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AlzRisk Paper Detail
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Reference: Cheng, 2011
Cohort: Washington Heights-Inwood Columbia Aging Project
Risk Factor: Diabetes Mellitus


Average Follow-up Time Detail
This study reports on the second cohort of enrolled participants in the WHICAP cohort, whose enrollment took place in 1999. Follow-up examinations were conducted approximately every 18 months, and continued until 2007.

The mean follow-up time was 3.9 years.

Exposure Detail
Diabetes status was determined from participants' self-reports of their type 2 diabetes (T2D) history and their use of diabetes medication.

"History of T2D was ascertained by self-report or by the use of diabetes medications at baseline and each follow-up visit."

Screening and Diagnosis Detail
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

"The diagnosis of dementia was established based on all available information gathered from the initial and follow-up assessments. Dementia was determined by consensus at a conference of physicians, neurologists, neuropsychologists and psychiatrists. The diagnosis of dementia was based on standard research criteria11 and required evidence of cognitive decline, including memory impairment, on the neuropsychological test battery as well as evidence of impairment in social or occupational function (clinical dementia rating 1 0.5)12 . The diagnosis of LOAD was based on the criteria of the National Institute of Neurological and Cognitive Disorders and Stroke/Alzheimer’s Disease and Related Disorders Association 13. A diagnosis of probable LOAD was made when the dementia could not be explained by any other disorder. A diagnosis of possible LOAD was made when the most likely cause of dementia was AD, but there were other disorders that could contribute to the dementia such as stroke and Parkinson’s disease."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

"Cox proportional hazard regression models16 were used to examine the association between T2D and dementia. Age at dementia onset was the time-to-event variable...A left censoring term for age at baseline was included in all models. The first model adjusted for gender alone, the second model adjusted for gender, ethnic group, education and APOE4 allele, and a third model adjusted for additionally hypertension, heart disease, non-HDL cholesterol, HDL cholesterol and history of stroke. The rationale for the first model was adjustment for common demographics."

AD Covariates:
Aage
Eeducation
Ggender
APOE4APOE e4 genotype
RErace/ethnicity

TD Covariates:
Aage
Eeducation
Ggender
APOE4APOE e4 genotype
RErace/ethnicity