March 11, 2008 — Adult-age offspring of
parents who have both been diagnosed with Alzheimer’s disease appear to
have an increased risk of developing the disease compared with the
general population, according to a new report.
"Alzheimer’s disease is a common cause of dementia in the U.S.
population and the leading cause of cognitive impairment in the elderly
population," according to background information in the article.
Identifying genes in Alzheimer’s disease patients can help detect
others who are at risk for the condition. "Because Alzheimer’s disease
is so common in the general population, it is not uncommon for both
spouses to develop the disease. Offspring of two such affected
individuals would presumably carry a higher burden of these Alzheimer’s
Suman Jayadev, M.D., of the University of Washington, Seattle, and
colleagues studied the frequency of Alzheimer’s disease in adult
children of 111 families in which both parents had been clinically
diagnosed with the disease. Ages at onset of dementia were also noted.
Of the 297 offspring who reached adulthood, 22.6 percent developed
Alzheimer’s disease compared with an estimated 6 percent to 13 percent
of the general population. The average age at onset for children of
couples with the illness was 66.3. The risk of developing the disease
increased with age with 31 percent of those older than age 60 affected
and 41.8 percent of those older than age 70 affected. "Of the 240
unaffected individuals, 189 (78.8 percent) had not yet reached age 70
years, suggesting that the incidence of Alzheimer’s disease (22.6
percent) is an underestimation of the final incidence rate of
Alzheimer’s disease in this population," the authors write.
Having additional family members with Alzheimer’s disease did not
increase the risk of developing the disease, but was associated with a
younger age at onset for those who did develop the illness. Children
with no history of the disease beyond the parents had an older age at
onset (72 years) compared with those who had one parent with family
history of the disease (60 years) or both parents with family history
of the illness (57 years).
"The role of family history and the specific genes involved in this
phenomenon require a better definition," the authors conclude.
"Families with a significant Alzheimer’s disease history may be more
likely to be referred to an Alzheimer’s disease research center and,
thus, the present patients may be ‘enriched’ for a particularly
Alzheimer’s disease-prone subgroup. Following these families as the
offspring continue to age will provide increasingly informative data."
Journal reference: Arch Neurol. 2008;65:373-378.
This study was supported by grants from the National Institute on
Aging/National Institutes of Health and by Veterans Affairs research
Source : JAMA and Archives Journals