Job demands and dementia risk among male twin pairs.
BACKGROUND
Job characteristics may influence dementia risk, but some types of job complexity remain to be examined. Twin studies provide a useful methodology to examine job differences between pairs who share many environmental and genetic influences.


METHODS
Members of the NAS-NRC Twins Registry of World War II Veterans received a clinical evaluation for dementia and had job ratings from the Dictionary of Occupational Titles.


RESULTS
Cotwin-control models (n = 220 pairs) indicated lower dementia risk with greater job demands of reasoning, mathematics, language, and vocational training, with comparable results in case-control models (n=425 cases). These effects were significant among twin pairs discordant for 6 or more years, but not among those discordant between 3-5 years. Results were similar for Alzheimer's disease, and main effects were not further explained by zygosity or apolipoprotein E genotype.


CONCLUSIONS
Jobs that utilize data, academic skills, and extensive vocational training may protect against dementia; however, in twin pairs these effects only emerged among individuals who remained free of dementia several years after onset in their sibling.
Potter
Guy G
GG
Department of Psychiatry and Behavioral Sciences, Duke University Medical Center, Durham, NC, USA. guy.potter@duke.edu
Helms
Michael J
MJ
Burke
James R
JR
Steffens
David C
DC
Plassman
Brenda L
BL