Early-Life Cognitive Ability Predicts Late-Life Dementia Risk

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School grades early in life appear to correlate with dementia risk.
School grades early in life appear to correlate with dementia risk.

WASHINGTON — Better school performance at an early age may be an accurate predictor of the brain's ability to adapt to injuries that cause dementia later in life, according to two studies presented at the 2015 Alzheimer's Association International Conference.

“It appears that baseline cognitive ability — even at age 10 — may provide the foundation for successful cognitive aging much later in life,” said Serhiy Dekhtyar, PhD, of the department of clinical neuroscience at Karolinska Institutet in Stockholm, Sweden.

They examined data on childhood cognitive ability from a cohort of 7,574 people aged 65 years and older who participated in the Uppsala Birth Cohort Study along with dementia onset. During the 21-year follow-up period, 950 people were diagnosed with dementia. 

Participants with childhood school grades in the lowest 20% had a 21% greater risk for developing dementia, the Dekhtyar and colleagues found.

Although high occupational complexity in a field involving data and numbers reduced dementia risk by 23% (hazard ratio=0.77; P<0.05), it did not appear to compensate for the risk associated with low school marks. However, high school grades were associated with reduced dementia risk regardless of career complexity. 

The group with the lowest dementia risk was individuals with both higher childhood school performance and high occupational complexity. Dementia risk was 39% lower in those participants (HR=0.61; P<0.001). 

In a second study, Hui-Xin Wang, PhD, of the Aging Research Center also at Karolinska Institutet, confirmed the protective effects of early academic performance on later dementia risk. 

She and colleagues examined incident dementia rates with grades from age 9 to 10 that were extracted from school archives among a cohort of 440 participants aged 75 years and older who participated in the Kungsholmen project. 

They collected data on formal education and occupational complexity at baseline and the first follow-up examination. During the 9 year study period, 163 participants (37%) developed dementia. 

Again, participants who scored in the lowest 20% of school grades had a nearly twofold increase for dementia (relative risk=1.54; 95% CI: 1.03-2.29), even after adjusting for formal educational attainment and occupational complexity, the researchers found.

In that study, secondary education also appeared to protect against dementia (RR=0.72; 95% CI: 0.50-1.30), but not post-secondary and university education. 

Occupational complexity with data did not appear to be a strong predictor of dementia risk in this population; however, high complexity with people was protective, but only for women (RR=0.25; 95% CI: 0.06-1.06).

“These findings suggest that early-life cognitive ability may be an important predictor of dementia in late life,” said Wang.

References

  1. Dekhtyar S et al. #146. “Dementia Incidence in Inpatient Registers and MMSE Test Scores in a Clinical Study in Sweden.”  
  2. Wang HX et al. #146. “Childhood School Performance, Education, and Occupational Complexity.”

Both presented at: AAIC 2015. July 18-23, 2015. Washington, DC.

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