Abstract
Evidence of the association between global cognitive function and mortality is much, but whether specific cognitive function is related to mortality is unclear. To address the paucity of knowledge on younger populations in the US, we analyzed the association between specific cognitive function and mortality in young and middle-aged adults. We analyzed data from 5,144 men and women between 20 and 59 years of age in the Third National Health and Nutrition Examination Survey (1988–94) with mortality follow-up evaluation through 2006. Cognitive function tests, including assessments of executive function/processing speed (symbol digit substitution) and learning recall/short-term memory (serial digit learning), were performed. All-cause mortality was the outcome of interest. After adjusting for multiple variables, total mortality was significantly higher in males with poorer executive function/processing speed (hazard ratio (HR) 2.02; 95% confidence interval 1.36 to 2.99) and poorer recall/short-term memory (HR 1.47; 95% confidence interval 1.02 to 2.12). After adjusting for multiple variables, the mortality risk did not significantly increase among the females in these two cognitive tests groups. In this sample of the US population, poorer executive function/processing speed and poorer learning recall/short-term memory were significantly associated with increased mortality rates, especially in males. This study highlights the notion that poorer specific cognitive function predicts all-cause mortality in young and middle-aged males.
Highlights
Low cognitive function, a state that involves problems with memory, learning, thinking, language, complex attention, and executive function, has been associated with cardiovascular and cerebrovascular disease and cancer [1,2,3,4,5]
We selected adults between 20 and 59 years of age who were enrolled in the NHANES III survey, a stratified multistage clustered probability survey conducted in a noninstitutionalized US population, and had data from at least one cognitive test available (n = 5,144)
Kaplan-Meier analyses stratified by the 2 test groups demonstrated a trend toward higher mortality among male participants with 1 standard deviation (SD) increases in their symbol digit substitution test (SDST) and serial digit learning task (SDLT)
Summary
A state that involves problems with memory, learning, thinking, language, complex attention, and executive function, has been associated with cardiovascular and cerebrovascular disease and cancer [1,2,3,4,5]. Subjects generally have higher rates of comorbidities or subclinical illnesses, which may confound the risk of death compared to younger and healthier subjects. These studies that have focused on elderly subjects are not generalizable to a broader population of younger subjects. Differences exist in measurements (e.g., using either global cognitive function tests or different aspects of cognitive domain tests) in evaluating the association with mortality. Little work has been done on which predominant cognitive domain is associated with mortality.
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