Another piece of research attached. This time they conclude that the risk of ms is reduced if you have lots of younger siblings.
Again, one has to wonder what use this is to those who have ms. Given other research findings you really don't want to be a female, born in May and a single child! (although I am male, born in March and have a twin sister)
HAVING lots of younger brothers and sisters significantly reduces the chances of suffering multiple sclerosis later in life, a study has found.
However, the effect works only if the age gap is small. The key is to have several younger siblings before you reach the age of 6 — the implication is that exposure to childhood infections helps the immune system to develop properly.
MS is an autoimmune disease, caused by the immune system turning against its host and destroying the myelin sheath that surrounds nerve fibres. This is more likely to happen, the study suggests, if a child at a key stage of development is not exposed to infections from younger siblings. The study was carried out by a team led by Anne-Louise Ponsonby, from the Australian National University in Canberra.
The researchers compared the family patterns of 136 adult MS patients from Tasmania with 272 controls.
They found that people who developed MS, which normally appears between the ages of 20 and 40, are most likely to have been single children.
Among those who did have brothers and sisters, no benefit was found if the siblings were older. If they were younger, a clear reduction in the risk of MS was found. If, by the age of 6, children had one younger sibling, their risk of MS was reduced by 30 per cent; if they had two, risk was reduced by 67 per cent, the team reports in Journal of the American Medical Association.
In addition, the greater the exposure to younger siblings, the later the onset of the disease. However, there was no benefit in having older brothers and sisters, or if the age gap was greater than six years.MS has become commoner over the same period that childhood infections have become rarer, leading to the suggestion, first made almost 40 years ago, that the disease results from the postponement of early life infections.
Sometimes called the hygiene hypothesis, the idea is that increasing cleanliness and absence of disease has led to the rise of several autoimmune diseases, including asthma, arthritis and now MS. This new study lends support to the idea. The team also examined whether exposure to sunshine had any effect. MS is much more common in northerly climates, suggesting that exposure to light is one trigger for the proper development of the immune system. The team took no account of contacts with younger children that might be made in a nursery, or through shared childcare. As they point out, such patterns of childcare were uncommon in Tasmania when this group of adults were children. Nevertheless, the logic suggests that children who mix with lots of others at nurseries from an early age are likely to benefit from it. About 85,000 people in Britain suffer from MS, and it is the most common potentially disabling condition of the central nervous system affecting young adults in the West.