INDIVIDUAL DIFFERENCES IN MEMORY FUNCTION Richard N. Jones, John N. Morris, Adrienne Rosenberg, Paul...

INDIVIDUAL DIFFERENCES IN MEMORY FUNCTION

Richard N. Jones, John N. Morris, Adrienne Rosenberg, Paul Malloy

HRCA Research and Training Institute, Boston

Ken Kleinman

Harvard Medical School, Boston MAJason Allaire

Wayne State University, Institute of Gerontology, Detroit MIMichael Marsiske

University of Florida, Institute on Aging, Gainesville

ACTIVE Advanced Cognitive Training for Vital and Independent Elderly

funded as a cooperative agreement with the National Institute on Aging and the

National Institute of Nursing Research.

Participating Institutions & Principal Investigators:Hebrew Rehabilitation Center for Aged John Morris, Ph.D.Indiana University David Smith, M.D.Johns Hopkins University George Rebok, Ph.D.Pennsylvania State University Sherry Willis, Ph.D.University of Alabama at Birmingham Karolin Ball, Ph.D.Wayne State University Michael Marsiske, Ph.D.

Coordinating CenterNew England Research Institutes Sharon Tennstedt, Ph.D.

Objectives

• Characterize performance on memory task in cognitively normal older adults

• Use Latent Growth Curve Modeling (LGM) techniques

• Separately model initial recall and learning

• Explore association of background variables and recall, learning

Rey AVLTAuditory Verbal Learning Test

(Lezak, 1983; Rey, 1964)

• 15 unrelated word list, read at 2 sec. intervals

• Participants asked to recall words

• List re-read four times

• Repeated recall trials

• Intrusion list

• Delayed Recall and Recognition task

Latent Growth Modeling

• Psychometric approach to repeated measures data

• Individual differences in intercept and slope over time captured in latent variables (initial recall, learning)

• Certain parameterizations equivalent to random coefficient models, mixed models, hierarchical linear models

Methods: Participants•HRCA

–elder housing•IU

–community centers•UAB

–drivers licenses, ID cards–eye clinic attendees

•WSU–community organizations –urban residential settings

•JHU

–in and around urban geriatric center

–urban senior high-rise housing

–suburban retirement community

–urban & rural medical centers

•PSU –PACE enrollees

Eligibility and Exclusion Criteria

• Eligibility Criteria– age 65– living in non-institutional setting– available for duration of trial

• Exclusion Criteria– vision impairment– hearing loss– impaired communication– reported disability– Alzheimer’s dx or MMSE<23– cancer dx w/ limited life expectancy– current chemo/radiation– CVA in previous 12 months– in other cognitive training– high level depressive sx (CESD>16)

Background Variables

• Demographics– Age– Sex– Ethnicity– Education

• Cognitive Functioning– General (MMSE) – Reasoning ability

(STAMAT)– Vocabulary (Kit)– Digit symbol

substitution (WAIS)

Table 1. Subject characteristics, ACTIVE pilot (n=169). mean (±s.d.) or valid frequency Characteristic n percent Total 169 100 Men 29 17 Women 140 83 Age group 65-74 years 96 58 75-84 59 35 85 and older 12 7 Ethnicity White, non-Hispanic 67 40 Black or African-American 94 56 Other 8 5 Level of education less than 12 years/GED 54 32 12 years/GED 54 32 more than 12/GED 61 36 SF-36 Physical 149 43 (±10) SF-36 Mental 149 54 (±8) Cognitive functioning Reasoning (Word Series) 167 7 (±5) Digit symbol (DSST) 169 35 (±15) Vocabulary (words) 169 6 (±3) MMSE 169 27 (±2)

w

ord

s r

ec

alle

d

A V L T tria l

0

3

6

9

1 2

1 5

1 2 3 4 5

LGM Parameterization without Background Variables

yi = + i + i

i = + i

0

0000

=

1 0

1 1 1 2 1 3 1 4

VAR() = =

* 0 0 0 0

0 * 0 0 0 0 0 * 0 0 0 0 0 * 0 0 0 0 0 *

*

* VAR() = =

*

* *

Alternative Functional Forms of AVLT Growth

Linear

=

1 0

1 1 1 2 1 3 1 4

Logarithmic (ln(t+1))

=

1 0.000

1 0.693 1 1.099 1 1.386 1 1.609

Quadratic

=

1 0 0

1 1 1 1 2 4 1 3 6 1 4 16

Logarithmic Growth FunctionEstimated final time score

=

1 0.000

1 0.693 1 1.099 1 1.386 1 *

42 = 1.494 (0.033)

1.609-1.4940.033 = 3.48

Transformed metric

=

1 0.000/1.494

1 0.693/1.494 1 1.099/1.494 1 1.386/1.494 1 *

or

=

1 0.000

1 0.464 1 0.736 1 0.928 1 *

Table 2. Fitted AVLT performance growth model, ACTIVE Pilot (n=169).

parameter estimate (se)1

time scores

12 0.00 2

22 0.46

32 0.74

42 0.93

52 1.00 (0.02)

Growth factor means

1 (initial recall) 5.53 (0.13)

2 (learning) 5.21 (0.18)

Growth factor variance/covariance

11 (initial recall) 2.58 (0.34)

22 (learning) 4.43 (0.61)

21 (covariance of growth factors) 0.00

Observed variable (AVLT) residual variance

11 0.33 (0.18)

22 1.33 (0.17)

33 0.86 (0.13)

44 0.93 (0.17)

55 1.99 (0.27)

Model chi-square (df), P 9.73 (10), P=0.47 CFI 1.00 RMSEA 0.03 1 - standard error 2 - entries in italic typeface are not estimated, but fixed equal to the shown value.

0

2

4

6

8

10

12

14

16

0 1 2 3 4 5 6

Model implied trajectories

LGM Parameterization with Background Variables

yi = + i + i

i = + x + i

0

0000

=

1 0.000

1 0.464 1 0.736 1 0.928 1 *

VAR() = =

* 0 0 0 0

0 * 0 0 0 0 0 * 0 0 0 0 0 * 0 0 0 0 0 *

*

*

* * * * * * * * *

* * * * * * * * * VAR() = =

*

0 *

Table 3. Association of participant characteristics and AVLT growth model factors. ACTIVE Pilot (n=169).

initial recall learning

standard- standard- ized ized characteristic est (se)1 effect est (se) 1 effect

Women 0.77 (0.34) 0.50* 0.67 (0.40) 0.35

Age group 75-84 -0.09 (0.29) -0.06 -0.42 (0.34) -0.21 85 and older -0.98 (0.55) -0.63 -0.86 (0.66) -0.44

Black or African-American -1.12 (0.30) -0.73*** 0.84 (0.35) 0.42*

less than 12 years/GED2 0.01 (0.31) 0.01 0.33 (0.37) 0.16

Mental/Physical Health SF-36 Physical† 0.01 (0.01) 0.06 0.01 (0.02) 0.04 SF-36 Mental† 0.01 (0.02) 0.04 -0.02 (0.02) -0.08

Reasoning (Word Series) † 0.00 (0.04) -0.01 0.09 (0.05) 0.20

Digit Symbol† 0.01 (0.01) 0.08 0.03 (0.01) 0.21*

Vocabulary (words) † 0.06 (0.05) 0.14 0.07 (0.06) 0.12

General cognition (MMSE) † -0.05 (0.07) -0.07 0.32 (0.08) 0.34*** Model chi-square (df), P 57.14 (43), P=0.07 CFI 0.989 RMSEA 0.044 * P<0.05, ** P<0.01, *** P<0.001 † - effect size estimates shown standardized to respect to mean an variance of dependent and background variable; all other (dichotomous) covariates standardized with respect to dependent variable only. 1 - estimate (est) and standard error (se) 2 - general equivalency degree




Women 0.77 (0.34) 0.50* 0.67 (0.40) 0.35

* P<0.05, ** P<0.01, *** P<0.001 † - effect size estimates shown standardized to respect to mean an variance of dependent and background variable; all other (dichotomous) covariates standardized with respect to dependent variable only. 1 - estimate (est) and standard error (se) 2 - general equivalency degree




Age group 75-84 -0.09 (0.29) -0.06 -0.42 (0.34) -0.21 85 and older -0.98 (0.55) -0.63 -0.86 (0.66) -0.44





Black or African-American -1.12 (0.30) -0.73*** 0.84 (0.35) 0.42*


0

3

6

9

12

15

0 1 2 3 4 5 6

trial

AV

LT

re

ca

ll (w

ord

s)

Black/African-American, Not Hispanic

White and other ethnicity groups




less than 12 years/GED2 0.01 (0.31) 0.01 0.33 (0.37) 0.16 * P<0.05, ** P<0.01, *** P<0.001 † - effect size estimates shown standardized to respect to mean an variance of dependent and background variable; all other (dichotomous) covariates standardized with respect to dependent variable only. 1 - estimate (est) and standard error (se) 2 - general equivalency degree




Mental/Physical Health SF-36 Physical† 0.01 (0.01) 0.06 0.01 (0.02) 0.04 SF-36 Mental† 0.01 (0.02) 0.04 -0.02 (0.02) -0.08





Reasoning (Word Series) † 0.00 (0.04) -0.01 0.09 (0.05) 0.20





Digit Symbol† 0.01 (0.01) 0.08 0.03 (0.01) 0.21*





Vocabulary (words) † 0.06 (0.05) 0.14 0.07 (0.06) 0.12





General cognition (MMSE) † -0.05 (0.07) -0.07 0.32 (0.08) 0.34*** * P<0.05, ** P<0.01, *** P<0.001 † - effect size estimates shown standardized to respect to mean an variance of dependent and background variable; all other (dichotomous) covariates standardized with respect to dependent variable only. 1 - estimate (est) and standard error (se) 2 - general equivalency degree

Conclusion

• LGM provides a comprehensible model of initial recall and learning performance on the AVLT task

• Alternative summary measures are suggested by considering effect of background variables on initial recall and rate learning

LGM Alternative Parameterization without Background Variables

yi = + i + i

i = + i

1=*

2=1

2=

1

2=1

2=

1

=

1 0

1 1 1 2 1 3 1 4

VAR() = =

* 0 0 0 0

0 * 0 0 0 0 0 * 0 0 0 0 0 * 0 0 0 0 0 *

0

* VAR() = =

*

* *

Word List Used in ACTIVE

• Drum• Curtain• Bell• Coffee• School• Parent• Moon

• Garden• Hat• Farmer• Nose• Turkey• Color• House• River

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