According to a new investigation, people who never drink alcohol are at a significantly higher risk of developing multiple sclerosis (MS), especially if the individual also is a current or former smoker.
Findings from a recent study published in Nature better determines the effects of alcohol intake, and interaction of alcohol intake and smoking on the subsequent development of Multiple Sclerosis (MS). Subjects included 2059 cases and 2887 controls with the median duration from symptom onset to receiving a diagnosis being 1.0 year The results indicated that alcohol exposure was related to a 20 percent decrease in the risk of developing MS compared to never drinking.
Overall, smokers who were also non-drinkers had a sevenfold increased risk of developing MS when compared to those who had never smoked who reported drinking. The interaction between non-drinking and smoking as it predicted risk of developing MS risk was more significant for current smokers compared to previous smokers. There was a cumulative effect of smoking on the interaction that was found between non-drinking and smoking, with the interaction having greater predictive power with increases doses of smoking.
The findings of this study suggest that not drinking alcohol may significantly increase the risk of developing MS, particularly for those who have smoked in the past or present. As a characteristic of MS is an overactive immune system, the effects of alcohol which decrease the immune system may explain the association.
The association between never drinking and the development MS was stronger for smokers which also makes sense as smoking has harmful effects on the immune system, making it harder for the body to fight off disease.
Results From Previous Studies
Results from a few small studies and meta-analyses demonstrate inconsistent results. In a Danish cohort study, results indicated that adolescents who consumed alcohol had a decreased risk of developing MS later in life in both genders. These findings were not dose specific for women, with the protective effects found for those who drank a small, moderate or large amount of alcohol, when compared with those who didn’t drink at all.
For men, the findings were dose specific. Men who drank a small amount of alcohol had a lower risk of developing MS compared to men who didn’t drink at all. However, there were no such effects found for men who drank a moderate or large amount.
In a prospective study conducted with two large cohorts of women, results indicated that neither total amount of alcohol consumed nor type of alcohol consumed (beer, wine or liquor) related to an increased risk of developing MS.
In the first meta-analysis, there was no evidence found showing that alcohol exposure related to an increased risk of developing MS. There was an indication of a possible protective factor of alcohol exposure on rates of MS but the authors cautioned that this conclusion needed to be validated with additional research. In a larger meta-analysis, results indicated that alcohol consumption had a positive effect on MS development in some studies and with negative outcomes found in others.
In an investigation conducted in Sweden involving two case-control studies, results indicated a dose-dependent inverse relationship between alcohol consumption and the risk of developing MS. This association was statistically significant in both genders. In one study, women who consumed large amounts of alcohol had an odds ratio of .6 for developing MS compared to non-drinking women, indicating decreased risk compared to women who never drank. Similarly, men who reported consuming a lot of alcohol had an odds ratio of .5 also indicating decreased risk.
In the other study, the odds ratio for both men and women who drank was .7 compared to non-drinkers. A side finding of this investigation was that in both studies, the negative effects of smoking was more significant among non-drinkers, indicating an interaction between these two behavioral variables.
The researchers who conducted the recent study caution using these findings to dictate treatment recommendations although they are useful for clinical practice and understanding risk factors for individuals who have a genetic predisposition to develop MS. While they said the results do suggest there is no need to tell patients with MS heritability or who already have MS to abstain from drinking alcohol completely, they also don’t support telling such patients to increase their alcohol consumption.
“Consumption of alcohol has detrimental effects on other disease conditions, and better understanding of the mechanisms behind our findings may help to define ways to achieve protection against MS by other means than alcohol consumption,” the researchers stated.