People with multiple sclerosis are 48 percent more likely to have high blood pressure compared to the general population — and to people with other demyelinating diseases, a new study reports. Its researchers also emphasize that hypertension is already linked to poorer outcomes in MS patients.
The study, “Cardiovascular conditions in persons with multiple sclerosis, neuromyelitis optica and transverse myelitis,” was published in the journal Multiple Sclerosis and Related Disorders.
Like all demyelinating diseases, MS is marked by damage to the protective cover – called myelin – that surrounds nerve fibers in the brain, optic nerves, and spinal cord.
Two other diseases, neuromyelitis optica spectrum disorder (NMOSD), and transverse myelitis (TM), are also demyelinating disorders of the central nervous system. But the three have widely different clinical characteristics, and comorbidities — while common in MS patients — have not been studied extensively in NMOSD and TM.
Researchers with Case Western Reserve University in Cleveland, Ohio, investigated the prevalence of cardiovascular conditions like hypertension in a group of MS, NMOSD, and TM patients in the U.S. Cardiovascular conditions, even those that develop in people with other diseases (as a comorbidity), are generally considered modifiable through diet and exercise. But few large-scale studies have looked into their prevalence or burden in people with demyelinating diseases.
Those that have suggest that cardiovascular conditions are either as prevalent or more prevalent in people with MS and NMOSD than healthy people.
Using a case-control study (people enrolled in the Accelerated Cure Project and treated at special clinics), the research team compared the burden of several cardiovascular-associated diseases — type 2 diabetes, heart disease, hyperlipidemia (high levels of fat in blood, or high cholesterol), and hypertension (high blood pressure) — in 1,548 MS patients, 306 NMOSD patients, and 145 people with TM, and then compared findings with those of 677 controls without a demyelinating disease.
Researchers adjusted cardiovascular risk by controlling the data for such known risk factors as demographics, smoking history, obesity, family history, and presence of other cardiovascular conditions.
Results found that MS patients were 48 percent more likely to have hypertension compared to controls — but no differences were seen among NMOSD or TM patients and the control group.
“In MS cases, we observed an elevated burden of hypertension compared to the controls,” the researchers wrote, noting a number of earlier studies also “demonstrated adverse associations between cardiovascular conditions and MS outcomes.”
They speculated that the hypertension was more common in MS patients because “it is known that hypertension can disrupt the blood-brain barrier (BBB), and in MS the BBB is compromised, which may facilitate infiltration of autoreactive immune cells into the central nervous system.”
Interestingly, the prevalence of other cardiovascular conditions — including high cholesterol, diabetes, and heart disease — did not differ across patient groups and controls. Likewise, no differences were found in age of cardiovascular disease onset among patients and controls.
“In summary, this study demonstrates the burden of cardiovascular conditions are similar, in persons with demyelinating diseases as they are in unaffected individuals, with the exception of hypertension being more common in those with MS even after accounting of established cardiovascular risk factors,” the researchers wrote.
Because of the link between cardiovascular ills and MS disease severity, they also recommend further studies to better “characterize the causal mechanisms underlying the associations between cardiovascular conditions and adverse MS outcomes; and to examine if similar associations exist in NMOSD and TM.”