Vitamin D and long-term memory in multiple sclerosis

Memory disturbance is a frequent cognitive complaint by patients with multiple sclerosis (MS). Recent dementia research suggests a beneficial role for vitamin D in long-term memory functioning. While data suggest ameliorative effects of vitamin D for the physical impairments of MS, it is unknown whether vitamin D can benefit the cognitive sequelae. We examined the relationship between serum levels of vitamin D and performance on verbal and nonverbal tests of long-term memory in patients with MS.

A sample of 35 adults with relapsing-remitting MS completed cognitive testing and a vitamin D serum (25[OH]D) assay. Memory assessment used clinically established neuropsychological tests with multiple testing formats to determine whether vitamin D level was associated with memory during conditions of varying retrieval demands. Intellectual functioning and mood were also assessed to control for potential confounds.

Vitamin D level was positively associated with performance on immediate and delayed recall trials of the Rey Complex Figure Test, effects that held after controlling for intelligence and disease duration. Vitamin D level was not associated with mood, intelligence, or verbal memory performance on the California Verbal Learning Test, Second Edition.

Higher vitamin D level was associated with better nonverbal long-term memory performance in MS, particularly in conditions when no aid was given to help retrieval. These results supplement the literature on the neuroprotective effects of vitamin D and suggest that vitamin D is a worthwhile adjunct treatment for MS.