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AlzRisk Paper Detail

Reference: Scarmeas, 2006
Cohort: Washington Heights-Inwood Columbia Aging Project
Risk Factor: Dietary Pattern

Exposure Detail
Dietary habits were recorded at baseline using an interviewer-administered 61-item version of the Willett semi-quantitative food frequency questionnaire. Intake of food groups (dairy, meat, fruits, vegetables, legumes, cereals, and fish) was adjusted for caloric intake using the regression residual method (Willett W, Stampfer MJ. Total energy intake: implications for epidemiologic analyses. Am J Epidemiol 1986; 124:17-27).

A Mediterranean diet score was computed based on intake for nine different food categories. The Mediterranean diet score ranges from 0 to 9, with a higher score indicating stronger adherence to a Mediterranean diet. For those food categories thought to be beneficial (vegetables, fruits, legumes, cereals, fish, monounsaturated to saturated fat ratio), a 1 was assigned for intake at or above the sex-specific median level and a 0 otherwise. For those food categories thought to be harmful (meat, dairy), the scoring method was reversed. For alcohol, a 1 was assigned for intake between 0 to 30 grams/day and a 0 for no intake or for more than 30 grams/day.

Screening and Diagnosis Detail
Screening Method:
BDRSBlessed Dementia Rating Scale
CDRClinical Dementia Rating (Berg 1988) (CDR)
Neuropsych Testing

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-III-R.

"A consensus diagnosis for the presence or absence of dementia was made at a diagnostic conference of neurologists and neuropsychologists where information of all the above evaluations was presented. Evidence of cognitive deficit (based on the neuropsychological scores as described above), evidence of impairment in social or occupational function (as assessed by the Blessed Dementia Rating Scale, the Schwab
and England Activities of Daily Living Scale, and the physician’s assessment), and evidence of cognitive and social-occupational function decline compared with the past were the criteria used for the diagnosis of dementia as required by the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition(DSM-III-R). The type of dementia was subsequently determined. For the diagnosis of probable or possible AD, the criteria of the National Institute of Neurological and Communicative Disorders and Stroke - Alzheimer’s Disease and Related Disorders Association[40] were used."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

Follow-up time was the time scale in the proportional hazards analysis.

AD Covariates:
APOE4APOE e4 genotype
BMIbody mass index
Kcalcaloric intake
CIcomorbidity index
SMsmoking status

Note that a 1-point increase in the Mediterranean diet score corresponds to an approximately 0.5 increase in standard deviation of the score in this population.