WEDNESDAY, May 25, 2022 (HealthDay News) -- Variability of age at symptom onset for Alzheimer disease with Down syndrome is similar to autosomal-dominant Alzheimer disease, while mortality data are compatible with fully penetrant Alzheimer disease, according to a study published online May 23 in JAMA Network Open.
Maria Florencia Iulita, Ph.D., from Universitat Autònoma de Barcelona in Spain, and colleagues assessed whether the variability in symptom onset of Alzheimer disease in Down syndrome is similar to autosomal-dominant Alzheimer disease, as well as its association with mortality. In addition to a literature search and meta-analysis, the analysis included mortality data from U.S. death certificates (77,347 case records from 1968 to 2019) and 889 individuals from the Down Alzheimer Barcelona Neuroimaging Initiative.
The researchers found that the estimate of age at onset was 53.8 years and the estimate of age at death was 58.4 years for Alzheimer disease dementia in Down syndrome. Ages at onset were comparable to those reported in autosomal-dominant Alzheimer disease. There was an increase noted in life expectancy in Down syndrome (median, 1 year in 1968 to 57 years in 2019) using U.S. mortality data, but with clear ceiling effects in the highest percentiles of age at death in the last decades. These mortality data corresponded to limits projected with a fully penetrant Alzheimer disease in up to 80 percent of deaths (corresponding to the highest percentiles). In 2019, racial disparities persisted and were more pronounced in the lower percentiles (10th percentile: Black individuals, 1 year; White individuals, 30 years) than in the higher percentiles (90th percentile: Black individuals, 64 years; White individuals, 66 years).
"Lifespan in persons with Down syndrome will not increase until disease-modifying treatments for Alzheimer disease are available," the authors write.
Several authors disclosed financial ties to the pharmaceutical industry.