Relationship between complexity of main lifetime occupation and risk for Alzheimer's disease

Publishing in the September issue of the Journal of Gerontology: Psychological Sciences, University of South Florida School of Aging Studies researcher Ross Andel and James Mortimer, professor, USF College of Public Health, examined the relationship between complexity of main lifetime occupation and risk for Alzheimer's disease and dementia in general. He and co-researchers discovered that people engaging in "complex work" had a reduced risk of dementia and Alzheimer's disease.

"Occupations with high mental demands may provide a form of ‘mental exercise' that supports brain function into older adulthood," said Andel.

Recent research has focused on lifestyle issues – such as smoking, drinking, exercise and leisure activities – and the roles they may play in the risk for dementia and Alzheimer's disease. Occupation as an intellectual stimulus, said Andel, is yet another factor that needs consideration, particularly given the amount of time people spend at work. While occupational classification has been a previously studied variable, and occupations with low social status have been found to be a risk factor for dementia and Alzheimer's disease, occupational complexity as a source of intellectual stimulation has not been looked at sufficiently.

Andel and his co-researchers studied risk of dementia in cases and controls and in complete twin pairs using data from a Swedish Twin Registry, through which sets of twins were followed for more than 40 years and whose main occupations were recently recorded. Within the twin pairs, one twin was diagnosed with dementia and the co-twin was dementia-free. The sample included 10,079 members of a subset of the Swedish Twin Registry called the Study of Dementia in Swedish Twins (HARMONY), a study led by Margaret Gatz from the University of Southern California.

The authors found that those who performed complex work with data or people had lower risk of dementia and Alzheimer's disease.

"Those performing complex work with people, such as speaking to, instructing or negotiating with people, appeared particularly protected in this sample,"Andel said.

Results were adjusted for gender, level of education and, in case-control analyses, for age.

"Our results suggest that intellectually demanding activity at work may facilitate brain health in old age," concluded Andel. "However, further research is needed to understand why complex work appears to offer a buffer against dementia and whether occupational complexity is protective independent of occupational status."