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.
