In the study, conducted by Robert Zivadinov, M.D., Ph.D., UB professor of neurology, director of the Buffalo Neuroimaging Analysis Centre (BNAC), the results were based on Magnetic Resonance Images (MRIs) of the participants.
The researchers at the University at Buffalo examined 368 MS patients ranged in age from 35-55 years, and had been living with MS for an average of 13 years, of which some were smokers and some were non-smokers.
"Cigarette smoke has many properties that are toxic to the central nervous system, and cigarette smoking has been linked to higher susceptibility and risk of progressive multiple sclerosis," Zivadinov said.
"Interactions between cigarette smoking and genetic and immunologic factors may point to mechanisms in disease pathogenesis. No previous studies have investigated differences in MRI characteristics between MS cigarette smokers and MS non-smokers," he said.
In the study, patients from the three most common forms of MS were included.
253 patients had relapsing-remitting MS, acute attacks with full or partial recovery; 9 had primary-progressive MS, steady worsening from onset; and 90 had secondary-progressive MS, characterized by occasional attacks and unremitting progression.
Another 16 participants had experienced MS for the first time.
In the study group, 128 had smoking history, of which 96 were active smokers who prior to the study start had smoked more than 10 cigarettes-per-day in the three months.
32 were former smokers who had sometime in the past smoked cumulatively for at least 6 months. The remaining 240 participants were not exposed to active smoking.
The average smoking duration was 17.6 years, and 17 was the average number of cigarettes smoked per day.
No significant differences were there between smokers and non-smokers on the basis of age, disease duration, disease course and total lifetime use of disease-modifying drugs.
The analysis made after comparing MRIs from smokers and non-smokers showed that the smokers had significantly higher disability scores and lower brain volume than the non-smokers.
Also a significant relationship between a higher number of packs-per-day smoked and lower volume of the neocortex, the portion of the cerebral cortex that serves as the center of higher mental functions for humans, was found.
"Smoking appears to influence the severity of MS and to accelerate brain atrophy and the disruption of the blood-brain barrier in MS patients," said Zivadinov.
"MS patients should be counselled to stop smoking, or at least to cut down so they can preserve as much brain function as possible,"he said.