Can Mediterranean diet help people with MS preserve thinking skills?

People with multiple sclerosis (MS) who follow a Mediterranean diet may have a lower risk for problems with memory and thinking skills than those who do not follow the diet, according to a preliminary study released today, March 1, 2023, that will be presented at the American Academy of Neurology's 75th Annual Meeting being held in person in Boston and live online from April 22-27, 2023.

The Mediterranean diet includes a high intake of vegetables, legumes, fruits, fish and healthy fats such as olive oil, and a low intake of dairy products, meats and saturated fatty acids.

"It's exciting to see that we may be able to help people living with MS maintain better cognition by eating a Mediterranean diet," said study author Ilana Katz Sand, MD, of the Icahn School of Medicine at Mount Sinai in New York, New York, and a member of the American Academy of Neurology. "Cognitive difficulties are very common in MS, and they often get worse over time, even with treatment with disease-modifying therapies. People living with MS are very interested in ways they can be proactive from a lifestyle perspective to help improve their outcomes."

The study involved 563 people with MS. People completed a questionnaire to show how closely they followed the Mediterranean diet. They were assigned a score of zero to 14 based on their responses with higher scores given to those who more closely followed the diet.

Researchers then divided participants into four groups based on their diet scores, with the lowest group having scores of zero to four and the highest group having scores of nine or higher.

Participants also took three tests assessing their thinking and memory skills. Cognitive impairment was defined as scoring less than the fifth percentile on two or three of the tests.

A total of 108 people, or 19%, had cognitive impairment.

The researchers found that people who more closely followed the Mediterranean diet had a 20% lower risk for cognitive impairment than people who did not follow the diet.

Among those in the lowest diet score group, 43 of 133 people, or 34%, had cognitive impairment compared to 13 of 103 people, or 13%, of people in the highest diet score group.

The relationship was stronger among people with progressive MS, where the disease steadily worsens, than among those with relapsing-remitting MS, where the disease flares up and then goes into periods of remission.

Importantly, Katz Sand noted, the results were the same when researchers rigorously adjusted for other factors that could affect the risk of cognitive impairment, such as socioeconomic status, smoking, body mass index, high blood pressure and exercise.

"Among health-related factors, the level of dietary alignment with the Mediterranean pattern was by far the strongest predictor of people's cognitive scores and whether they met the study criteria for cognitive impairment," Katz Sand said.

She noted that longer studies that follow people over time and well-designed interventional clinical trials are needed to confirm the results. A limitation of the study was that tests were taken only once.