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AlzRisk Paper Detail

Reference: Gatz, 2006
Cohort: Study of Dementia in Swedish Twins
Risk Factor: Physical Activity

Average Follow-up Time Detail
There were 98 monozygotic co-twin pairs in this analysis. The control group consists of related (internal) controls (i.e., nondemented twin partners to the twins with dementia). Participants were all monozygotic pairs in either cohort in which one was diagnosed with dementia and the other was determined to be nondemented, at least one member of the pair was alive in 1998, and the nondemented twin survived at least until the age of onset of dementia in the demented twin.

Exposure Detail
"Assessment of engaged midlife lifestyle was based on a
list of leisure activities in the 1967 questionnaire collected from the older cohort only; for each activity respondents indicated whether they participated before age 40. Everyone was over age 40 when asked this question;...

"Physical exercise was assessed for both cohorts. The response options reflected four levels of intensity. A dichotomous variable was created by dividing into 'hardly any' and 'light' exercise compared with 'regular' and 'hard.'"

This paper and the paper by Andel et al, 2003, also in this table, both evaluated participants from the HARMONY cohort. This paper reported results on 2 categories of physical activity and adjusted for 2 other factors, while Andel et al reported on 4 categories of physical activity and adjusted for 8 other factors.

Ethnicity Detail
No data on ethnicity was reported, however all participants reside in Sweden.

Age Detail
All participants in the HARMONY study were at least 40 when assessed for physical activity and at least 65 when screening began for AD and dementia.

Screening and Diagnosis Detail
Screening Method:
BDRSBlessed Dementia Rating Scale
TELETelephone assessment of dementia

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 diagnosis: DSM-IV

Vascular dementia diagnosis: NINDS-AIREN

Covariates & Analysis Detail
Analysis Type:
Conditional logistic regression

"In the co-twin control analyses, we obtained odds ratios from conditional logistic regression, using twin pair as a stratification variable [22]. These odds ratios reflect the ratio between the number of pairs in which the case is more often exposed and the number of pairs in which the control is more often exposed...

"Age and sex were controlled for by design in co-twin control analyses with same sex pairs...

"Odds ratio based on pairs discordant for dichotomous risk variable."

When considering physical activity as an ordinal variable, CASE>CONTROL compared with CASE
AD Covariates:

TD Covariates: