were collected from rigorous tests of sleep and breathing at night, and attention and behavior during the day. The results support previous observations of a link between children’s sleep-related breathing problems — such as snoring and breathing interruptions called apneas — and daytime behavior problems.

The researchers caution that their results do not yet prove cause and effect, and that tonsillectomy is not usually a “cure” for ADHD. But, they say, the growing body of evidence on this issue suggests that a significant number of children with inattention, hyperactivity, or sleepiness during the day – and also sleep-breathing problems at night – may benefit during both the night and day by tonsillectomy, an operation that was once performed on more than a million children a year but has become much less common in recent decades.

The procedure, also called adenotonsillectomy when both the tonsils and structures called adenoids are removed, is now performed on a few hundred thousand children a year. Nearly half of them have the surgery because enlarged tonsils and adenoids block the flow of air through their throat and impair their ability to breathe, and most of the rest because of repeated ear and throat infections. Almost all of the children who had surgery in the new study were thought by their surgeons to have symptoms of sleep apnea.

“These findings help support the idea that sleep-disordered breathing is actually helping to cause behavioral problems in children, and making them sleepy,” says lead author Ronald Chervin, M.D., M.S., director of the U-M Sleep Disorders Center and co-leader of the U-M Center for Sleep Science. “This is one of the first studies to document, using gold-standard measures, that all of these sleep and behavior problems tend to resolve one year after enlarged tonsils and adenoids are removed.”

One of the most striking findings – that children once diagnosed with ADHD no longer had the condition a year after tonsillectomy – occurred in 11 of 22 children with ADHD. This means that sleep and breathing problems are only part of the ADHD puzzle, and that tonsillectomy isn’t a cure-all for ADHD, notes Chervin, an associate professor of neurology at the U-M Medical School.

A few children even developed new ADHD a year after surgery. Chervin says this supports previous evidence that damage from sleep-disordered breathing may occur in early years, even though the result is not seen until later. If confirmed, this would mean that early diagnosis and treatment of sleep-disordered breathing are particularly important.

When they entered the study, and before any surgery, all the children in the study had their behavior assessed by a child psychiatrist, as well as by their parents, who completed standardized questionnaires. The children had their attention span and short-term memory measured using a standard computer-based test, and spent a night in the U-M Michael S. Aldrich Sleep Disorders Laboratory. There, they were monitored for breathing problems during sleep, and also for their level of sleepiness, as measured by how long it took them to fall asleep in a series of naps.

All the tests were repeated a year after the children had a tonsillectomy at U-M C.S. Mott Children’s Hospital or St. Joseph Mercy Health System, performed by otolaryngologists (ear, nose and throat doctors) from any of eight practices in the local area. For the comparison group, who had non-tonsil surgery or no surgery, the second round of testing was performed a year after initial tests. The researchers analyzed the test results using sophisticated statistical analysis.

Among those children scheduled for tonsillectomy, the sleep-breathing tests showed that before surgery, half of them had obstructive sleep apnea (OSA), usually in the mild to moderate range, in contrast to only one of the comparison children. At the end of the study, only 12 percent of the tonsillectomy patients had OSA, including one patient who hadn’t had it before tonsillectomy, compared with 3 children among the comparison patients who completed the sleep test series. In all, five children did not complete follow-up tests.

In people of any age, OSA occurs when breathing stops and starts repeatedly during the night, often in part because the throat is narrowed or blocked, keeping sufficient air from getting into the windpipe and lungs. People with sleep apnea often snore, or snort and gasp throughout the night, though not all snorers have sleep apnea. About one to three percent of children have OSA, including a good number of those children who snore regularly. Enlarged tonsils are a common cause of the sleep disorder in children, while obesity, allergies, acid reflux and structural abnormalities in the head and neck also contribute to it in children and adults.

Interruptions in breathing during sleep can cause the brain to “wake up” to some extent, even if the sleeping person is not aware of it. These repeated interruptions disturb the sleep patterns that are essential to a good night’s sleep – and are thought to be the reason why daytime behavior might be affected by poor breathing during the night. Sleep apnea is also linked to heart and blood pressure problems, and in children, to slow growth.

The researchers also compared the tonsillectomy patients who had had OSA before surgery with those who had not. In all, the children who had not had it before tonsillectomy were just as likely as the children with OSA to have a high score on standard tests of hyperactivity, and just as likely to have behavioral improvement after tonsillectomy.

As a result of this finding and other data, the study adds to an issue that’s currently puzzling sleep researchers: Why the results of sleep tests to monitor brain activity and breathing don’t always correlate with children’s daytime behavior. The standard measures used to assess children’s sleep problems, and the threshold levels that are used to assess the severity of a sleep problem, may need to be reevaluated, says Chervin.

To explore this issue further, he and his U-M colleagues are now recruiting patients for a study that will compare those standard measures with new ones, including a measure of how hard children work to breathe during the night, and another that looks for subtle changes in brain activity with every labored breathing cycle.

The bottom line for parents, Chervin and his colleagues say, is that any child who snores regularly, or has other signs of breathing problems during sleep, may benefit from an evaluation for sleep problems and perhaps from tonsillectomy – especially if the child is also having behavior problems at home or school.

“If you have a child who has difficulties with attention deficit, hyperactivity, or daytime sleepiness, there may be something that can be done about it if the child proves to have a sleep disorder,” Chervin says. “An undiagnosed sleep disorder is not the solution for all children with ADHD. But it could be something worth looking into for a substantial minority, especially those children with symptoms that suggest a sleep disorder such as sleep apnea.”

In addition to Chervin, the study’s authors are Deborah Ruzicka, R.N., Ph.D., of the Sleep Disorders Center; Bruno Giordani, Ph.D., Elise Hodges, Ph.D., and James Dillon, M.D., of the U-M Department of Psychiatry; Robert Weatherly, M.D., formerly of the U-M Department of Otolaryngology and now at the University of Kansas; Carole Marcus, MBBCh, of the Sleep Center at the Children’s Hospital of Philadelphia; and Kenneth Guire, M.S., of the U-M School of Public Health.

Women smokers who become pregnant have long been encouraged to reduce or eliminate their nicotine intake. A new study being published in the June 15th issue of Biological Psychiatry provides further reason to do so, as it presents new evidence that in utero exposure to smoking is associated with attention deficit/hyperactivity disorder (ADHD) problems in genetically susceptible children.

The study investigated male and female twin pairs, aged 7 – 19 years, to assess the relationship between genetic variations, prenatal substance exposures, and ADHD sub-types. Rosalind Neuman, Ph.D., one of the study’s authors, explains the findings: “When genetic factors are combined with prenatal cigarette smoke exposure, the ADHD risk rises very significantly. When the child has either or both of two specific forms of dopamine pathway genes (DAT and DRD4), and was exposed to cigarette smoking in utero, the risk for having combined type ADHD (many inattention and hyperactive/impulsive symptoms) increased 3 to 9 fold.”

John H. Krystal, M.D., Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, adds, “These data highlight a new risk of maternal smoking, increasing the risk for ADHD in their children. ADHD, in turn, increases the risk for substance abuse. Thus, it appears that in utero exposure to nicotine may help to perpetuate a cycle across generations that links addiction and behavioral problems.”

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