Obesity accelerates disability and cognitive decline in multiple sclerosis patients

New findings from a Swedish data analysis reveal that individuals with obesity who are diagnosed with multiple sclerosis (MS) experience faster disability progression, more pronounced cognitive decline, and a lower quality of life over a 15-year period compared to MS patients with normal weight. While the link between obesity and the risk of developing MS has been established, this research sheds new light on how obesity affects the course of the disease post-diagnosis.

Lars Alfredsson, PhD, a professor at the Karolinska Institutet in Sweden, presented these findings at the recent European Committee for Treatment and Research in Multiple Sclerosis (ECTRIMS) and the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) meeting held in Milan from October 11 to 13, both in-person and online.

The study, conducted between 2005 and 2019, investigated the impact of obesity on disease progression, cognitive function, and quality of life among MS patients in Sweden. As part of the research, participants completed comprehensive lifestyle and environmental questionnaires when they entered the study, and a follow-up questionnaire in 2021 aimed to assess any changes in their conditions.

The study included 3,249 MS patients, with an average age of 37.8, of which 74% were women. Over a 15-year follow-up period, these individuals were closely monitored for changes in disability, quality of life, and cognition.

Obesity status was determined using body mass index (BMI), a widely accepted measure of body fat based on height and weight. A BMI within the range of 18.5 to 24.99 was considered normal, 25 to 30 indicated overweight, and above 30 signified obesity. Disability progression was assessed using the Expanded Disability Status Scale (EDSS), with scores ranging from 0 to 10, reflecting increasing levels of disability.

Compared to MS patients with a normal weight, those with obesity experienced a .022-point annual increase in EDSS scores, indicating faster disability progression. Though the difference may seem modest, it was statistically significant, according to Alfredsson.

Obesity was linked to a 41% higher risk of reaching an EDSS score of 3, which typically signifies a transition from minimal to moderate disability, and a 31% higher risk of reaching an EDSS score of 4, which denotes significant disability without walking impairments. The analysis accounted for factors such as age, sex, disease type, duration, treatments, and smoking.

Interestingly, the study found that being overweight did not elevate the risk of these negative outcomes, said Alfredsson.

Obese individuals were also more likely to experience declines in their quality of life, with a 40% higher risk of physical deterioration and a 24% higher risk of psychological decline, as defined by at least a 7.5-point increase on the Multiple Sclerosis Impact Scale 29 (MSIS29).

Among those who maintained a consistent BMI throughout the follow-up period, the disparities in disability and quality of life were even more pronounced than in the overall study population. For instance, patients who remained obese throughout the study were at a 50% higher risk of reaching an EDSS score of 3, a 70% higher risk of physical deterioration, and a 36% higher risk of psychological decline compared to those who consistently maintained a normal weight.

For patients with obesity whose BMI remained stable, the risk of cognitive decline, defined as at least an 8-point increase on the Symbol Digit Modalities Test (SDMT), was 47% higher compared to those who maintained a normal weight.

In conclusion, the research suggests that obesity has a detrimental impact on both the progression of MS, health-related quality of life, and cognitive function in individuals with the condition. The study’s strengths include a large number of patients with follow-up data in the Swedish MS register, though it should be noted that BMI data were self-reported and not objectively measured, which is a limitation of the study.