Dynamic Changes in Cognitive Activity and Global Cognition in the Memory and

Aging Project

Members (in alphabetical order): Amber, David, Doug, Emily, Frances,

Joey, Kim, Gerald, Rich

Presenter: Frances

Purpose

• To identify whether cognitive activity is a leading or lagging indicator for global cognition.

• Hypothesis: Cognitive activity will be a leading indicator for global cognition; higher cognitive activity will predict reduced global cognitive decline over time.

∆ ∆∆

∆∆∆

Current cognitive Activity

Cognitive Performance

CA1

CA2

CA3

CA4

CP1

CP2

CP3

CP4

int

int

slope

slope

11

1

time1

time2

time3

time4

time1

time2

time3

time4

Bivariate Dual Change Score Model

Methods

• Sample

– 990 participants who had baseline global cognition score, at least five cognitive activities completed, and no dementia.

Measures• The following were rescaled from 0-100 to be

on the same scale: – Global cognitive score

• Based on 19 tests from the following domains: episodic memory, semantic memory, working memory, perceptual speed, and visuospatial ability

– Cognitive activities• Based on playing games, writing letters, reading books,

magazine, and newspaper• Age: Centered at 75 years old at baseline and standardized

as a continuous variable

Statistical Analysis

• Bivariate Dual Change Score Models

• Mplus v.5.2

• Stata v.10

Results

Description of Global Cognition and Cognitive Activities over 7 Waves

020

4060

80C

ogni

tive

Act

ivity

1 2 3 4 5 6 7Visit

Predicted individual growth curve Mean growth curve

-50

050

100

Glo

bal C

ogni

tion

1 2 3 4 5 6 7Visit

Predicted individual growth curve Mean growth curve

Individual and Mean Trajectories for Cognitive Activity and Global Cognition

Global Cognition Dual Change Score Model

Cognitive Activities Dual Change Score Model

Bivariate Dual Change Score Model for Global Cognition and Cognitive Activities

*All models exclude the proportional change parameter for cognitive activities.

No effect of activity on cognitionNo effect of cognition on activity

∆y

∆∆

∆∆∆x

Current cognitive Activity

Cognitive Performance

CA1

CA2

CA3

CA4

CP1

CP2

CP3

CP4

1

1

time1

time2

time3

time4

time1

time2

time3

time4

Bivariate Dual Change Score (Full Dynamics) Model

57.1*

60.9*

-5.25*

-3.35 n.s

216.5*

246.6*

0.2390.239

0.239

-1.84 n.s -1.84 n.s-1.84 n.s

0 0 0

0.039 n.s 0.039 n.s0.039 n.s

age0.03 n.s

0.03 n.s

-5.9*

14.1

3.7* -0.05 n.s

-0.41

-.07

0.42

#slope and intercept factor inter-correlations are standardized estimates

0.43

0.03

0.35

50

52

54

56

58

60

0 1 2 3 4 5 6 Visit

Global Cognition Cognitive Activity

Change in Mean Global Cognition and Cognitive Activity Over Visit

Summary

• The decline in cognitive activities & global cognition is correlated over time but the change trajectories do not appear to influence each other.

• Cognitive activities are neither leading nor lagging indicators for cognitive decline over time.

• Relationship is likely due to a third variable that is unmeasured in our model

Next Steps

• We are currently writing up the manuscript for submission to JINS

• We are working on individual cognitive domains as the outcomes of the bivariate dual change score models.