Cognitive reserve in secondary progressive multiple sclerosis

Background: Consistent with the cognitive reserve hypothesis, lifetime intellectual enrichment protects MS patients from cognitive impairment. As studies have focused predominately on patients with relapsing–remitting courses, it is unknown whether lifetime enrichment is protective against cognitive impairment in patients with secondary-progressive MS (SPMS), a more advanced disease course. Objective: Examine whether greater lifetime intellectual enrichment moderates/reduces the deleterious effect of SPMS on memory and cognitive efficiency. Methods: Twenty-five SPMS patients and 25 healthy controls (HC) completed neuropsychological tasks, yielding two composite scores: memory and cognitive efficiency. An estimate of lifetime enrichment was created from educational attainment and vocabulary knowledge. Regression analyses predicted memory and cognitive efficiency, with age, sex, intellectual enrichment and group (SPMS, HC) controlled in step one, and the interaction between intellectual enrichment and group evaluated within step two. Results: Interactions emerged between intellectual enrichment and group when predicting memory ( R 2 Δ=0.081, p = 0.041) and cognitive efficiency ( R 2 Δ=0.064, p = 0.024), such that SPMS patients exhibited deficits relative to HCs at lower levels of enrichment, but these SPMS-related cognitive deficits were absent at higher levels of enrichment. Conclusion: Intellectual enrichment protects SPMS patients from cognitive impairment, thereby extending the cognitive reserve hypothesis to this more advanced MS disease course.