HEALTH NEWS

Study Title:

Smoking and Brain Damage

Study Abstract

Background: Cigarette smoking has been linked to higher susceptibility and increased risk of progressive multiple sclerosis (MS). The effects of smoking on MRI characteristics of patients with MS have not been evaluated.

Objectives: To compare the MRI characteristics in cigarette smoker and nonsmoker patients with MS.

Methods: We studied 368 consecutive patients with MS (age 44.0 ±SD 10.2 years, disease duration 12.1 ± 9.1 years) comprising 240 never-smokers and 128 (34.8%) ever-smokers (currently active and former smokers). The average number of packs per day smoked (±SD) was 0.95 ± 0.65, and the mean duration of smoking was 18.0 ± 9.5 years. All patients obtained full clinical and quantitative MRI evaluation. MRI measures included T1, T2, and gadolinium contrast-enhancing (CE) lesion volumes (LVs) and measures of central, global, and tissue-specific brain atrophy. The associations between smoking status and MRI measurements were assessed in regression analysis.

Results: Smoking was associated with increased Expanded Disability Status Scale (EDSS) scores (p = 0.004). The median EDSS scores (interquartile range) in the ever-smoker group and the active-smoker group were both 3.0 (2.0), compared with 2.5 (2.5) in never-smokers. There were adverse associations between smoking and the lesion measures including increased number of CE lesions (p < 0.001), T2 LV (p = 0.009), and T1 LV (p = 0.003). Smoking was associated with decreased brain parenchymal fraction (p = 0.047) and with increases in the lateral ventricle volume (p = 0.001) and third ventricle width (p = 0.023).

Conclusions: Smoking is associated with increased blood–brain barrier disruption, higher lesion volumes, and greater atrophy in multiple sclerosis.


Abbreviations: BPF = brain parenchymal fraction; CE = contrast-enhancing; CIS = clinically isolated syndromes; EDSS = Expanded Disability Status Scale; GMF = gray matter fraction; LV = lesion volume; LVV = lateral ventricle volume; MS = multiple sclerosis; P-P = probability–probability; PPMS = primary progressive multiple sclerosis; rp = partial correlation; RRMS = relapsing–remitting multiple sclerosis; SE = standard error of slope; SPMS = secondary progressive multiple sclerosis; 3VW = third ventricle width; WMF = white matter fraction.

From press release:

Persons with multiple sclerosis who smoked for a little as six months during their lifetime had more destruction of brain tissue and more brain atrophy than MS patients who never smoked, a study by neuroimaging specialists at the University at Buffalo has shown.

Research published in the Aug. 18, 2009, issue of Neurology®, the medical journal of the American Academy of Neurology, showed that "ever-smokers" had more brain lesions and greater loss of brain volume, as well as higher scores on the Expanded Disability Status Scale (EDSS), than MS patients who had no history of smoking.

The EDSS score is an average number derived from measures of various functions of the central nervous system. It is based on a scale from 0 to 10, with 10 representing greatest disability. Nonsmokers recorded an average EDSS score of 2.5, compared to 3.0 for ever-smokers.

"Cigarette smoking is one of the most compelling environmental risk factors linked to the development and worsening of MS," said Robert Zivadinov, M.D., Ph.D., UB professor of neurology, director of the Buffalo Neuroimaging Analysis Center (BNAC) where the research was conducted and first author on the study.

"The biological basis of the potential link between smoking and MS has not yet been fully elucidated," Zivadinov said. "In addition to nicotine, cigarette smoke contains hundreds of potentially toxic components, including tar, carbon monoxide and polycyclic aromatic hydrocarbons.

"In MS patients, smoking was associated with higher increased lesion burden and greater brain atrophy. Our results indicate that a wide range of quantitative brain MRI markers are affected by smoking in MS patients."

The study involved 368 consecutive patients who were seen at the Baird Multiple Sclerosis Center of the Jacobs Neurological Institute (JNI), UB's Department of Neurology, UB School of Medicine and Biomedical Sciences.

Within the study cohort, 128 had a history of smoking: 96 were active smokers who had smoked more than 10 cigarettes-per-day in the three months prior to the study start and 32 were former smokers who had smoked cumulatively for at least six months sometime in the past. The remaining 240 participants were lifelong nonsmokers.

Nearly 80 percent in both groups were female, and nearly 75 percent were diagnosed with progressive MS, characterized by a steadily increasing disability.

All participants were evaluated by a clinician, were rated by disability using the EDSS scale and underwent a variety of high-resolution magnetic resonance imaging (MRI) scans conducted by MRI analysts who were blinded to the patient's clinical status and characteristics.

Results showed that smokers with MS had a greater breakdown of the blood-brain barrier, had nearly 17 percent more brain lesions -- patches of inflammation in the sheath surrounding the nerve fibers that impair their function -- than nonsmokers with MS, and also had less brain volume. Smoking also was associated with increased physical disability, as measured by the EDSS score.

Bianca Weinstock-Guttman, M.D., director of the Baird MS Center, UB associate professor of neurology and a principal co-author on the study, said: "The findings underscore the detrimental effect of smoking, providing a link between smoking and a more severe brain injury in MS patients.

"Increased antismoking education in schools and more targeted smoking cessation programs for patients with MS should be encouraged further and supported."

Study Information

. Zivadinov, B. Weinstock-Guttman, K. Hashmi, N. Abdelrahman, M. Stosic, M. Dwyer, S. Hussein, J. Durfee, and M. Ramanathan
Smoking is associated with increased lesion volumes and brain atrophy in multiple sclerosis
Neurology
2009 August
University of Buffalo