#MSVirtual2020 – Cardiovascular Risk Factors Linked to Brain Shrinkage

In people with multiple sclerosis (MS) under age 50, the presence of cardiovascular risk factors is associated with a greater loss of brain volume, including white and grey matter, a study showed.

The brain’s white matter mainly consists of nerve fibers and is typically affected by MS, while grey matter is primarily made of nerve cells.

The data also showed that the presence of at least two cardiovascular risk factors had effects comparable to exposure to a more stringent risk factor. Those findings highlight the need for clinicians to closely monitor and discuss cardiovascular risk factors and lifestyle changes with MS patients, the researchers said.

The study, “Cardiovascular risk factors affect brain volume in young MS patients” (abstract #PS04.05), was presented by Raffaello Bonacchi, MD, of the Institute of Experimental Neurology at the IRCCS San Raffaele Scientific Institute, in Italy, in an oral presentation at the MSVirtual2020, held online Sept. 11–13.

This was the 8th joint meeting of the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) and European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS).

Increasing evidence suggests that cardiovascular risk factors are associated with clinical and MRI changes reflecting worse disease outcomes in people with MS. In particular, a previous study found that diabetes, high blood pressure (hypertension), and active smoking were linked to a greater loss of brain volume — also called atrophy or shrinkage — in MS patients.

However, “previous studies have not set an age limit” in their analyses, Bonacchi said, noting that “older patients may be affected by cerebral small vessel disease-related damage in addition to MS.” In addition, the impact of different exposures to each cardiovascular risk factor has not been assessed.

That led the researchers at the Institute of Experimental Neurology to evaluate the impact of cardiovascular risk factors on brain atrophy and lesion volume in MS patients under the age of 50.

The study involved 124 MS patients (74 women and 50 men) with a mean age of 36, and 95 age- and sex-matched healthy individuals, used as controls. A total of 79 patients had relapsing-remitting MS, while 45 had progressive disease; their median disease duration was eight years.

All of the participants underwent a brain MRI to assess brain lesions and atrophy (including white and grey matter) and had a complete neurological examination. Exposure to several cardiovascular risk factors, graded as traditional or stringent based on a certain threshold, also was analyzed.

Traditional risk factors included having smoked five or more pack-years, hypertension, high levels of fat molecules in the blood (dyslipidemia), and diabetes or prediabetes. Among the stringent factors were having smoked at least 10 pack-years and receiving treatment for hypertension, dyslipidemia, or diabetes.

Of note, five pack-years corresponds to having smoked one pack of cigarettes every day for five years or having smoked five cigarettes a day for 20 years.

The results showed that compared with controls, a significantly higher proportion of MS patients had at least one traditional (39% vs. 20% in controls) or stringent (24% vs. 11% in controls) cardiovascular risk factor.

The MS patients also were more likely to have two or more traditional risk factors (12% vs. 4% in controls) and more than one stringent risk factor (6% vs. 3%) than healthy individuals.

These differences were mainly based on the participants’ smoking history, Bonacchi noted, with 42 (34%) MS patients having smoked five pack-years compared with 16 (17%) in the control group, and 23 (19%) patients having smoked 10 pack-years compared with eight (8%) healthy individuals.

In contrast to what was observed among healthy people, MS patients showed significant differences in several brain volume outcomes depending on their exposure to cardiovascular risk factors.

MS patients with at least two traditional cardiovascular risk factors had significantly lower total brain volume and grey and white matter volume than those without this type of exposure.

In addition, the presence of at least one stringent cardiovascular risk factor in MS patients was associated with significantly greater brain atrophy, lower grey and white matter volume, and larger brain lesions.

“The presence of cardiovascular risk factors is associated with brain atrophy, involving both the grey matter and white matter, in MS patients even under the age of 50,” Bonacchi said.

This suggested that brain atrophy in MS patients may occur independently of small vessel disease.

“Cardiovascular risk factors seem to have synergistic [cumulative] effects, determining brain atrophy even for levels of exposure that may often be overlooked by clinicians, when present in combination,” Bonacchi concluded.