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Neurology. 2002 Jan 22;58(2):209-18.

Incidence of AD may decline in the early 90s for men, later for women: The Cache County study.

Author information

1
Department of Mental Hygiene, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, MD 21205, USA.

Abstract

OBJECTIVES:

To characterize the incidence of AD among the elderly population of Cache County, UT, noted for its longevity and high response rates; to explore sex differences; and to examine whether AD incidence plateaus or declines in extreme old age.

METHODS:

Using a multistage screening process in 1998 and 1999, and re-examining 122 individuals who had been identified 3 years earlier as cognitively compromised but not demented, the authors found 185 individuals with incident dementia (123 with AD) among 3,308 participants who contributed 10,541 person-years of observation. Adjusting for nonresponse and screening sensitivity, the authors estimated the incidence of dementia and of AD for men and women in 3-year age intervals. Multivariate discrete time survival analysis was used to examine influences of age, sex, education, and genotype at APOE, as well as interactions of these factors.

RESULTS:

The incidence of both dementia and AD increased almost exponentially until ages 85 to 90, but appeared to decline after age 93 for men and 97 for women. A statistical interaction between age and the presence of two APOE-epsilon 4 alleles indicated acceleration in onset of AD with this genotype; the interaction of age and one epsilon 4 suggested more modest acceleration. A statistical interaction of sex and age indicated greater incidence of AD in women than in men after age 85.

CONCLUSIONS:

The incidence of AD in the Cache County population increased with advancing age, but then peaked and declined among the extremely old. The presence of APOE-epsilon 4 alleles accelerated onset of AD, but did not appreciably alter lifetime incidence apparent over a span of 100 years.

PMID:
11805246
DOI:
10.1212/wnl.58.2.209
[Indexed for MEDLINE]

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