We agree with Margallo-Lana and colleagues that the measurement of cognitive decline in DS is difficult, and for that reason our study used a validated dementia scale. Our control group was closely matched to the treated group in regard to age, sex, concomitant medical problems, and pharmacological therapy. In addition, because the diagnosis of early-stage dementia in DS is particularly difficult, we insisted that both controls and treated patients meet the criteria for middle-stage dementia before being enrolled in the study. We also showed that the rate of decline in cognitive performance prior to the institution of donepezil treatment did not differ in the treated group vs the control group.
Lott IT, Osann K, Nelson L, Doran E. Cognitive Decline in Down Syndrome—Reply. Arch Neurol. 2003;60(7):1024. doi:10.1001/archneur.60.7.1024-a