Research suggests that cigarette smoking speeds the progression from relapsing- remitting MS to secondary progressive MS, greatly reducing the quality of patients’ lives.
From the day the Surgeon General’s report on the hazards of cigarette smoking was released in 1964, the public has been aware of its negative health effects, but few know that for patients with multiple sclerosis (MS) smoking may have a direct impact on the progression of their disease.
In a recent study conducted in the Department of Neurology at the Guilan University of Medical Sciences in Rasht, Iran, researchers found that patients suffering from relapsing-remitting multiple sclerosis (RRMS) who also smoked more than ten cigarettes per day had a greater risk than non-smokers of progressing to secondary progressive MS, or SPMS.
While relapsing-remitting MS is characterized by periods of disease activity followed by periods of remission, those with secondary progressive MS no longer experience remission, but rather their disease remains on a “low simmer” and, as the damage to their brain and spinal cord progresses, they experience ever greater disability.
Another study on the effects of smoking on MS progression conducted by researchers at the Harvard School of Public Health in 2005 suggested that “the risk of developing secondary progressive multiple sclerosis was more than three times higher in smokers than in non-smokers who had a relapsing–remitting clinical onset of multiple sclerosis.” However, smoking may be part of an overall unhealthy lifestyle, which can contribute to the worsening of disease. “Information on other habits was not available and thus we could not adjust for them,” said Dr. Miguel A. Hernán of the Harvard School of Public Health in an interview with ishonest. “This is certainly a limitation of the study.”
Cause and Effect
While the findings suggest a correlation between cigarette smoking and disease progression in MS, it’s unclear just what mechanism is at work. MS is a chronic, inflammatory autoimmune disease in which the immune system attacks the protective myelin sheath covering nerve cells in the brain and spinal cord.
In order to launch an attack on this myelin sheath, T-cells from the immune system must first traverse the blood-brain barrier (BBB) which, according to Johns Hopkins University, is “a dynamic interface that separates the brain from the circulatory system and protects the central nervous system from potentially harmful chemicals.”
In a study on the effects of cigarette smoking on the BBB, researchers at the Cleveland Clinic Learner College of Medicine found that “compounds contained in TS [tobacco smoke] may affect the viability of cells comprising the BBB and trigger an inflammatory response that, in turn, may further lead to loss of BBB integrity.”
While studies have yet to be conducted on the effects of a BBB compromised by cigarette smoking on the escalation of disease progression in MS patients who smoke, these conclusions suggest that further research needs to be done.
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