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AlzRisk Paper Detail

Reference: Ruitenberg, 2001
Cohort: Rotterdam Study/Gothenburg H-70 Study Combined
Risk Factor: Blood Pressure

Average Follow-up Time Detail
The Rotterdam Study recruited participants ages 55 and older, including institutionalized persons. Baseline examinations occurred between 1990 and 1993. Among those dementia-free at baseline (n=6,668), 5,468 completed a follow-up examination in 1993 or 1994. Proxies provided information on deceased participants and those who did not complete a second examination. The average follow-up time was 2.1 years.

The H-70 Study invited all 85-year-old persons, community-dwelling or institutionalized, currently residing in Gothenburg, Sweden in 1986-1987, to participate in a health survey. A subsample of these participants was recruited for a neuropsychiatric examination. Of the 347 participants who participated in this neuropsychiatric examination who were dementia-free at baseline, 188 completed a follow-up examination, 73 were deceased, and 86 refused a second examination. Information on those who were deceased or refused a second examination was obtained from medical records and other sources, and sufficient information for analysis was obtained on 320 persons. Average follow-up time was 2.2 years.

Exposure Detail
Blood pressure and antihypertensive medication use were assessed at the baseline examination. Participants were considered to be under treatment if they were currently taking antihypertensive medication at the baseline assessment.

"In the Rotterdam Study blood pressure was measured in the sitting position at the right upper arm with a random-zero sphygmomanometer. The average of two measurements, separated by a count of the pulse rate, was used in the analysis. During an interview at home a trained research assistant registered the current drug consumption. Of institutionalised participants, medication was reported by the medical staff. In the H-70 Study, blood pressure was measured in the sitting position at the right upper arm after 5 min of rest using a mercury manometer. Systolic and diastolic blood pressures were registered to the nearest 5mm Hg. During a house call, a registered nurse made a record of the prescribed and actually taken medication.23"

Ethnicity Detail
According to other descriptions of the cohort, all participants of the Rotterdam Study were residents of Rotterdam, The Netherlands. All participants of the Gothenburg H70 Study were residents of Gothenburg, Sweden. No other information on ethnicity or race has been reported.

Screening and Diagnosis Detail
Screening Method:
CAMDEXCambridge Examination for Mental Disorders of the Elderly
GMSGeriatric Mental State Schedule (Copeland 1976)
MMSEMini-Mental State Examination (Folstein 1975)

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

Dementia Diagnosis: DSM-III-R

The Rotterdam Study applied a three step screening approach to dementia diagnosis. Ott et al., 1995 provided a description of this process: "The brief cognitive test for dementia comprised a combined minimental state examination6 and geriatric mental state schedule (GMS-A, organic level).7 The test was administered by trained research assistants. Screen positive subjects had a minimental state examination score of 25 or less or a geriatric mental state score of 1 or more. Screen positive subjects were subsequently examined by a physician with the CAMDEX (Cambridge examination for mental disorders of the elderly) diagnostic interview,8 which included an interview with an informant. Participants who scored less than 80 on the CAMDEX cognitive test or who had higher scores but were suspected of dementia clinically were asked to participate in a third, extensive examination. In this diagnostic phase they were examined by a neurologist, had a brain scan (by magnetic resonance imaging), and were tested by a neuropsychologist...Dementia was diagnosed according to the American Psychiatric Association's criteria (DSM-III-R).11 The subdiagnosis of Alzheimer's disease was based on criteria produced by the National Institute of Neurological and Communicative Disorders and Stroke and the Alzheimer's Disease and Related Disorders Association.12 Both possible and probable cases of Alzheimer's disease were grouped in this category."

The H-70 Study utilized in-person, proxy interviews, and the MMSE. Dementia was diagnosed using DSM-III-R criteria while AD was diagnosed using NINCDS ADRDA criteria. Dementia diagnosis required symptom duration of 6 months.

Covariates & Analysis Detail
Analysis Type:
Cox proportional hazards regression

"Heretogeneity between the Rotterdam Study and the Gothenburg H-70 Study with regard to the relation between blood pressure and dementia was tested using an interaction term for blood pressure and place of residence. Because this interaction term was non-significant (p=0.54), we were able to pool the data on subjects aged 85 and over from the two studies, adding an indicator for place of residence."

AD Covariates:
SPstudy population

TD Covariates:
SPstudy population