ttained becomes increasingly more delayed as time goes on. Thus although the average delay may be of the order of two months for the very early landmarks (e.g. rolling over, transferring objects), it gradually lengthens and reaches one to two years for function that ordinarily appear at about two years of age. For example an average two year old would be expected to speak in three word sentences, and feed themselves, while a child with Down syndrome might not be able to accomplish this until they were four. Patients with DS also have a higher occurrence of Alzheimer's disease. The exact percentage is currently under debate, with estimates ranging from twenty-five percent to as high as seventy five percent depending on age. This controversy stems from the fact that nearly all Down syndrome patients (upwards of 97%) (Leshin, www.ds-health.com), exhibit a pathology characteristic of Senile dementia. Namely neuronal tangles, and plaque deposits which exhibit themselves approximately fifteen years earlier (some as early as 35 years of age) than in patients without Down's. However recent evidence suggests that there isn't the mental decline in later years as had originally been assumed. Based both on cross-sectional and relatively short-term longitudinal studies, it is claimed that only one-third of persons with DS over 35 years of age show intellectual deterioration. (Leshin, www.ds-health.com) Although the relationship between the numbers of tangle and plaques and degree of dementia in Down syndrome is not known, the most likely theory deal with the threshold level for the number of plaques and tangles necessary to cause dementia. It has been theorized that patients with DS have a higher threshold level for these abnormalities than in non-Down syndrome patients. Sixty to eighty percent of children with DS also have hearing deficits. Brain-stem auditory evoked potentials were examined in 37 adult patients with Down syndrome and in 37 age-...
