This GWAS dataset was used in the discovery stage of the ADGC Naj et al. meta-analysis from 2011. It is one of the ten cohorts assembled by ADGC to identify genetic variants in LOAD.
The Adult Changes in Thought (ACT) study is a longitudinal prospective cohort study that began in 1994. Participants are randomly selected from Seattle area members of Group Health aged 65 years or older. Participants are cognitively intact at study enrollment, defined operationally as a CASI (Cognitive Abilities Screening Instrument) score of >85 or consensus diagnosis of "not demented" following comprehensive neurological and neuropsychological assessment. Incident cases of dementia are identified with the same 2-stage sampling scheme, where all participants with CASI scores <86 are evaluated with a comprehensive neurological and neuropsychological assessment, and all results are considered at a consensus conference.
Genetic Differences (GenDiff) was an epidemiologic case control study. Cases were newly recognized (e.g, "incident") "Probable AD" (McKhann criteria NINCDS-ADRDA). Subjects were discovered and diagnosed by the Alzheimer's Disease Patient Registry from a community based HMO. Controls were selected at random from the same HMO, without cognitive impairment, and frequency matched for age and sex. They were also cognitively screened and followed. Genetic Differences was funded through R01 AG007584.
This dataset was generated in 2009. While ACT is continutally enrolling subjects, Genetic Differences has completed enrollment.
Detailed information about the dataset is provided in the following document: NG00034_ACT_GenDiff_README.txt