A new study by Renato Cocchi, M.D., PhD., suggests that tongue protrusion in children with Down syndrome is “an aspecific symptom, without any relationship with the chromosome 21. Probably it is a symptom of internal metabolic stress with irritability of the hypoglossal nerve nucleus. This fact elicits a stimulation excess of the genioglossus and ioglossus muscles, leading to repetition of the tongue protrusion movement, without any apparent purpose.”
Cocchi based his conclusions on research using antistress drug therapy on children with Down syndrome with an average age at first consultation of 36 months, for treatment over fourteen months, and found similar results in both boys and girls. The information was posted on the Internet in December 2006 and reprinted at the Riverbend Down Syndrome Parent Support Group, which you can read here.