Better sleep linked to improved verbal memory in multiple sclerosis

Key takeaways:

• Researchers analyzed more than 500 persons with MS on measures of sleep and cognition.
• Sleep disturbance is a likely intervention for individuals with MS and memory deficits.

WEST PALM BEACH, Fla. — In two separate cohorts of individuals with multiple sclerosis and memory issues, better sleep was linked to improved verbal memory, according to a poster at ACTRIMS 2024.

“A lot of patients with [multiple sclerosis] have memory difficulties and although there has been research looking at how to improve memory like cognitive rehabilitation and remediation, none of those have met the threshold for empirical evidence,” Sarah Levy, PhD, assistant professor in the department of neurology at Icahn School of Medicine at Mount Sinai, told Healio.

Levy and colleagues attempted to ascertain the relationship between patient-reported sleep disturbance and memory dysfunction within two separate cohorts of individuals with multiple sclerosis.

Their study was split into a research cohort and a clinic cohort.

The research cohort included 160 individuals with relapsing-remitting MS who had been diagnosed at least 5 years prior to inclusion (mean age 34.4±7.7 years; 66% female). Patients had their cognition evaluated at baseline and during a 3-year follow-up. Testing included the Verbal and Nonverbal Memory Composite tests, as well as the Simple Cognitive and Complex Cognitive Speed Composite tests for non-memory analysis. Percent change was converted to numeral scores and averaged into composite change scores.

In the clinic cohort, 335 individuals with MS (relapsing-remitting, n = 259; progressive, n = 76; mean age 45±11.1 years; 72% female) were evaluated by Mount Sinai’s cognitive screening service, also at baseline and during a 3-year follow-up. Testing was performed on verbal, nonverbal memory (Hopkins Verbal Learning Test Revised, CANTAB Paired Associate Learning [PAL]) and comparison task via the Symbol Digit Modalities Test (SDMT).

Sleep disturbance for both cohorts was measured via the Insomnia Severity Index questionnaire, and divided into categories of improved, stable or worsened sleep.

According to results, in the research cohort, 22 individuals reported improved sleep, 123 reported stable sleep and 15 replied that sleep worsened. In the clinic cohort, 64 logged improved sleep, 240 were stable and 31 reported their sleep worsened.

In the research cohort, Levy and colleagues found a medium-sized link between sleep changes and verbal memory (F[2,159] = 3.23), and that those with improved sleep demonstrated improved verbal memory relative to stable or worsened sleep, though sleep chance was unreliably related to other cognitive outcomes. In the clinic cohort, similar relationships existed between sleep change and verbal memory, improved sleep and improved verbal memory, but unrelated to both SDMT and PAL.

“When patient-reported sleep improved, there was this strong correlation with an improvement in their verbal memory,” Levy told Healio. “This is a statistically strong relationship.”