How old is the Down's patient? There is a local program here in the U.S. that initiates therapy (from PT, OT, and Speech) at 6 months old called "Early Intervention" which is headed by the federal program Center For The Developmentally Disabled (CFDD). They say that it is vital that Down's children begin therapy as early as possible. The earlier the intervention the more successful the outcome. PT is crucial because as the previous post said, Down's children have low muscle tone and need help with strengthening, balance, etc. early on. Check with your CFDD for more info.
Hope this helps, let me know what you find out.
DF