Why are people from big families at greater risk of a stroke?
Babies who suffer severe diarrhoea in the first few months of their lives could be at greater risk of suffering a stroke many years later.
New research published by Bristol’s Children of the 90s study shows how the small proportion of babies who were so ill they had to be taken to hospital for dehydration appeared to have higher blood pressure at the age of 7.
These results are consistent with earlier findings that people from big families appear to be at greater risk of suffering a haemorrhagic stroke later in life. It may be because as infants they were at greater risk of catching tummy bugs from their brothers and sisters.
It is already known that rates of stroke and high blood pressure have been declining in the developing world – a reduction that fits with declining rates of infant mortality 70 years ago.
Previous research has already shown that early life factors – such as the number of siblings, or the death of a brother or sister in infancy – are also related to the risk of stroke in later life.
The researchers realised that one thing in common with all these factors was greater risk of infant diarrhoea.
The report’s author Professor George Davey Smith suggests that when babies suffer dehydration – it could be that their system helps them to survive a further episode of sudden fluid loss by retaining salt. But that same mechanism that leads to a survival advantage in infancy would put them at risk of higher blood pressure, and hence stroke, later in life.
He says: ”Our date are both intriguing and inconclusive, given the small number of individuals in this case. Repeating this study in places with higher rates of dehydration could provide data to test our hypothesis.
“If established, the link between diarrhoea in infancy and later blood pressure could explain the declining trend in blood pressure and haemorrhagic stroke, and some of the differences between countries in risk of haemorrhagic stroke”.
Academic paper reference
Could dehydration in infancy lead to high blood pressure? George Davey Smith, Sam Leary, Andy Ness, and the ALSPAC Study Team. Journal of Epidemiology and Community Health 2006 Volume 60 ps 142-3 doi:10.1136/jech.2005.040006
Notes:
ALSPAC The Avon Longitudinal Study of Parents and Children (also known as Children of the 90s) is a unique ongoing research project based in the University of Bristol. It enrolled 14,000 mothers during pregnancy in 1991-2 and has followed most of the children and parents in minute detail ever since.