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Predictors of Cognitive Functioning in Midlife

Predictors of Cognitive Functioning in Midlife. S. L. Willis, K. W. Schaie, S. H. Hofer, & L. Hoffman The Pennsylvania State University, University Park, Pennsylvania/USA. Aims of the Study:. To describe cohort differences in cognitive trajectories in midlife (Age Range: 43 - 63 )

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Predictors of Cognitive Functioning in Midlife

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  1. Predictors of Cognitive Functioning in Midlife S. L. Willis, K. W. Schaie, S. H. Hofer, & L. Hoffman The Pennsylvania State University, University Park, Pennsylvania/USA

  2. Aims of the Study: • To describe cohort differences in cognitive trajectories in midlife (Age Range: 43 - 63) • Inductive Reasoning • Word Fluency • Psychomotor Speed • To identify predictors of intercept and slope of cognitive trajectories • Time invariant: Education, Gender, Apo-E Allele 4 • Time varying: BMI (Body Mass Index)

  3. Sample • N = 888 males - females • Mean Age: • Mean Educational Level: • 5 Birth Cohorts studied at same midlife age range • Cohort 1910 (birth cohorts 1907 - 1913) • Cohort 1917 (birth cohorts 1914 - 1920) • Cohort 1924 (birth cohorts 1921 - 1927) • Cohort 1931 (birth cohorts 1928 - 1934) • Cohort 1938 (birth cohorts 1935 - 1941)

  4. Cognitive Outcomes • Inductive Reasoning - Ability to identify a pattern in a series of letters and to utilize the pattern in selecting the next letter in the series • Word Fluency - Number of words generated in 5 minutes • Psychomotor Speed - Speed in shifting cognitive sets in performing written task

  5. Analysis Plan (1) • Latent Growth Curve Models: • Linear • Quadratic • Unconditional Growth Models examining: Effects of age, cohort and retest • Age: Exact age at each of 3 occasions, centered at age 53 • Cohort represented by dummy codes, centered at 1963 cohort • Cohort differences examined for intercept & linear/quadratic slopes of age • Retest represented by dummy code; enter study at age 46 or age 53

  6. Analysis Plan (2) • Predictor Models • Time varying predictors were parameterized to express separate effects of between person and within person variation on level and change (slope) • Continuous predictors (BMI) • Between person - mean across 3 occasions • Within person - Deviation from person’s mean at each occasion

  7. Results for Reasoning: Cohort Differences in Score Level • Level of score at age 53: Overall positive cohort trend • No difference in score level at age 53 for the two earliest cohorts (1910, 1917) • More recent cohorts (1924, 1931, 1938) scored significantly higher at age 53, compared to the 1917 cohort • Limited Retest effects • Retest effects larger for 1910 cohort than for 1917 cohort

  8. Results for Reasoning:Cohort Differences in Trajectories(Piecewise models)

  9. Results for Reasoning:Predictors • Gender: Positive effect for women • Education: Positive effect on score level • Apo-E: No effect • BMI: No effect

  10. Results for Fluency: Cohort Differences in Score Level • Level of score at age 53: • No difference in score level at age 53 for the three earliest cohorts (1910, 1917, 1921) • Most recent cohort (1938) scored significantly higher at age 53, compared to the earlier cohorts • Limited Retest effects • Retest effects larger for 1910 and 1924 cohorts than for 1917 cohort

  11. Results for Fluency:Cohort Differences in Trajectories(Piecewise models)

  12. Results for Fluency:Predictors • Gender: Positive effect for women • Education: Positive effect on score level • Apo-E: No effect • BMI: Higher BMI in midlife related to lower Fluency score

  13. Results for Psychomotor Speed: Cohort Differences in Score Level • Level of score at age 53: Overall positive cohort trend: • Cohort 1910 score lower at age 53 than 1917 cohort • No difference between Cohorts 1917 and 1924 at age 53 • Most recent cohorts (1931,1938) scored significantly higher at age 53, compared to the earlier cohorts • Limited Retest effects • Retest effects larger for 1910 and 1924 cohorts than for 1917 cohort

  14. Results for Psychomotor Speed:Cohort Differences in Trajectories(Piecewise models)

  15. Results for Psychomotor Speed:Predictors • Gender: Positive effect for women • Education: Positive effect on score level • Apo-E: No effect • BMI: Higher BMI in midlife related to poorer Psychomotor Speed score

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