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Reference: Gray, 2008
Cohort: Adult Changes in Thought-Group Health Cooperative
Risk Factor: Nutritional Antioxidants


Average Follow-up Time Detail
We estimated average person-years of follow-up by multiplying the reported average follow-up time by the number of persons. In addition, this estimate pertains to the analysis of total dementia, but should be reasonably similar for the analysis of AD.

Exposure Detail
Assessed by in-person interview at baseline. Both vitamin C and multivitamins were assessed, but vitamin C use was defined as taking vitamin C-only supplements. Use was considered taking vitamin C supplements during at least one week of the previous month. The reference category consisted of those taking no supplemental vitamin C or E and no multivitamins.

Important Note: This table includes results for only 2 categories of vitamin C use, to the exclusion of participants in other categories (e.g., any vitamin E, any multivitamin use). Therefore, the percents shown do not add up to 100%.

Ethnicity Detail
"Other" ethnicities were not specified beyond not being Caucasian.

Screening and Diagnosis Detail
Screening Method:
CASICognitive Abilities Screening Instrument (Teng 1994)

AD Diagnosis:
NINCDS ADRDA National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association Criteria (McKhann 1984)

Total Dementia Definition: Dementia via DSM IV.

"Participants were rescreened using the CASI every 2 years to assess changes in cognitive function. Participants whose CASI scores fell below 86 underwent a standardized dementia diagnostic evaluation including a physical and neurological examination by a study neurologist, geriatrician, or internist and a 1-hour battery of neuropsychological testing. Relevant laboratory tests and brain computed tomography or magnetic resonance imaging studies were performed, or results were obtained from GHC records. Diagnoses were assigned at consensus diagnostic conferences using the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, criteria for dementia (12) and the criteria of the National Institute of Neurological and Communicative Disorders and Stroke and Alzheimer’s Disease and Related Disorders Association for AD (13). Participants with new-onset dementia underwent at least one annual follow-up examination for verification of dementia status. For these analyses, the two outcomes included any dementia and possible or probable AD."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

Age was the time scale in the proportional hazards analysis. Education was modeled as years of education.

AD Covariates:
Aage
Eeducation
Ggender
CHDcoronary heart disease
HShealth status
PAphysical activity
SMsmoking status

TD Covariates:
Aage
Eeducation
Ggender
CHDcoronary heart disease
HShealth status
PAphysical activity
SMsmoking status