Staying out in the sun all day, every day is questionably risky to your health. However, a new study published in Neurology suggests a correlation between daily sun exposure and the delayed onset of multiple sclerosis (MS) symptoms. Additionally, weight seems to play a role in the delayed onset on the disease’s initial symptoms.
For the study, researchers from Denmark’s Copenhagen University Hospital enrolled 1,161 Danish participants diagnosed with MS in a study. Of the nearly 1,200 participants, 836 were female and 325 were male. Participants completed questionnaires regarding their sun exposure habits—whether or not they spent time in the sun daily, their vitamin D supplement usage, and the amount of fatty fish consumed at 20-years-old and during their teenage years. Additionally, researchers took blood samples from each of the participants for genotyping, a method of determining genetic differences in DNA.
Analyzing the data and factoring out genetic risks based on their genotyping, researchers found two associations to be investigated further. According to the results, 88% of participants who received daily sun exposure throughout their adolescence developed the first symptoms of MS at an average age of 32.9 years, compared to 31 years of age for those who did not receive daily sun exposure. In terms of weight, participants who were overweight (18% of those involved in the study) at 20-years-old experienced MS onset on average 1.6 years prior to those who were considered to be of average weight. Those who were considered underweight at age 20 saw the onset of their first MS symptoms an average of 3.1 years later than those who were overweight.
While experts deny the study to be proof of a cause-effect relationship between low vitamin D and the onset of MS, the results do offer more evidence linking MS to a lack of sun exposure and its increased frequency among populations of colder climates. The link with obesity may also be explained by a vitamin D deficiency, as those with higher body fat content generally show lower blood levels of the sunshine vitamin. Additionally, the study further proves the criticality of adolescence and the development of MS symptoms.
Potential limitations of the study include the following:
- Recall bias based on researchers relying on participants’ ability to accurately recall daily sun exposure in their earlier years
- Potential difficulties or inconsistencies in memory as a symptom of MS affecting participants’ ability to recall past habits
- Limited participant selection in terms of race, ethnicity, and geographic location
MS is a chronic, complex, and unpredictable disease that affects each and every patient differently, from symptoms to severity, progression, and mortality. Symptoms can range from mild to severe and tend to hit in waves through periods of attacks, exacerbations, relapses, and remissions.
Furthermore, MS is an immune disorder that causes the body to attack myelin, the fatty tissue that surrounds and protects nerve fibers. The disease causes scar tissue to form, resulting in miscommunication between the brain and other body parts by disrupting and distorting nerve impulses traveling from the brain through the spinal cord.
The disease appears to affect more women than men and is more prevalent among cold climate populations. MS patients are usually diagnosed between 20 and 50 years-old and tend to live an average of seven years less than those without MS, usually due to complications or linked medical conditions. While MS is not a life-threatening disease in all cases, its affects on the body can impair and greatly alter a patient’s quality of life and day-to-day tasks.
Symptoms may include any of the following:
- Pain and painful sensations
- Slurred speech
- Impaired vision (blurred or double vision)
- Muscle weakness or tightness
- Impaired or poor balance and coordination
- Paralysis (temporary to permanent)
- Digestive system concerns (bladder or bowel dysfunction)
- Sexual dysfunction
- Forgetfulness, impaired concentration
- Changes in mood, depression
Globally, MS affects an estimated 2.3 million people.
Sources for Today’s Article:
Scutti, S., “First Symptoms Of MS Slightly Delayed By Sunlight And Lower BMI,” Medical Daily web site, October 7, 2015; http://www.medicaldaily.com/first-symptoms-ms-slightly-delayed-sunlight-and-lower-bmi-356216.
“MS may start later for those who spend teenage summers in the sun,” EurekAlert web site, October 7, 2015; http://www.eurekalert.org/pub_releases/2015-10/aaon-mms100115.php.
Norton, A., “Sun Exposure in Teen Years May Delay Onset of MS: Study,” HealthDay News, Philly.com web site, October 7, 2015; http://www.philly.com/philly/health/topics/HealthDay704007_20151007_Sun_Exposure_in_Teen_Years_May_Delay_Onset_of_MS__Study.html.
“What is Multiple Sclerosis?” National Multiple Sclerosis Society web site; http://www.nationalmssociety.org/NationalMSSociety/media/MSNationalFiles/Brochures/Brochure-What-Is-MS.pdf, last accessed October 8, 2015.