Astonishing
C is a medical Wikipedia and occasionally mentions an oddity that blows my mind.This morning, she told me about the relationship between latitude and the incidence of multiple sclerosis. Wait, what?
That's right. The further you live from the equator, the more likely you are to develop multiple sclerosis.
This was originally discovered in 1923, and a meta-analysis published in 2019 confirmed the risk:
This new meta-analysis confirms that MS prevalence is still strongly positively associated with increasing latitude and that the gradient is increasing, suggesting that potentially modifiable environmental factors, such as sun exposure, are still strongly associated with MS risk.
This new meta-analysis confirms that MS prevalence is still strongly positively associated with increasing latitude and that the gradient is increasing, suggesting that potentially modifiable environmental factors, such as sun exposure, are still strongly associated with MS risk.
I don't know if anyone has ever focused on the cloudiest cities (Grand Rapids is one of the cloudiest cities in the country) to see if the incidence of MS is higher compared to other cities in the U.S., but it seems reasonable to try.
No one has proven what causes this relationship. The strongest theory involves Vitamin D levels. Here's a study offering a possible explanation:
Seasonal affective disorder (SAD), another illness for which latitude is a risk factor, appears to be related to the decrease in ambient light during the winter months, and offers some relevant insights into the geographical distribution of risk for developing MS. Researchers have found a relationship between degree of reported seasonal difficulties in a population sample and altered immunological function. Furthermore, the effects of bright light on mood have been shown to be regulated through the eye. We hypothesize that the risk of developing MS is related to impairment of the immune system caused by light deprivation prior to adulthood.
Seasonal affective disorder (SAD), another illness for which latitude is a risk factor, appears to be related to the decrease in ambient light during the winter months, and offers some relevant insights into the geographical distribution of risk for developing MS. Researchers have found a relationship between degree of reported seasonal difficulties in a population sample and altered immunological function. Furthermore, the effects of bright light on mood have been shown to be regulated through the eye. We hypothesize that the risk of developing MS is related to impairment of the immune system caused by light deprivation prior to adulthood.
There's your bizarre but true medical fact for the day.
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