Thursday, 7 November 2013

Month of Birth Effect is not seen in South America

Fragoso YD et al. Multiple sclerosis in South America: month of birth in different latitudes does not seem to interfere with the prevalence or progression of the disease. Arq Neuropsiquiatr. 2013 Sep;71(9A):573-9. doi: 10.1590/0004-282X20130098

Objective To assess whether the month of birth in different latitudes of South America might influence the presence or severity of multiple sclerosis(MS) later in life. 

Methods Neurologists in four South American countries working at MS units collected data on their patients' month of birth, gender, age, and disease progression. 
Results Analysis of data from 1207 MS patients and 1207 control subjects did not show any significant variation in the month of birth regarding the prevalence of MS in four latitude bands (0-10; 11-20; 21-30; and 31-40 degrees). There was no relationship between the month of birth and the severity of disease in each latitude band.
Conclusion The results from this study show that MS patients born to mothers who were pregnant at different Southern latitudes do not follow the seasonal pattern observed at high Northern latitudes.

To the Month of Birth Effect that has been reported in Some North Hemisphere countries and even Australia. Has not been found in South American countries. Obviously one has to figure elevation into the equation, but  this report supports the lack of month of birth effect reported earlier in Brazil. 

The relevance has also been questioned (see below) is this one in the eye for the Vitamin D hypothesis.



23 Apr 2013

ViĆ° Streym S, Rejnmark L, Mosekilde L, Vestergaard P.No effect of season of birth on risk of type 1 diabetes, cancer, schizophrenia and ischemic heart disease, while some variations may be seen for pneumonia and multiple sclerosis. Dermatoendocrinol. 2013 Apr 1;5(2):309-16. doi: 10.4161/derm.22779

BACKGROUND: The risk of type 1 diabetes (T1DM), infections, cancer, schizophrenia and multiple sclerosis (MS) has been associated with environmental factors including vitamin D status.
MATERIALS AND METHODS: Data were obtained from all children born in Denmark in 1940 (n = 72,839), 1977 (n = 89,570), and 1996 (n = 74,015). Information on contacts to hospitals (1977-2009) was obtained from the National Hospital Discharge Register. The main exposure variable was season of birth as a proxy variable for vitamin D status (summer: April-September and winter: October-March).
RESULTS:No associations between season of birth and risk of MS were seen in the 1940 cohort or the 1996 cohort. In the 1977 cohort, there was a borderline statistically significant decreased risk of MS in those born during wintertime compared with those born during summertime (HR = 0.70, 95% CI: 0.47-1.04, p = 0.07). There were no significant differences within the groups regarding season and risk of T1DM at any age, T1DM before 10 y, infection, any type of cancer, schizophrenia and myocardial infarction. In the 1977 cohort the risk of pneumonia was significantly lower among those born in the summer compared with the winter at any age (HR 0.91, 95% CI 0.85-0.97, p < 0.01) and at age < 10 y (HR 0.90, 95% CI 0.84-0.97, p < 0.01).
CONCLUSION: MS and pneumonia in young subjects may be related to season of birth and thus maternal vitamin D exposure. Low sunlight exposure in the winter time leading to low vitamin D levels during pregnancy may be a potential explanation.
 So dents in the hypothesis of ProfG from Denmark also.
Wonder what he thinks about it?

2 comments:

  1. I wonder if there is perhaps insufficient focus on vitamin A as well as D. Perhaps there is some reason to suspect an interaction of these vitamins in early childhood and also their combined immunomodulatory effects. I have recently added 10,000 international units of vitamin a to my regimen of beta interferon, minocycline, vitamin d, melatonin, inosine, vitamin b and within hours I noticed a difference. I had also added 2 weeks prior to this saffron supplements which are sort of vitamin a like, it seems. Perhaps this is another avenue worth exploring?

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  2. Looks like every Brazilian neurologist is on the author list:-) Do native Americans in Brazil, Argentina, U.S. and Australian aborigines have increased incidence of MS due to latitude or are euro genes required?

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