Psychological stress does not appear to play a part in the development of amyotrophic lateral sclerosis (ALS), with patients showing similar levels of prior stressful events, occupational stress, and anxiety as a control group, as well as higher resilience, a study shows.
The study, “Is psychological stress a predisposing factor for amyotrophic lateral sclerosis (ALS)? An online international case-control study of premorbid life events, occupational stress, resilience and anxiety,” appeared in the journal PLOS ONE.
Stress has been proposed as a risk factor for developing Alzheimer’s disease and other forms of dementia. Stressful events that impair the body’s immune system may also be associated with the onset of multiple sclerosis, while studies in rodents showed that chronic restraint stress causes a similar cell loss to that observed in Parkinson’s. However, evidence supporting the role of psychological stress as a trigger for common neurological disorders is still lacking.
One study found that high stress, a type A personality — characterized by impatience, hostility, and higher competitiveness — and physical activity (as a trigger for oxidative stress) were more frequent in people with ALS, but this research did not explore gender differences and did not use standard measurements of stress or personality.
In the current study, a research team from the University of Sydney in Australia assessed whether ALS patients may have been subjected to more potential stressors than peoplewithout ALS in a control group, which included patients’ partners, relatives, and friends, among others, and whether their levels of resilience and anxiety could affect the response to stress.
For this purpose, the scientists asked 400 ALS patients (with a mean age of 61.5, including 149 women) and 450 people without ALS used as controls (with a mean age of 57.3, including 320 women) to fill out an online questionnaire on significant life events, using items from a modified Social Readjustment Rating Scale and from self-described significant events. These were then combined to create a Life Events Inventory, with scores calculated for events occurring in age ranges from 0-20 years and 21-40 years, as well as for two, five, and 10 years before ALS diagnosis.
Sporadic ALS was observed in 91% of patients, with 9% having familial disease. Most patients (58%) had the “classic” upper and lower motor neuron ALS variant. Median disease duration was one year.
Only 85 individuals (10%) reported one or more self-described significant events, with an average of 2.5 events in 11 male controls, 1.9 in 24 male ALS patients, 2.8 in 34 female controls, and 2.4 in 16 female patients.
Women showed higher Life Events Inventory scores than men for all ages and subgroups. Men with ALS, who had a mean age 62, and male controls, who had a mean age of 61.8, did not differ in their scores for all ages combined, for the 0-20 and 21-40 age ranges, or for the previous two, five and 10 years.
In contrast, women with ALS, who had a mean age of 60.7, had lower scores than female controls, who had a mean age of 55.5, in the preceding five- and 10-year periods.
Men reported higher occupational stress than women, but no differences were found between patients and controls. Anxiety scores also did not differ.
“Our results do not therefore support the hypothesis that psychological stress is a risk factor for developing ALS,” the scientists wrote.
They added that higher resilience in ALS could be due to personality differences, as found in previous research, and that future studies should explore genetic variants involved in ALS and resilience as a way of studying possible disease processes.