Season play a role in developing MS?
Link between MS, season and vitamin D
thought leads to another……
over the information I just wrote up on Diabetes (see
last newsletter), I had to take just a few moments tolook something
recent reports on the seasonal variation in diabetes onset and exacerbation
have got me wondering. Diabetes isn't the only disease that can be linked
to changing ultraviolet exposure and vitamin D deficiency. There are many,
the best known is multiple sclerosis. The well known and bizarre conundrum
of multiple sclerosis has always been one of place. The closer people
live to the equator the less likely they are to get MS, the further away
the more likely. In the very last few years this has been explained by
varying levels of ultraviolet light exposure and resultant vitamin D levels.
The higher one's vitamin D level the less likely one is to get the disease.
Recent reports suggest that diabetes is most often diagnosed in March,
when vitamin D levels are at their annual low point. Does the same sort
of seasonal variation occur with multiple sclerosis?
answer is ‘sort of.'
Australian study from 2003 shows a protective effect of sun exposure during
childhood and adolescence against MS. The amount of sun exposure during
the winter months is the most important factor. [i]
A Finnish study which looked at vitamin D levels in MS patients yields
some intriguing findings. Comparing vitamin D levels in 40 MS patients
and 40 controls showed no difference during the winter but significant
differences during the summer months. MS patients had significantly lower
than average vitamin D levels during the summer. [ii]
This is interesting in light of a Spanish study published a few months
prior that looked at what time of year MS was most likely to be diagnosed.
Looking at the records of 32 patients it was determined that outbreaks
of MS are more common in the summer than the winter. [iii]
Of course we can argue that often with MS the symptoms appear months
before the disease is diagnosed and depending on how squeaky the wheel
is and how ponderously slow the healthcare system responds to individual
patient complaints, there may be a lag time of several months between
disease onset and diagnosis. And also of course, nothing against the Spanish,
but it is pretty much sunny in Spain year round and how much seasonal
variation do you expect to see? Of course the slight variations in vitamin
D levels seen during varying seasons in Spain may be far outweighed by
seasonal variations in temperature. It is well known that MS patients
have poor heat tolerance and that simple hot weather may trigger exacerbations
of the disease. [iv] Yet assume
this article is accurate, that MS is triggered in the summer more often,
when, according to the Finns, MS patient's have a lower than normal Vitamin
D level. It sort of makes sense. That's what I mean by, ‘sort of.'
isn't vague though is the effect that season of birth has in the long
run on someone's chances of developing MS. A 2005 study in the British
Medical Journal looked at 17,874 Canadian MS patients and 11,502 British
MS patients, all living in less sunny climates than Spain . [v]
The data showed a statistically significant advantage to being born
in November. Those born in November had a lower than average chance of
developing MS. The obvious explanation is that during their gestation
period their mothers provided ample vitamin D for development.
sort of information is behind an article in Medical Hypothesis titled,
“Why we should offer routine vitamin D supplementation in pregnancy and
childhood to prevent multiple sclerosis.” [vi]
Of course prenatal supplementation may also lower risk of diabetes
and a host of other diseases, but that's another story.
Past exposure to sun,
skin phenotype, and risk of multiple sclerosis: case-control study.
der Mei IA , Ponsonby
AL , Dwyer
T , Blizzard
L , Simmons
R , Taylor
BV , Butzkueven
H , Kilpatrick
Menzies Centre for Population Health Research, University
, TAS 7000, Australia
OBJECTIVE: To examine whether past high sun exposure is associated with
a reduced risk of multiple sclerosis. DESIGN: Population based case-control
study. SETTING: Tasmania ,
latitudes 41-3 degrees S. PARTICIPANTS: 136 cases with multiple sclerosis
and 272 controls randomly drawn from the community and matched on sex
and year of birth. MAIN OUTCOME MEASURE: Multiple sclerosis defined by
both clinical and magnetic resonance imaging criteria. RESULTS: Higher
sun exposure when aged 6-15 years (average 2-3 hours or more a day in
summer during weekends and holidays) was associated with a decreased risk
of multiple sclerosis (adjusted odds ratio 0.31, 95% confidence interval
0.16 to 0.59). Higher exposure in winter seemed more important than higher
exposure in summer. Greater actinic damage was also independently associated
with a decreased risk of multiple sclerosis (0.32, 0.11 to 0.88 for grades
4-6 disease). A dose-response relation was observed between multiple sclerosis
and decreasing sun exposure when aged 6-15 years and with actinic damage.
CONCLUSION: Higher sun exposure during childhood and early adolescence
is associated with a reduced risk of multiple sclerosis. Insufficient
ultraviolet radiation may therefore influence the development of multiple
levels in serum at the onset of multiple sclerosis.
M , Airas
L , Mononen
I , Heikkila
A , Viljanen
M , Hanninen
Medicity Research Laboratory, University
, Tykistokatu 6, FIN-20520 Turku
Past sun exposure and vitamin D supplementation have been associated with
a reduction in the risk of MS. We measured the serum concentration of
25-hydroxyvitamin D (25[OH]D) at the time of MS diagnosis in 40 MS patients
and 40 controls. We found no difference in the serum levels of 25(OH)D
between MS patients and controls when all samples or samples obtained
during winter months were compared, but MS patients had significantly
lower serum 25(OH)D concentrations in June to September than the controls.
The vitamin D stores were adequate for bone metabolism (> 37 nmol/L)
in 70% of MS patients throughout the year and within the hypovitaminosis
level (< 37 nmol/L) in 30% of MS patients at some time of the year.
During MS-relapses, 25(OH)D levels were lower than in remission, but mostly
within the reference range observed in relation with normal bone metabolism.
We conclude that the vitamin D stores in most MS patients are adequate
for their normal bone metabolism. However, lower vitamin D levels during
MS relapses than in remission suggest that vitamin D could be involved
in the regulation of the clinical disease activity of MS. The optimal
serum levels of vitamin D for the regulation of immune responses remain
to be determined.
PMID: 15957505 [PubMed - indexed for MEDLINE]
in the outbreaks in patients with multiple sclerosis]
[Article in Spanish]
J , Prieto
JM , Dapena-Bolano
D , Iglesias-Gomez
S , Noya-Garcia
M , Lema
Servicio de Neurologia, Hospital Clinico Universitario de Santiago de
Compostela, A coruna, Spain .
INTRODUCTION: It has been suggested that there is an environmental factor
at play in the aetiology and pathogenesis of multiple sclerosis (MS) that
acts as an essential component of the disease process, and a number of
studies also point to a relationship between the seasons of the year and
the appearance of outbreaks. AIMS: Our aim was to study the possible relation
between seasonal variations and the appearance of outbreaks in patients
with relapsing-remitting forms of MS. PATIENTS AND METHODS: We studied
31 patients over the period between 1997 and 2002 and calculated the monthly
and quarterly rate of incidence of outbreaks. The statistical evaluation
of the results was performed by applying the Chi-squared test. RESULTS:
We observed a higher incidence of outbreaks in the summer months (more
in June) and a lower incidence in winter (less in December), with statistically
significant differences. CONCLUSIONS: In our patients, outbreaks of MS
are related to seasonal variations, with a higher number in the warmer
months and fewer in the colder months.
PMID: 15849671 [PubMed - indexed for MEDLINE]
in exacerbations and MRI parameters in relapsing-remitting multiple sclerosis.
JA , Feng
Department of Molecular and Experimental Medicine, The Scripps Research
Institute, La Jolla ,
Environmental factors may be involved in the etiology of multiple sclerosis
(MS). We investigate prevalence of exacerbations and MRI findings in a
cohort of relapsing-remitting multiple sclerosis patients, for evidence
of seasonal variation or cyclic trends. We find only weak evidence of
seasonality in our data. Differences in reports of seasonal variation
in multiple sclerosis disease activity may be due to regional climatic
differences or other geographic variables that change with latitude as
well as genetic predisposition.
Timing of birth and
risk of multiple sclerosis: population based study.
CJ , Dyment
DA , Sadovnick
AD , Rothwell
PM , Murray
TJ , Ebers
GC ; Canadian
Collaborative Study Group .
Department of Biostatistics, University
Arbor , MI
OBJECTIVES: To determine if risk of multiple sclerosis (MS) is associated
with month of birth in countries in the northern hemisphere and if factors
related to month of birth interact with genetic risk. DESIGN: Population
based study with population and family based controls and a retrospective
cohort identified from death certificates. A post hoc pooled analysis
was carried out for large northern datasets including Sweden
. SETTING: 19 MS clinics in major cities
across Canada (Canadian collaborative project on the genetic susceptibility
to multiple sclerosis); incident cases of MS from a population based study
in the Lothian and Border regions of Scotland; and death records from
the UK Registrar General. POPULATIONS: 17,874 Canadian patients and 11,502
British patients with multiple sclerosis. MAIN OUTCOME MEASURE: Diagnosis
of multiple sclerosis. RESULTS: In Canada
(n = 17,874) significantly fewer patients
with MS were born in November compared with controls from the population
census and unaffected siblings. These observations were confirmed in a
dataset of British patients (n = 11, 502), in which there was also an
increase in the number of births in May. A pooled analysis of datasets
from Canada ,
Great Britain ,
(n = 42,045) showed that significantly fewer (8.5%) people with MS were
born in November and significantly more (9.1%) were born in May. For recent
incident data, the effect of month of birth was most evident in Scotland
, where MS prevalence is the highest.
CONCLUSIONS: Month of birth and risk of MS are associated, more so in
familial cases, implying interactions between genes and environment that
are related to climate. Such interactions may act during gestation or
shortly after birth in individuals born in the northern countries studied.
Why we should offer
routine vitamin D supplementation in pregnancy and childhood to prevent
Department of Neurology, Institute of Neurological Sciences, 1345
Govan Road, Glasgow G51
4TF , UK
Multiple sclerosis (MS) is a demyelinating disease of the central nervous
system that runs a chronic course and disables young people. The disease
is more prevalent in the geographic areas that are farthest from the equator.
No form of treatment is known to be effective in preventing MS or its
disabling complications. A number of epidemiological studies have shown
a protective effect of exposure to sunlight during early life and a recent
longitudinal study confirmed that vitamin D supplementation reduced life-time
prevalence of MS in women. Very little is known regarding the role of
vitamin D on the developing brain but experimental data suggest that cerebral
white matter is vitamin D responsive and oligodendrocytes in the brain
and spinal cord and express vitamin D receptors. It is possible that differentiation
and axonal adhesion of oligodendrocytes are influenced by vitamin D level
during brain development and a relative lack of vitamin D may increase
oligodendroglial apoptosis. The age effect of migration on susceptibility
to develop MS could be explained by a role of vitamin D on brain development.
In areas of high MS prevalence, dietary supplementation of vitamin D in
early life may reduce the incidence of MS. In addition, like folic acid,
vitamin D supplementation should also be routinely recommended in pregnancy.
Prevention of MS by modifying an important environmental factor (sunlight
exposure and vitamin D level) offers a practical and cost-effective way
to reduce the burden of the disease in the future generations.
PMID: 15617877 [PubMed - indexed for MEDLINE]
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