Research Study on Link between Dementia and Down syndrome
Among the many phenotypic characteristics of DS, that of precocious aging and its correlates has gained much recent attention. The estimated lifespan of DS individuals was once less than 20 years, however, advances in medical technology have lengthened the average lifespan considerably.
Fifty percent of the DS population is expected now to live to at least age 35 (Thase, 1982). When compared with non-DS institutionalized mentally retarded individuals, mortality rates for DS persons does not vary significantly until age 40 after which the mortality rate in DS individuals accelerates rapidly. Due to bias caused by institutional retention and release policies, these rates could be artificially inflated. Irrespective of institutionalization, similar divergent mortality rates have been found between DS and non-DS mentally handicapped individuals. From age 30 to age 40, the survival rates of DS and other moderately to severely mentally retarded populations become rapidly disparate and maintain a 15-20 difference throughout the remaining years of life the DS population having poorer survivorship.
Precocious aging in DS individuals is particularly significant for educators and primary caregivers. The aging process tends to occur about 10 years earlier than with the general population. Physical symptoms include skin dryness and coarsening, and gum recession accompanied by loss of teeth. Unfortunately, aging affects more complex physiological processes as well. These bear directly on the cognitive, social and physical well-being of DS persons. There ward for extended survival for many DS persons is prehensile dementia or dementia of the Alzheimer type (DAT). In addition, behavioral degeneration in older DS individual’s proceeds similarly to that of individuals with DAT.
Clinical documentation of Alzheimer like dementia in DS patients is limited by the retrospective nature of many studies and the use of institutionalized profoundly retarded populations in others. Diagnosis of dementia is particularly difficult in retarded persons who are already functioning at low levels of cognitive, social, and occupational scales, diagnoses, therefore, must depend on other information from family members or caretakers.
Short-term memory (STM) loss is frequently the first functional sign of progressive neurological and behavioral degeneration in both DS and non-DS Alzheimer-affected populations. Neither age-matched, non-DS mentally retarded controls. DS individuals above age 35 have demonstrated a higher incidence of recent memory loss; shortterm visual retention deficits; difficulty in object identification (aphasia, agnosia); loss of vocabulary; loss of usual affectionate response to others; irritability; emotional disturbances; slowness; and loss of interest in their surroundings.