In the 1950s to 1970s, it used to be a rite of passage for young children to get their tonsils taken out. These days, we're a lot more conservative with tonsillectomy, and frequently, parents are told that their child will grow out of their tonsils. While this is true in some cases, there's a consequence to the watching and waiting option.
Your tonsils are lymphoid tissue that's part of Waldeyer's ring, which is a ring of lymphoid tissue made of the palatine tonsils (your typical tonsils), the adenoids (in the back of the nose), and the lingual tonsils (at the base of the tongue in the midline). In some children with overdeveloped lymphoid tissues, you'll see a communication between all four of these glands, forming a complete circle. These tissues are normally involved in educating your immune system, since everything you breathe or swallow has to go through this ring. As a result, it's expected that the tonsils (and adenoids) will be enlarged during the ages of 3-5.
However, with the shrinking size of modern human jaws, now there's less room for the normal-sized tonsils, which takes up relatively more space. This aggravates more frequent obstructions and arousals, leading to more inflammation from refluxed stomach contents and more swelling of the tonsils. The chronic negative pressure created from this process can prevent proper jaw enlargement, similar to what can occur with bottle-feeding. In many children, their snoring and sleep problems will prompt the parents to see an ENT for tonsillectomy. For children with mild to moderately enlarged tonsils that are not causing any symptoms, or those that are symptomatic but are told that they'll outgrow it, there can be permanent long-term consequences.
In children with huge tonsils, one of the reasons why they look so big is that the space that the tonsils sit in is too narrow. Taking out the tonsils can make a dramatic difference is most children, but there are some children that won't respond to tonsillectomy or only partially. One recent meta-analysis showed that adenotonsillectomy was helpful in about 2/3 of all children. But the remaining 1/3 still had residual symptoms or signs of obstructive sleep apnea. These are the children that have smaller jaws than the children who responded to the procedure.
In a recent Stanford University study, children who were scheduled for tonsillectomy were divided into two groups. One group underwent standard tonsillectomy, and the other under went rapid maxillary palatal expansion. The results were equivalent for both groups. When children in both groups were crossed over and given the other procedure, the overall results were additive. This just goes to show that one reason why you can have large tonsils that that your jaw is too small. Of course, everyone is on a continuum, and as usual in modern medicine, you're treated only if you are at the extreme end of the continuum.
This is pure speculation, but I wonder if the significant increase in the rate of ADHD in the 1980s and 1990s could be related to the dramatic decline in the rate of tonsillectomies. Furthermore, since the peak incidence of autism is around ages 3-4, it's interesting that this is also the time that the tonsils become enlarged in most children. If you have enlarged tonsils to begin with, any simple cold or infection (even vaccines!) can cause swelling which starts a vicious cycle, leading to a sudden increase in breathing problems and poor sleep. Sleep apnea by definition causes systemic inflammation and an increased susceptibility to form microscopic clots in the brain.
This is also the time (around age 4) when the voice box reaches its' final position below then tongue as it descends from its' original position behind the tongue. A space is created behind the tongue and between the soft palate and the epiglottis called the oropharynx, which exist only in humans, and allows for complex speech.
One last interesting phenomenon to point out is that in the early 1990s, parents were recommended to place infants on their backs, to prevent SIDs. We know that back sleeping lowers your time spent in deep sleep and leads to more frequent arousals.
All these factors taken together may be what's developed into the "perfect storm," leading to the dramatic rise in ADHD and autism in our current times. Obviously, there are many other dominant theories for ADHD and autism, but from a sleep-breathing standpoint, what I propose is something that definitely needs to be proven in clinical studies.
What do you think about all this? Please enter your responses in the comments box below.