WASHINGTON ― Children who get good grades in school and eventually work in complex jobs involving data and numbers may be protected from getting dementia later in life, according to new research from Sweden.
"Childhood school grades, which we used in our study as a marker of early-life cognitive abilities, are related to dementia risk more than 50 years later in life, which is truly remarkable. We also find that continued intellectual engagement can further postpone dementia incidence," said Serhiy Dekhtyar, PhD, from the Department of Clinical Neuroscience, Karolinska Institutet, Stockholm.
The investigators followed 7574 individuals aged 65 years and older from the Uppsala Birth Cohort Study for more than 20 years. They had information on childhood school grades at age 10 years, as well as educational and occupational attainment.
"We ended up with a full life-course model of cognitive reserve in dementia, with childhood cognitive ability, early-adulthood education, and mid-life occupational attainment, which has never been tested before," Dr Dekhtyar said in a statement.
The results were presented here at the Alzheimer's Association International Conference (AAIC) 2015.
During the study period, 950 participants developed dementia. Those with the lowest school grades (lowest 20%) at age 10 years had a 21% higher risk of developing dementia later in life (hazard ratio [HR], 0.79; P < .05).
People working in occupations in mid-life that required expertise with numbers and data had a 23% lower risk for dementia in old age (HR, 0.77; P < .05).
Childhood cognitive abilities remained associated with dementia after accounting for education and occupational complexity. "It seems that education and occupational complexity cannot compensate for the effect of low baseline abilities. We found that the risk of dementia was similar in people who had low grades irrespective of their subsequent occupation or educational attainment," Dr Dekhtyar said during a press briefing.
The lowest dementia risk (39% reduction) was found in individuals with both higher childhood grades and data-rich occupations (HR, 0.61; P < .001).
Cognitive Reserve Starts Early
Related research reported by Hui-Xin Wang, PhD, from the Karolinska Institutet and Stockholm University, corroborate Dr Dekhtyar's findings. Dr Wang and colleagues followed a cohort of 440 men and women aged 75 years and older in the Kungsholmen project, a multifaceted research program on aging and dementia. All participants were cognitively healthy at the outset. The researchers had data on school grades at age 9 or 10 years as well as on educational and occupational attainment.
Several significant correlations between grades and dementia risk emerged. The risk for dementia was elevated more than 50% in individuals older than 75 years who had the lowest early-life school grades (relative risk [RR], 1.54; 95% confidence interval [CI], 1.03 - 2.29), even if they had more formal education or a complex job.
Individuals who completed secondary education had a lower risk for dementia (RR, 0.72; 95% CI, 0.50 - 1.03) relative to those who only completed elementary education. Working in a data-rich job was a weak predictor of dementia risk, although a high complexity of work with people (eg, high demands on negotiating, instructing, and supervising) was protective in women (RR, 0.25; 95% CI, 0.06 - 1.06). The results held after accounting for genetic susceptibility (APOE e4 status), comorbidities, and depressive symptoms.
"From our study, we can see that early-life cognitive ability is a foundation for later-life cognitive aging. The study suggests that cognitive reserve starts early and is accumulating during the whole life course," Dr Wang told Medscape Medical News.
Commenting on the findings for Medscape Medical News, Maria Carrillo, PhD, chief science officer for the Alzheimer's Association, said the studies "add to what we are learning about how early-life experiences impact later-life risk for Alzheimer's. The brain is something that we don't really think about much. Especially when you're younger, you think about building muscle, and the brain is the last organ you think about, but it really is the most important one."
"Once an adult, I can't change my childhood, but what I can do today is try to be as active as possible and keep my mind as sharp as possible. But we should also think about our children and grandchildren. They should be as actively engaged as possible not only in school but in extracurricular activities. That's really the bottom line. Lifelong experiences actually impact brain development and your risk for dementia," Dr Carrillo said.
The studies had no commercial funding. The authors and Dr Carrillo report no relevant financial relationships.
Alzheimer's Association International Conference (AAIC) 2015. Abstracts O2-11-03 and O2-11-04. Presented July 20, 2015.
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Cite this: Good Elementary School Grades Linked to Lower Dementia Risk - Medscape - Jul 20, 2015.