A Life-Course Study of Cognitive Reserve in Dementia--From Childhood to Old Age.
OBJECTIVE
To test a life-course model of cognitive reserve in dementia and examine if school grades around age 10 years, formal educational attainment, and lifetime occupational complexity affect the risk of dementia in old age.


METHODS
7,574 men and women from the Uppsala Birth Cohort Multigenerational Study were followed for 21 years. Information on school performance, formal education, and occupational attainment was collected prospectively from elementary school archives and population censuses. Dementia diagnosis was extracted from the two Swedish registers. Discrete-time Cox proportional hazard models were estimated.


RESULTS
Dementia was diagnosed in 950 individuals (12.5%). Dementia risk was lower among individuals with higher childhood school grades (hazard ratio [HR]: 0.79; 95% confidence interval [CI]: 0.68 to 0.93) and was lower among individuals in data-complex occupations (HR: 0.77; 95% CI: 0.64 to 0.92). Professional/university education predicted lower risk of dementia in minimally adjusted models (HR: 0.74; 95% CI: 0.60 to 0.91), although the effect faded with adjustment for occupational complexity. Lowest risk was found in the group with both higher childhood school performance and high occupational complexity with data (HR: 0.61; 95% CI: 0.50 to 0.75). Importantly, high occupational complexity could not compensate for the effect of low childhood grades. In contrast, dementia risk was reduced in those with higher school grades, irrespective of occupational complexity.


CONCLUSIONS
Higher childhood school performance is protective of dementia risk, particularly when preserved through complex work environments in adulthood, although it will remain protective even in the absence of later-life educational or occupational stimulation.
Department of Clinical Neuroscience, Section of Psychology, Karolinska Institutet and Stockholm University, Stockholm, Sweden. Electronic address: serhiy.dekhtyar@ki.se.
Serhiy
S
Dekhtyar
Aging Research Center, Department of Neurobiology, Care Sciences, and Society, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
Hui-Xin
HX
Wang
Centre for Economic Demography and Department of Economic History, Lund, Sweden.
Kirk
K
Scott
Faculty of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK.
Anna
A
Goodman
Centre for Health and Equity Studies, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
Ilona
I
Koupil
Department of Clinical Neuroscience, Section of Psychology, Karolinska Institutet and Stockholm University, Stockholm, Sweden.
Agneta
A
Herlitz
D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000523:psychology*; D058245:Cognitive Reserve; D003704:Dementia / Q000175:diagnosis / Q000453:epidemiology / Q000523:psychology*; D004522:Educational Status; D005260:Female; D006801:Humans; D008297:Male; D009790:Occupations; D012042:Registries; D012307:Risk Factors; D013548:Sweden / Q000453:epidemiology
Dementia; cognitive reserve; life course