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AlzRisk Paper Detail

Reference: Yang, 2011
Cohort: Saint Louis ADRC Cohorts
Risk Factor: Blood Pressure

Average Follow-up Time Detail
All participants were members of longitudinal studies of dementia and healthy aging at the Alzheimer Disease Research Center in St. Louis, Missouri between April 1990 and February 2005. "All participants were examined annually unless prevented by death, refusal, or relocation."

"The mean follow-up time was 6.7 years (SD: 5.3, 95%CI: 6.2-7.1) for all participants, 5.9 years (SD: 4.9, 95%CI: 5.4-6.3) for participants with a CDR score of 0 and 9.2 years (SD: 5.6, 95%CI: 8.2-10.1) for participants developing AD."

Exposure Detail
At each study visit, participants were asked to report if they had ever been diagnosed with hypertension - the response to this question at the first study visit is used to determine whether a person had a history of hypertension at baseline.

Blood pressure was also measured once at each study visit. "Measurements were taken at the right upper arm with an appropriately sized cuff and aneroid sphygmomanometer after the patient had been resting for approximately 15 minutes."

"Pulse pressure was defined as the difference between SBP and DBP, and MAP as DBP + 1/3*PP."

Screening and Diagnosis Detail
Screening Method:
CDRClinical Dementia Rating (Berg 1988) (CDR)
Informant interview

AD Diagnosis:
DSM IIIR Diagnostic and Statistical Manual III-Revised
NINCDS ADRDA National Institute of Neurological and Communicative Diseases and Stroke/Alzheimer's Disease and Related Disorders Association Criteria (McKhann 1984)

"At entry and at annual follow-up, experienced clinicians assessed each participant for the presence and severity of dementia based on semistructured interviews with the research participant and a knowledgeable collateral source (usually a spouse or adult child), followed by a neurological and physical examination of the participant. The assessment protocol evaluated cognitive problems that represented a decline from a former level of function for that individual and that interfered to at least some degree with the individual’s ability to carry out accustomed activities. The clinical diagnosis of AD was made in accordance with the standard criteria (Diagnostic and statistical Manual of Mental Disorders-Third Edition-Revised) [DSM-III-R] and 32 National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer’s Disease and Related Disorders Association [NINCDS-ADRDA]33).
The protocol included assignment of a Clinical Dementia
Rating (CDR)34 by the examining clinician."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

All associations between dementia and continuous blood pressure measures were originally reported in 1 mm Hg increments. They have been converted to the association for a 10 mm Hg increment.

AD Covariates:
APOE234APOE e2 e3 e4 genotype