We agree with Prof Petersen in his Comment1 that the findings in our Article, which used CSF measures, and those of the Mayo Clinic Study of Aging (MCSA),3 which used imaging variables, together provide strong support for the construct of preclinical Alzheimer's disease (AD). As illustrated in Prof Petersen's figure, the frequencies of the stages as defined in the two studies are virtually identical. However, several inaccuracies in the Comment warrant correction to prevent misinterpretation of our data. Prof Petersen writes that we "state that participants are either normal (clinical dementia rating [CDR] 0), or have dementia (CDR >0.5); there is no predementia symptomatic state". This is untrue. We state "the global CDR stages are 0, indicating cognitive normality, and 0.5, 1, 2 and 3, indicating very mild impairment or very mild dementia, and mild, moderate, and severe dementia, respectively" (second paragraph, second page). We further state that "in individuals with a CDR score of 0.5, AD was diagnosed if a score of at least O.5 was given for memory and at least one other domain and the clinician deemed the cognitive impairments to be due to AD (probable AD; referred to as CDR 0.5, symptomatic AD)."
展开▼
