Alzheimer dementia in Down's syndrome: the relevance of cognitive ability.

More years of education have been found to be associated with a lower rate of Alzheimer disease (AD) in individuals without intellectual disability. It has been proposed that education reflects greater 'synaptic reserve' and that greater synaptic reserve may defer the development of AD. The present study compared individuals with Down's syndrome (DS) who were found to have symptoms of dementia with those who remained symptom-free to determine if the two groups differed in their level of education, employment, recreational activities, years in an institution or overall level of cognitive functioning. Thirty-five adults with DS aged between 29 and 67 years were assessed. The participants were recruited from a community health facility and included individuals with a wide range of ability levels. Neuropsychological testing, caregiver report and the Dementia Scale for Down Syndrome (Gedye 1995) were used to identify decline in participants over periods of 6 months to 3 years. After the effect of age was statistically removed, multiple regression analyses revealed that level of cognitive functioning was significantly associated with decline such that a higher level of cognitive functioning predicted less decline. None of the environmental variables (i.e. educational level, years in an institution and employment) were directly associated with decline; however, a post hoc regression using level of cognitive functioning as the outcome variable revealed that level of cognitive functioning itself was associated with these environmental variables. A higher level of cognitive functioning was associated with fewer cases of dementia in individuals with DS, and level of cognitive functioning appears to be associated with environmental factors such as level of education, years in an institution and employment. The present findings suggest that environmental interventions aimed at improving level of cognitive functioning may also be useful in deferring the onset of dementia.

Ultrasound velocity and attenuation at different skeletal sites compared with bone mineral density measured using dual energy X-ray absorptiometry.

Measurements of ultrasound velocity were performed in the tibia in a group of 89 female subjects (mean age 50.6 years). Velocity and broadband ultrasound attenuation (BUA) measurements were performed in the os-calcis in a group of 100 male and female subjects (mean age 55.8 years). Dual energy X-ray absorptiometry (DEXA) scans were also performed on all of these subjects enabling measurements of lumbar spine and femoral neck bone mineral density (BMD) to be obtained. In two small subgroups of the above groups, each comprising 20 subjects, measurements of tibial BMD and os-calcis BMD were also performed. Tibial BMD and ultrasound velocity were found to be well correlated (r = 0.71), although both spine and femoral neck BMD were poorly correlated with ultrasound velocity in the tibia (r = 0.299 and 0.072, respectively). BUA of the os-calcis was moderately correlated with BMD at the same site (r = 0.44) and showed similar or slightly better correlations with BMD measurements of the lumbar spine and femoral neck (r = 0.410 and 0.537, respectively). Ultrasound velocity in the os-calcis was well correlated with os-calcis BMD (r = 0.729) but only moderately correlated with spine and femoral neck BMD (r = 0.470 and 0.498, respectively). This study suggests that BUA and ultrasound velocity measurements of the os-calcis are better predictors of BMD at the critical skeletal sites of the lumbar spine and femoral neck than ultrasound velocity in the tibia. Ultrasound velocity in the tibia and the os-calcis was found to be a good predictor of the BMD in the measured bone.