Association Between Time Spent Outdoors and Risk of Multiple Sclerosis, 2022, Sebastian et al.

[SNT Gatchaman]

Association Between Time Spent Outdoors and Risk of Multiple Sclerosis
Prince Sebastian; Nicolas Cherbuin; Lisa F. Barcellos; Shelly Roalstad; Charles Casper; Janace Hart; Gregory S. Aaen; Lauren Krupp; Leslie Benson; Mark Gorman; Meghan Candee; Tanuja Chitnis; Manu Goyal; Benjamin Greenberg; Soe Mar; Moses Rodriguez; Jennifer Rubin; Teri Schreiner; Amy Waldman; Bianca Weinstock-Guttman; Jennifer Graves; Emmanuelle Waubant; Robyn Lucas; on behalf of US Network of Pediatric Multiple Sclerosis Centers

Background and Objectives
This study aims to determine the contributions of sun exposure and ultraviolet radiation (UVR) exposure to risk of pediatric-onset multiple sclerosis (MS).

Methods
Children with MS and controls recruited from multiple centers in the United States were matched on sex and age. Multivariable conditional logistic regression was used to investigate the association of time spent outdoors daily in summer, use of sun protection, and ambient summer UVR dose in the year before birth and the year before diagnosis with MS risk, with adjustment for sex, age, race, birth season, child's skin color, mother's education, tobacco smoke exposure, being overweight, and Epstein-Barr virus infection.

Results
Three hundred thirty-two children with MS (median disease duration 7.3 months) and 534 controls were included after matching on sex and age. In a fully adjusted model, compared to spending <30 minutes outdoors daily during the most recent summer, greater time spent outdoors was associated with a marked reduction in the odds of developing MS, with evidence of dose-response (30 minutes–1 hour: adjusted odds ratio [AOR] 0.48, 95% confidence interval [CI] 0.23–0.99, p = 0.05; 1–2 hours: AOR 0.19, 95% CI 0.09–0.40, p < 0.001). Higher summer ambient UVR dose was also protective for MS (AOR 0.76 per 1 kJ/m2, 95% CI 0.62–0.94, p = 0.01).

Discussion
If this is a causal association, spending more time in the sun during summer may be strongly protective against developing pediatric MS, as well as residing in a sunnier location.

Link | PDF (Neurology)

 

[SNT Gatchaman]

MS etiology is understood to be a combination of genetic predisposition, infectious exposures, and other environmental and behavioral risk factors. In particular, low sun exposure, low ultraviolet radiation (UVR) exposure, and low vitamin D status have been well characterized as environmental risk factors for adult-onset MS, with a particular increase in risk associated with insufficient sun exposure in childhood. However, to date, research on sun/UVR exposure in MS has been limited to mostly adult populations.

In this study, we analyze data from a multicenter case-control study that investigated environmental risk factors for pediatric MS. Our objective was to examine the associations of sun exposure (measured as time spent outdoors) and UVR exposure (measured as ambient UVR dose) with risk of pediatric MS. Based on the known associations of these factors with risk of adult-onset MS, our hypothesis was that low sun exposure and low UVR exposure would be associated with greater risk in this pediatric population.

Greater time spent outdoors during the present/most recent summer on weekends was associated with significantly lower odds of MS, with evidence of a dose-dependent response.

In this fully adjusted model, compared to spending <30 minutes outdoors daily during summer, spending 30 minutes to 1 hour was associated with a 52% reduction in MS odds (AOR 0.48, 95% CI 0.23–0.99, p = 0.05), and spending 1 to 2 hours was associated with a 81% reduction (AOR 0.19, 95% CI 0.09–0.40, p < 0.001).

Use of sun protection was not associated with the odds of having MS; however, greater ambient UVR dose was associated with significantly lower odds of MS (AOR 0.76 per 1 kJ/m2, 95% CI 0.62–0.94, p = 0.01).

 

[SNT Gatchaman]

 

[SNT Gatchaman]

(I wonder if vitamin D levels is a proxy and that UV radiation exposure is not the key factor, but instead near-infrared.)

 

[Amw66]

(I wonder if vitamin D levels is a proxy and that UV radiation exposure is not the key factor, but instead near-infrared.)

There was a graph I saw in a paper years ago which plotted ms incidence rates v location . There was a definite relationship - the farther from the equator the higher the incidence , suggesting sunlight exposure plays a part. It's always assumed as being vit D related , but infrared radiation is interesting.

 

[SNT Gatchaman]

Yes the latitude relationship is well established. An interesting feature is that early life exposure appears to be key, ie if you moved to a lower latitude after 12yo you carried your higher risk, or vice versa.

See The latitude gradient for multiple sclerosis prevalence is established in the early life course (2021, Brain) from some of my local colleagues.

Here, for the first time, we present epidemiological evidence that strongly suggests that the environmental drivers of the latitudinal gradient act at the earliest points in a person’s life, perhaps even in utero or in the neonatal period. These data are of importance to those who are considering studies aimed at reducing multiple sclerosis risk by modification of environmental factors, which clearly need to be introduced at much earlier time points than have previously been considered.

 

[Mij]

Vitamin D did not reduce multiple sclerosis disease activity after a clinically isolated syndrome, 2023, Helmut Butzkueven et al

Abstract
Low serum levels of 25-hydroxyvitamin D (25(OH)D), and low sunlight exposure, are known risk factors for the development of multiple sclerosis. Add-on vitamin D supplementation trials in established multiple sclerosis have been inconclusive. The effects of vitamin D supplementation to prevent multiple sclerosis is unknown.

We aimed to test the hypothesis that oral vitamin D3 supplementation in high-risk clinically isolated syndrome (abnormal MRI, at least three T2 brain and/or spinal cord lesions), delays time to conversion to definite multiple sclerosis, that the therapeutic effect is dose-dependent, and that all doses are safe and well tolerated.

We conducted a double-blind trial in Australia and New Zealand. Eligible participants were randomised 1:1:1:1 to placebo, 1000, 5000, or 10 000 IU of oral vitamin D3 daily within each study centre (n=23) and followed for up to 48 weeks. Between 2013 and 2021, we enrolled 204 participants. Brain MRI scans were performed at baseline, 24 and 48 weeks.

The main study outcome was conversion to clinically definite multiple sclerosis based on the 2010 McDonald criteria defined as either a clinical relapse or new brain MRI T2 lesion development.

We included 199 cases in the intention-to-treat analysis based on assigned dose. Of these, 116 converted to multiple sclerosis by 48 weeks (58%). Compared to placebo, the HRs (95%CI) for conversion were 1000 IU 0.87 (0.50, 1.50); 5000 IU 1.37 (0.82, 2.29); and 10 000 IU 1.28 (0.76, 2.14). In an adjusted model including age, sex, latitude, study centre, and baseline symptom number, clinically isolated syndrome onset site, presence of infratentorial lesions, and use of steroids, the HRs (versus placebo) were 1000 IU 0.80 (0.45, 1.44); 5000 IU 1.36 (0.78, 2.38); 10 000 IU 1.07 (0.62, 1.85). Vitamin D3 supplementation was safe and well tolerated.

We did not demonstrate reduction in multiple sclerosis disease activity by vitamin D3 supplementation after a high-risk clinically isolated syndrome.

https://academic.oup.com/brain/advance-article/doi/10.1093/brain/awad409/7469896?login=false

 

[Mij]

Canada continues to have the highest rates of MS in the world.

• Over 90,000 Canadians living with MS – 1 in every 400
• 4,377 people are diagnosed with MS each year - almost 12 people per day
• Average age of diagnosis is 43 years
• 75% of the people living with MS are women
• 90% of people with MS are initially diagnosed with relapsing-remitting forms of MS, while 10% are diagnosed with progressive forms of MS.

https://mscanada.ca/ms-research/latest-research/prevalence-and-incidence-of-ms-in-canada-and-around-the-world#:~:text=Canada continues to have one,MS – 1 in every 400