A new study in the journal Pediatrics suggests this common procedure may improve the condition of kids diagnosed with attention defecit/hyperactivity disorder (ADHD). I think it’s an excellent case of some true “alternative explanations” for the data.
Creationists often try to validate their position by saying that both they and mainstream scientists start from the same data, but that creationists use their “Bible glasses” to interpret it, while scientists view it through their “evolution glasses.” In other words, they’re not wrong–it’s just a different interpretation of the same data, and where you end up depends on your initial biases and worldview. Though this is bogus when it comes to creationism, there are indeed real debates in the literature, where two hypotheses may be similarly compelling.
Such is the example of the new Pediatrics paper. The study referenced is a sleep study–specifically, looking at children with obstructive sleep apnea (OSA), a disorder where the sufferers stop breathing in their sleep. This can happen hundreds of times a night, for up to a minute at a time in adults. In children, the disorder seems to be more mild, but can lead to behavior problems and cognitive impairment. One treatment for this disorder is adenotonsillectomy (AT)–removal of the adenoids and tonsils. This typically improves breathing and resolves the condition.
The authors of the new study decided to examine whether this procedure also affected behavior. They enrolled 78 kids between the ages of 5 and 13 who were scheduled for an adenotonsillectomy, along with 27 controls undergoing a variety of other surgical procedures (but not AT). Each subject was assessed at enrollment to determine behavior (including the diagnosis of ADHD), cognition, and the presence of sleep disorders. Initially, just over half of the AT group was found to have sleep apnea (OSA), compared to 4% of the controls (just one patient). At the one-year follow-up, OSA was reduced to 12% of the tonsillectomy group, and again, one patient in the control group. Similarly, 28% of the tonsillectomy subjects initially were diagnosed with ADHD, compared to 7% of the controls (2 subjects). At one-year follow-up, half of the ADHD-diagnosed kids in the tonsillectomy group no longer qualified for diagnosis, and the percent of ADHD-diagnosed subjects was not significantly different between the tonsillectomy group and the control group at the one year follow-up. Most interestingly, they note that both at baseline and follow-up, the frequency of ADHD diagnosis was identical among tonsillectomy subjects with and without sleep apnea. Minimal improvement in attention was associated with diminished sleep apnea.
So, what did they conclude from their data?
Severe improvement in our subjects after AT provides new suggestive evidence for a cause-and-effect relationship between sleep-disordered breathing (SDB)… and several adverse behavioral, cognitive, and mental health outcomes. However, our non-randomized study cannot prove cause and effect. Moreover, the poor correspondence between SDB measures and neurobehavioral outcomes…seems to run directly counter to expectations if SDB causes these morbidities.
What they totally neglected to even mention was an alternative reason that the kids improved when they had their tonsils removed. I’ve mentioned previously something called PANDAS: Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal infections. PANDAS includes not only ADHD, but also other afflictions such as Tourette’s syndrome and obsessive-compulsive disorder (OCD). All three target the same area of the brain: the basal ganglia. This is the same portion afflicted in another disease triggered by streptococcal infection: Sydenham’s chorea, a manifestation of rheumatic fever. One study of Sydenham’s chorea patients, moreover, showed that approximately 70% of those questioned reported an episode of OCD-like behavior. Additionally, other studies have found significantly increased rates of rheumatic fever among the parents or grandparents of children who have been diagnosed with either Sydenham’s chorea or PANDAS. Thus, children in the PANDAS group may have inherited a susceptibility to post-streptococcal sequelae similar to that reported for children with Sydenham’s chorea. All of these lines of evidence point to a role for Strep pyogenes in the development of ADHD, OCD, and Tourette’s syndrome.
How then does the tonsillectomy play into this? Streptococcal infections can, of course, be treated with antibiotics–Streptococcus pyogenes even remains highly susceptible to that old workhorse, penicillin. But these bacteria can play hide and seek: they can survive for quite some time within our own cells, which antibiotics can’t penetrate, and where the bacteria remain protected from attack by our immune system. And the cells they typically hide in are located in the tonsils–so remove the tonsils, remove the reservoir of strep, disorder resolves–just as the authors of the Pediatrics study saw. Easy-peasy, right?
Of course, even in the population of children who’d had their tonsils removed, there were still kids who had ADHD a year later. Again, this is one thing that makes these types of conditions difficult to study, as I mentioned here. Strep may be one cause; sleep may be a contributing factor; and there may be other causes as well, separate from strep. This is an ongoing area of research, where many questions remain and as such, alternate interpretations of the data are justified. Keep an eye on this and watch how it’s resolved: via attempts at legislation and political wrangling to teach our MDs one side or another, or by spirited debate and scientific disagreements in the literature, and the accumulation of additional evidence to either support or refute one of the views. I’ll bet a bottle of single-malt scotch it’ll be the latter.
Chervin RD, et al. 2006. Sleep-Disordered Breathing, Behavior, and Cognition in Children Before and After Adenotonsillectomy. PEDIATRICS Vol. 117 No. 4 pp. e769-e778.
Image from http://www.adhd-schools.com/images/troubled.jpg