Manual Workers Have a Doubled Risk of ALS

A new study by the University of Malta reveals that individuals engaged in heavy physical labour have an increased risk of developing amyotrophic lateral sclerosis (ALS), supporting a link between a history of intense physical activity and this neurological condition.

ALS is a progressive neurological disease that attacks the nerves that interact with the body’s muscles. The disease typically leads to complete paralysis of the body, robbing patients of their ability to walk, speak, eat and breathe. In Malta, about 11 patients are diagnosed with ALS every year. Some patients die months after the onset of symptoms while others survive for years.

The research team studied Maltese patients with ALS and healthy elderly volunteers who took part in an ongoing study aiming at identifying genetic and environmental factors associated with ALS in Malta. Recently, the team discovered that Maltese ALS patients have a unique genetic makeup compared to their European counterparts.

In this study, based on demographic data collected over a four-year period, the researchers found that manual workers were twice as likely to develop ALS. Indeed, close to two thirds of ALS patients reported a blue-collar job as their main occupation during their entire career.

“We have long known that Italian football players, American National Football League players and military serviceman have an increased risk of ALS compared to the general population. A common thread running through these professions is sustained or strenuous physical exertion. Our study supports this notion,” said the study’s lead researcher Dr Ruben J. Cauchi, a senior lecturer at the University’s Faculty of Medicine & Surgery and lead investigator at the University’s Centre for Molecular Medicine and Biobanking.

Despite the fact that Malta does not have professional football players nor an elite military service, the study found that sweat-inducing jobs including those in construction and carpentry were associated with a higher ALS risk. Patients in these occupations were more prone to develop bulbar-onset ALS, a form of the disease in which speech or swallowing problems appear before muscle weakness in the limbs. Patients with bulbar-onset ALS fare worse than those with limb-onset.

The setting up of a national ALS Registry and Biobank at the University of Malta in 2017, with the aim of identifying and tracking ALS patients and healthy volunteers, was key for this discovery. Right now, the research team is studying the interplay between genetics and environmental exposures in causing ALS in patients. 

Reference: Wismayer MF, Borg R, Wismayer AF, et al. Occupation and amyotrophic lateral sclerosis risk: a case-control study in the isolated island population of Malta. Amyotroph. Lateral. Scler. Frontotemporal Degener. 2021;0(0):1-7. doi: 10.1080/21678421.2021.1905847

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