Education is associated with level of cognitive function but does not affect the rate of cognitive decline, according to a study in the February 3 Neurology.
Robert S. Wilson, PhD, Senior Neuropsychologist of the Rush Alzheimer’s Disease Center at Rush University Medical Center in Chicago, and colleagues analyzed 6,533 people (mean age, 72.2) who completed a mean of three interviews during a mean of 6.5 years. Subjects had a mean of 12.2 years of formal education. Cognition was assessed with use of the Mini-Mental State Examination.
Higher education was associated with younger age and white race but not with gender. The mean baseline composite measure of global cognition was 0.24. When the effects of time and time squared (to allow for nonlinear change in cognition) were analyzed, cognition declined at a gradually accelerating rate.
In analyses that controlled for age, gender, and race, higher level of education was associated with higher level of cognition at baseline. However, patients with different levels of education did not differ in rate of cognitive decline. Similar results were observed after adjustments for income and lifetime occupation.
The analysis was repeated with four additional terms—the interaction of education with time squared, a quadratic term for education, and terms for its interactions with time and time squared. In this model, “rates of cognitive change are broadly similar, but those with low education (eight years, 10th percentile) appear to be declining slightly less than persons with average (12 years, 50th percentile) or high (16 years, 90th percentile) levels of education but only in the early years of follow-up,” noted the study authors. There was a slight benefit of higher education in later years. Results were unchanged after controlling for heart disease, hypertension, stroke, diabetes, and cancer. In addition, the association between education and change in cognitive function did not vary by race.
Exclusion of patients at or below the 10th, 20th, and 30th percentiles in cognitive score showed that higher education was associated with slightly less rapid cognitive decline early in follow-up. However, higher education was associated with slightly more rapid decline later in follow-up. Furthermore, cognitive function improved with repeated test administration, although these effects were not associated with education.
“Because results are based on a measure of global cognition, we cannot rule out the possibility that education is related to decline in some cognitive domains but not others,” the study authors noted.
—Marguerite Spellman