Diabetes, Hypertension, Smoking Linked with Brain Shrinkage in MS Patients

Diabetes, hypertension, and active smoking correlate with more brain shrinkage in multiple sclerosis (MS) patients, a new study shows.

The study, “Assessing the burden of vascular risk factors on brain atrophy in multiple sclerosis: A case- control MRI study” was published in the journal Multiple Sclerosis and Related Disorders.

MS is a chronic inflammatory disease characterized by the loss of myelin — the fat-rich substance that wraps around nerve fibers (axons) — leading to the progressive destruction of nerve cells. While triggered by a malfunctioning immune system, other conditions might influence MS progression. In fact, diabetes and hypertension have detrimental effects on MS patients.

In this study researchers evaluated how three common vascular risk factors — diabetes mellitus type 1 or type 2, hypertension, and active smoking — correlate with brain injury severity, measured as a reduction in brain volume (also called atrophy or shrinkage) by magnetic resonance imaging (MRI) in MS patients.

Diabetes might be responsible for accelerated rates of brain volume loss; alterations in blood glucose levels are linked with a pro-inflammatory and oxidative stress (an imbalance between the body’s production of potentially harmful reactive oxygen species and its ability to contain them) in the brain.

Hypertension is known to cause damage to small blood vessels and alterations in the brain that may potentially accelerate MS disease progression. In turn, cigarette smoking may promote neurodegeneration through its effects on the vascular system.

The study included 326 patients with MS, of whom 116 (35.6 percent) had at least one vascular risk factor, and 27 (8.3 percent) of whom had at least two risk factors. A group of 210 MS patients without any vascular risk served as control.

In total, 49 patients had diabetes (15 percent), 44 patients had hypertension (13.4 percent), and 50 patients were active smokers (15.3 percent).

All patients underwent MRI and different parameters were evaluated, including the volumes of the whole brain, white matter, gray matter, and cortical gray matter.

The brain’s gray matter harbors the cell bodies of nerve cells, as well as the axon terminals, the tips of nerve fibers that nerve cells use to communicate. As MS progresses, nerve cell bodies are damaged, which may underlie the shrinking (atrophy) of gray matter.

White matter is composed of nerves coated in myelin, the prime target of the immune system’s attack in MS.

The analysis showed a reduction in brain volume among MS patients with vascular risk factors, with the burden of volume loss increasing in those with multiple risk factors.

Specifically, MS patients with diabetes and hypertension exhibited reduced volumes of whole brain, but also of gray matter and cortical gray matter, compared to the participants used as controls. Smokers showed a reduced cortical grey matter in comparison with the MS control group.

Overall, these results suggest that vascular risk factors, such as diabetes, hypertension, and smoking, might exacerbate brain volume loss and overall disease progression in patients with MS.

The team emphasized that “vascular comorbidities and risk factors should always be considered and carefully treated in patients with MS, with a focus on limiting brain damage and disease evolution.”