1. Patient Cognitive Reserve and MS-Related Cognitive Dysfunction
Chair
Timothy L. Vollmer, MD
Faculty
John DeLuca, PhD

2. Study Rationale and Objective
Introduction
Cognitive impairment affects approximately 2/3 of patients with MS
MS-related cognitive dysfunction is only partially predicted by MRI estimates of brain pathology
Study objective
To determine whether higher premorbid intellectual functioning, ie, cognitive reserve (efficiency and capacity of neural networks), protects patients from MS-related cognitive dysfunction
Cognitive reserve is best measured on the basis of estimated verbal intelligence as determined on the Wide Range Achievement Test–Third Edition
Lower cognitive reserve: Z = -1; higher cognitive reserve: Z = +1
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

3. Components of Cognitive Function Measurement Tools
Simple processing efficiency
Symbol Digit Modalities Test (SDMT) – Oral Version
Complex information processing efficiency
Paced Auditory Serial Addition Test (PASAT)
Verbal learning and memory
Logical Memory subtests (LM-I and LM-II) of the Wechsler Memory Scale–Revised
Verbal learning: LM-I
Verbal memory: LM-II
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

4. Simple Processing Efficiency
Total Cognitive Reserve
Group Lower Higher
Z score Z score (Percentile) Z score (Percentile)
Healthy controls * (72nd) * (68th)
MS patients † (12th) † (40th)
P value <.001
* The correlation between cognitive reserve and simple processing efficiency did not reach significance in healthy controls (r = -.01, P >.50).
† The correlation between cognitive reserve and simple processing efficiency did not reach significance in MS patients (r = 21, P >.10).
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

5. Complex Information Processing Efficiency
Total Cognitive Reserve
Group Lower Higher
Z score Z score (Percentile) Z score (Percentile)
Healthy controls * (52nd) * (61st)
MS patients † (6th) † (58th)
P Value
The correlation between cognitive reserve and complex information processing efficiency
(PASAT) did not reach significance in healthy controls (r = .15, P >.10).
† There was a large significant correlation between cognitive reserve and complex
information processing efficiency (PASAT) in MS patients (r = .42, P = .001).
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

6. Verbal Learning Total Cognitive Reserve
Group Lower Higher
Z score Z score (Percentile) Z score (Percentile)
Healthy controls * (59th) * (73rd)
MS patients † (11th) † (78th)
P value <.001
* The correlation between cognitive reserve and verbal learning did not reach significance in
healthy controls (r = .14, P >.10).
† There was a large significant correlation between cognitive reserve and verbal learning in MS patients (r = .61, P <.001).
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

7. Verbal Memory Z score Z score (Percentile) Z score (Percentile)
Total Cognitive Reserve
Group Lower Higher
Z score Z score (Percentile) Z score (Percentile)
Healthy controls * (54th) * (74th)
MS patients † (11th) † (74th)
P value <.001
* The correlation between cognitive reserve and verbal memory did not reach
significance in healthy controls (r = .22, P >.10).
† There was a large significant correlation between cognitive reserve and verbal
memory in MS patients (r = .53, P <.001).
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31:

8. Conclusions
The detrimental effect of MS on aspects of cognitive functioning is modified by patient cognitive reserve
Higher cognitive reserve protects patients from MS-related complex information processing inefficiency and verbal learning and verbal memory deficits
The protective effect of higher cognitive reserve allows patients to maintain cognitive performance comparable to that of healthy controls
However, higher cognitive reserve had no significant effect on MS-related deficits in simple processing efficiency
These findings may help to explain the weak association between MRI markers of MS brain pathology and cognition noted in previous studies
Sumowski JF, et al. J Clin Exp Neuropsychol. 2009;31: