Low Education Level Independently Increases Dementia Risk

Caroline Cassels

October 1, 2007 — Low levels of education appear to independently increase dementia risk regardless of other potential contributors, including demographic, socioeconomic, and vascular factors, new research suggests.
Results from the Cardiovascular Risk Factors, Aging and Dementia (CAIDE) study showed that, compared with individuals with the lowest levels of education, highly educated individuals had an 80% lower dementia risk.
"Generally speaking, people with low education levels seem to lead unhealthier lifestyles, which could suggest the 2 work concurrently to contribute to dementia or Alzheimer's disease, but our results showed a person's education predicted dementia on its own," said Tiia Ngandu, MD, PhD, of the Karolinska Institute in Stockholm, Sweden.
It might be that highly educated people have a greater cognitive reserve, which is the brain's ability to maintain function in spite of damage, making it easier to postpone the negative effects of dementia. Additionally, unhealthy lifestyles may independently contribute to the depletion of this reserve," Dr. Ngandu added.
The study is published in the October 2 issue of Neurology.
Methods
Derived from 4 separate independent population-based, randomly selected samples (from 1972, 1977, 1982, and 1987), the CAIDE study followed 1388 individuals from middle age to late life (an average of 21 years); they underwent re-examination in 1998.
During the mid-life examination, study participants filled out a self-administered questionnaire covering socioeconomic factors, health behavior, health status, and medical history. In addition, a venous blood sample was taken and systolic and diastolic blood pressure and height and weight were measured.
Information on education level was also gathered at the mid-life examination. Study subjects were categorized into 3 groups: those with 5 years of education or less (low); those with 6 to 8 years of education (medium); and those with 9 or more years of education (high).
Methods for the late-life examination were the same as those used in the mid-life exam. During this phase of the study, participants underwent ApoE genotyping and had their cognitive status assessed. Study subjects who scored 24 or less on the Mini-Mental State Examination (MMSE) were referred for further diagnostic examination.
A total of 61 individuals met the diagnosis of dementia. Of these, 48 had Alzheimer's disease.
Dose-Dependent Effect
"Education was associated with the risk of dementia in a dose-dependent manner. Compared with people with low education, those with medium education had a 40% lower risk of developing dementia, and those with high education had 80% lower risk for dementia," the authors write.
According to the investigators, adjustment for potential confounders/mediators, including demographic, socioeconomic, and vascular factors, as well as mid-life physical activity levels, ApoE status, and depression, did not change the results.
"Our study showed that Finnish people with medium to high education have a lower risk of dementia when compared with persons with a low education level. The confounding/mediating effects related to differences in socioeconomic, vascular, or lifestyle characteristics between people with different levels of education were taken into account. However, none of these factors changed the results, suggesting that the effect of education is independent of other risk factors for dementia," they write.
Investigators found that those in late life those with lower education at midlife had a higher occurrence of dementia and Alzheimer's disease.
The study was funded by the Alzheimer's Association, the Aging Program of the Academy of Finland, and Kuopio University Hospital in Finland.
Neurology. 2007; 69:1442-1450.