LYON, FRANCE—Cognitive reserve may provide protection from disease-related cognitive decline independently of brain reserve in patients with multiple sclerosis (MS), according to a study presented at the 28th Congress of the European Committee for Treatment and Research in MS (ECTRIMS). Greater maximal lifetime brain size (ie, brain reserve) was associated with a slower rate of cognitive decline than lower maximal lifetime brain size among patients with MS. Brain reserve is established by genetics rather than through voluntary control.
Intellectual enrichment (a source of cognitive reserve) gained in early life may reduce the harmful effect of T2 lesion load on cognitive status, even after controlling for brain reserve, according to James F. Sumowski, PhD, Research Scientist at the Kessler Foundation Research Center in West Orange, New Jersey. That is, life experiences (ie, cognitive reserve) protect against cognitive decline among MS patients independently of genetic sources of reserve (brain reserve).
Estimating Patients' Brain Reserve and Cognitive Reserve
Dr. Sumowski and his colleagues studied 62 patients with MS to test the brain reserve and cognitive reserve hypotheses and to investigate whether cognitive reserve protects against cognitive decline independently of brain reserve. The researchers used total T2 lesion load to estimate the extent of patients' MS neuropathology. Intracranial volume was the basis for the group's estimates of patients' maximal lifetime brain size.
Participants completed a questionnaire surveying the cognitive leisure activities that they had pursued in their early 20s, and the questionnaires helped the investigators gauge patients' cognitive reserve. Patients rated leisure activities based on the frequency with which they had pursued them. Tests such as the Symbol Digit Modalities Test were used to assess participants' cognitive status.
Of the 62 patients, 41 had relapsing-remitting MS and 21 had secondary progressive MS. Patients had received an average of 13 years of education and had an average Expanded Disability Status Scale score of 3.2.
“Greater brain reserve, estimated with intracranial volume, moderated or reduced the deleterious impact of T2 lesion load on cognitive status,” said Dr. Sumowski. The study provides “the first evidence for brain reserve in MS,” he added. Greater cognitive reserve independently moderated the harmful effects of T2 lesion load as well. “Randomized, controlled trials of cognitive leisure are needed to support a causal relationship between leisure and protection from cognitive decline,” Dr. Sumowski concluded.