Overlooking Down Syndrome
Dazee is frustrated because we have not included any discussion of Down Syndrome at this site, even while autism and other forms of severe disability are frequent topics of consideration. There are several reasons for our neglect.
First, the principal contributor to this blog has no experience with these kids. He hasn’t studied them (or animal models of this inherited malady) directly, in any meaningful way. There are better authorities out there in the scientific community.
Second, these children differ from other kids with cognitive impairments that we’ve studied, by the fact that their condition commonly results in the disabling of one of the key brain centers (the “basal nucleus of Meynert”, a main source of the critical neurotransmitter acetylcholine) that is a primary enabler of learning. Our therapeutic approaches are based on the hypothesis that we can progressively improve (to a variable extent, normalize) brain function in even severely impaired kids using their powerful, still-intact capacities for corrective brain change. In Down Syndrome children, this potentially-corrective brain-change machinery is severely dysfunctional.
One very interesting aspect of the neurology of DS is the fact that the basal nucleus is substantially intact in these kids at birth, but its functionality slowly deteriorates — usually over a period of several years — in infancy and very early childhood. These regressive changes have been associated with the child’s genetic fault(s), and may be inescapable. On the other hand, we have long known that the health of this key brain center is directly dependent upon how heavily it is activated, BY LEARNING. If I had a Down Syndrome infant in my family, I would do everything possible to amplify the EARLY learning experiences of that child, then sustain them on a relatively heavy schedule as childhood progresses, believing that by so doing, I might be able to stabilize this key brain center at a significantly higher level of functionality.
It would (scientifically) be relatively easy — but relatively costly — to test this hypothesis, to wit: “A much heavier schedule of early learning will result in the increased activation of the basal nucleus, and thereby, in an upregulation of ‘trophic factors’ that can better sustain its metabolic status and its production of the learning-critical neurotransmitter acetylcholine.” Someone out there should undertake this pragmatic study, because if this hypothesis proved to be true, that outcome would have a major impact on how we approach therapeutics in DS, from baby-hood onward.
Two final thoughts:
1) No structure like the basal nucleus functionally regresses all on its own! It’s ‘failure’ induces — or is paralleled by — complex adaptive brain changes in many other brain centers and regions. There are still important questions about whether the breakdown of the functionality of this key nucleus is a cause — or an effect — of other, parallel changes that distinguish the DS brain from the normal brain. When I say that this nucleus ‘breaks down’, I am really saying that IT fails ALONG WITH a host of related brain centers that normally contribute to, or depend on its actions. I pinpoint ITS failure because it is known to play a central role in enabling learning-driven plasticity.
2) Rett’s Syndrome kids also commonly have a regressive loss of basal nucleus/acetylcholine functionality. Although their problems are more complicated than are those in DS kids, any study evaluating whether or not a more intense, heavier early learning schedule can improve and sustain acetylcholine-based controls would definitely bear relevance for them.