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AlzRisk Paper Detail

Reference: Zandi, 2005
Cohort: Cache County Study
Risk Factor: Statin use

Exposure Detail
Investigators ascertained exposure information via visual inventory of medications at baseline ("wave 1") and at follow-up visits, approximately 3 years later ("wave 2"). This entry pertains to results at wave 2.

The investigators compared incident AD risk in two groups: the group of participants who used statins at wave 2 ("Currently uses") and the reference group of participants who did not use statins or other LLAs at wave 2 ("Does not use").

Ethnicity Detail
The Cache County cohort was predominantly Caucasian (99%).

Age Detail
The mean age of the cohort including those with baseline dementia was 75.5 (7.1) years. The article did not provide the mean age of participants who were free of dementia at the start of follow-up.

Screening and Diagnosis Detail
Screening Method:
"Modified" 3MSE"Modified" Modified Mini-Mental State Examination (Tschantz 2002)
DQDementia Questionnaire (Silverman 1986)
Informant interview
IQ-CODEInformant Questionnaire for Cognitive Decline in the Elderly (Jorm 1989)
Neuropsych Testing

AD Diagnosis:
Brain Imaging
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)
Neuropsychological examination

Total dementia definition: Dementia via DSM-IIIR

"We used a multistage screening and assessment protocol to identify and diagnose prevalent cases of dementia at wave 1 and incident cases at wave 2. Procedures have been described in detail elsewhere. Briefly, screening for dementia began with an in-person interview that included an adaptation of the Modified Mini-Mental State examination (3MS) or, for those unable to participate, the Informant Questionnaire on Cognitive Decline in the Elderly administered to a collateral informant. Participants who scored beyond predetermined cutpoints on these tests (at wave 1, <87 on the 3MS or ≥3.27 on the Informant Questionnaire; at wave 2, <84 on the 3MS for those aged 80 years or older, or a decline of >3 points from the wave 1 score on the 3MS) were evaluated further by interviewing collateral informants with the Dementia Questionnaire. Dementia Questionnaire interviews were also administered to a 19% stratified validation subsample of high-risk participants (stratified by age, sex, and number of APOE 4 alleles, with weighting toward strata with older participants with 1 or, especially, 2 4 alleles), regardless of their results on the 3MS or Informant Questionnaire. Participants whose screening results suggested cognitive difficulties, as well as all members of the validation subsample, were then examined by specially trained nurses and psychometric technicians. The examination included a brief physical assessment, a detailed chronological history of medical and cognitive symptoms, a structured neurological examination, and a 1-hour battery of neuropsychological tests. A geriatric psychiatrist and neuropsychologist reviewed these data with the field assessment team and assigned working diagnoses of dementia (DSM-III-R) or other cognitive syndromes. Living participants with working diagnoses of dementia were then examined in person by a geriatric psychiatrist or neurologist and referred for laboratory studies, including neuroimaging. To substantiate or refine their diagnoses, we reexamined these individuals 18 months after their initial evaluations. A consensus panel of experts in neurology, geriatric psychiatry, neuropsychology, and cognitive neuroscience then reviewed all available data and assigned final diagnoses.
Diagnoses of AD followed the criteria of the National Institute of Neurological and Communicative Disorders and Stroke–Alzheimer’s Disease and Related Disorders Association. Other dementing illnesses were also diagnosed using current research criteria. Onset was defined as the year in which a participant unambiguously met diagnostic criteria for dementia. All evaluations and diagnoses were made without knowledge of the participants’ use of statins or other risk factors, including APOE genotype."

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

AD Covariates:
Age*APOE4Age*APOE4 interaction
APOE4APOE e4 genotype
DMdiabetes mellitus
HXHTNhistory of hypertension

TD Covariates:
Age*APOE4Age*APOE4 interaction
APOE4APOE e4 genotype
DMdiabetes mellitus
HXHTNhistory of hypertension