Secondary endpoints are ( 1 ) tolerability and safety ; ( 2 ) detection of the most sensitive neurocognitive instruments ; ( 3 ) perceptions of Down syndrome adults and caregivers on whether to participate , and assessment experiences ; ( 4 ) distributions of cognitive decline , adaptive behavior , general health/quality of life , service use , caregiver strain , and sample size implications ; ( 5 ) whether A42/A40 is a cognitive decline biomarker .