Education and Net Worth May Guard Against Dementia, but not Mortality, in Elderly

A longituinal study funded by the National Institute on Aging suggests that cognitive impairment (CI) in the elderly is less likely in persons who have more years of education or greater net worth. The data were published online last month in the journal Alzheimer's & Dementia.

In individuals aged 70 years or older from the University of Michigan Health and Retirement Study, cognitive function was assessed over 2 years and compared between two cohorts from 1993 and 2002. After adjusting for age and sex differences, investigators found that higher education levels and net worth in the 2002 cohort accounted for approximately 40% of the group's decreased prevalence of CI (Table). The authors explain their findings, in part, by suggesting that a higher level of education is associated with the development of greater cognitive reserve in the setting of developing memory disorders, like Alzheimer's disease.

Variable	Cohort		P Value
	1993 (n = 7406)	2002 (n = 7104)
Mean age, years	77.5	77.8	.02
Mean education, years	11.0	11.8	.001
Mean net worth, 1993 $	179,000	284,000	.001
Cognitive function
Normal	87.8	91.3	.001
Mild CI	5.2	3.5	.001
Moderate/severe CI	7.0	5.2	.001

In both cohorts, the 2-year risk of mortality increased significantly with worsening CI (not surprising); however, the mortality risk in individuals with moderate or severe CI was higher in the 2002 cohort than in the 1993 group (adjusted-HR P = .09). In addition, lengthier education was associated with an increased mortality risk in those individuals with CI—a finding that was of greater magnitude in the 2002 cohort.

The authors attempt to explain this curious finding by suggesting that the brains of more educated individuals can sustain a greater load of dementia-causing brain pathology, before reaching a clinically important threshold. However, once this clinical threshold is reached, their cognitive decline is more precipitous, and their mortality risk is consequently greater.