The cross-sectional study included a total of 1,870 individuals (1,510 family members and 360 spouse controls) recruited through the Long Life Family Study. The main outcome measure was the prevalence of cognitive impairment based on a diagnostic algorithm validated using the National Alzheimer's Coordinating Center data set.
According to study results, the cognitive algorithm classified 546 individuals (38.5 percent) as having cognitive impairment consistent with Alzheimer disease. Long Life Family Study probands had a slightly but not statistically significant reduced risk of cognitive impairment compared with spouse controls (121 of 232 for probands versus 45 of 103 for spouse controls), whereas Long Life Family Study sons and daughters had a reduced risk of cognitive impairment (11 of 213 for sons and daughters versus 28 of 216 for spouse controls). Restriction to nieces and nephews in the offspring generation attenuated this association (37 of 328 for nieces and nephews versus 28 of 216 for spouse controls).
"Overall, our results appear to be consistent with a delayed onset of disease in long-lived families, such that individuals who are part of exceptionally long-lived families are protected but not later in life," the study concludes.
Published online May 6, 2013. doi:10.1001/.jamaneurol.2013.1959. Available pre-embargo to the media at http://media.jamanetwork.com.)
Editor's Note: This study was supported by grants from the National Institute on Aging and the American Federation of Aging Research. Please see the articles for additional information, including other authors, author contributions and affiliations, financial disclosures, funding and support, etc.