Occupational complexity and cognitive resilience in the Framingham Heart Study

Abstract

Background: Greater occupational complexity may be protective against dementia in later life, but it is unclear if it contributes to cognitive resilience and whether different aspects of occupational complexity are associated with resilience. We examined relationships between occupational complexity related to data, people, and things, and cognitive resilience to neurodegeneration. Method: 1,699 participants from the Framingham Heart Study Offspring cohort who were aged ≥60 years, had a plasma total tau (t‐tau) measure (a marker of neurodegeneration), and a neuropsychological (NP) exam visit within five years of the plasma t‐tau measurement were included. Plasma t‐tau was measured using the Simoa assay (Quanterix) on samples collected at Exam 8 (2005‐2008). NP factor scores were previously derived for memory, language, and executive function using confirmatory factor analysis. Occupational data were collected at the NP exam, from which occupational complexity was disaggregated into data complexity, people complexity, and things complexity according to the 1970 US Census Dictionary of Occupational Titles. Cognitive resilience was operationalized using a residual approach by regressing each NP factor score on the plasma t‐tau measure, adjusting for age, sex, education, time from blood draw, and APOE ε4 status. The adjusted residuals were then regressed on each type of occupational complexity, dichotomized into higher complexity versus lower complexity. Result: The sample was, on average, 70 years of age, 53% female, and had 15 years of education. Higher data (β = 0.20, 95% confidence interval (CI) = 0.15‐0.25, p<0.001), people (β = 0.11, 95% CI = 0.07‐0.15, p<0.001), and things (β = 0.05, 95% CI = 0.01‐0.09, p = 0.015) occupational complexity were most strongly associated with resilience in executive function. Higher data (β = 0.10, 95% CI = 0.05‐0.15, p<0.001) and people (β = 0.07, 95% CI = 0.03‐0.11, p = 0.001) occupational complexity were associated with resilience in memory. Higher data (β = 0.07, 95% CI = 0.01‐0.12, p = 0.014) occupational complexity was associated with resilience in language. Conclusion: Specific types of occupational complexity contribute to resilience to neurodegeneration in specific cognitive domains differently. Occupational complexity may offer the most resilience in executive function and occupations with high data complexity may offer the most cognitive resilience.