Get Newsletter
AlzRisk Paper Detail

Reference: Zandi, 2004
Cohort: Cache County Study
Risk Factor: Nutritional Antioxidants

Exposure Detail
"At the initial visit of wave I, we administered a standardized interview covering suspected risk factors for dementia. The interview included sections on sociodemographic factors including education, occupational history, medical history, tobacco and alcohol use, and medication use. The section on medications asked participants about use during the preceding 2 weeks of any prescription or over-the-counter medications, including vitamin supplements. Interviewers then asked to see the containers of these treatments, and recorded information about the use of each. We categorized participants according to their use of vitamin supplements, counting individuals as vitamin E users if they reported taking an individual supplement of vitamin E or a multivitamin preparation that contained more than 400 IU of vitamin E. Similarly, vitamin C users reported taking vitamin C supplements or multivitamin preparations containing at least 500 mg of ascorbic acid. Individuals classified as multivitamin users reported similar use of a multivitamin preparation containing lower doses of vitamin E or C. Finally, we classified individuals as users of vitamin B formulations if they took a supplement preparation that specifically contained a complex of multi-B vitamins (riboflavin, pyridoxine, cyanocobalamin, etc). We examined B vitamins and multivitamins as 'control' exposures to assess the specificity of any association between use of higher doses of antioxidant supplements and risk of AD, and to differentiate this association from a tendency toward supplement use in general."

Ethnicity Detail
Not reported in this paper. All participants were residents of Cache County, Utah, USA. Ethnicity information based on a description of the cohort.

Age Detail
Age at start of follow-up was derived from a table describing the companion prevalence study, and therefore the true mean age for the incidence study is probably younger.

Screening and Diagnosis Detail
Screening Method:
DQDementia Questionnaire (Silverman 1986)
3MSEModified Mini-Mental State Examination (Teng 1987)

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

"...screening began with an interview that included the modified Mini-Mental State Examination (3MS) (22,23) or, for those unable to participate, a questionnaire administered to a collateral informant (24). Individuals who did poorly on this screen (eg, scoring <87 on the 3MS at wave I) were examined further by telephone interview with a collateral informant by means of the Dementia Questionnaire (DQ) (25). All those older than 90 years plus a weighted stratified subsample of 19% of all participants were also studied with the DQ, regardless of their initial screening results. Participants with DQ scores of 4 or more at wave I or 3 or more at wave II, as well as all members of the 19% subsample, were then examined at their place of residence. The examination included a medical history, a chronologic history of cognitive symptoms, and a structured neurologic examination, all administered by specially trained nurses, and a 1-hour battery of neuropsychological tests administered by psychometric technicians. A geriatric psychiatrist (J.C.S.B.) and neuropsychologist (J.T.T.) reviewed these data and assigned working diagnoses of dementia (Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition (26) or other cognitive syndromes. Participants with working diagnoses of prevalent or incident dementia were further examined by a geriatric psychiatrist (J.C.S.B.) and were referred for laboratory studies including neuroimaging. These and other participants with apparent cognitive compromise received an identical clinical assessment 18 months later to assess longitudinal course. A consensus panel of experts in neurology, geriatric psychiatry, neuropsychology, and cognitive neuroscience then reviewed all available data and assigned final differential diagnoses. Diagnoses of AD used standard criteria (27) while diagnoses of other dementing illnesses were also made according to current research practice (20,21)."

Covariates & Analysis Detail
Analysis Type:
Logistic regression

Discrete-time survival analysis using logistic regression.

Also adjusted for "the squared deviation of age from the population median" and the interaction between APOE e4 and age.

AD Covariates:
APOE4APOE e4 genotype
HShealth status