Dom 08 Feb 2015
LA NASCITA PREMATURA. SUE CONSEGUENZE NEUROLOGICHE A LUNGO TERMINE
Neuroscience: The brain, interrupted
Premature birth lasting consequences
Babies are increasingly surviving premature birth — but researchers are only beginning to understand the lasting consequences for their mental development
Prematurity — also called pre-term birth — is extremely common. According to World Health Organization statistics from 2012, more than one in 10 babies — around 15 million in total — are born prematurely each year. The great majority are born between 32 and 37 weeks of gestation, but 1.6 million are born between 28 and 32 weeks and 780,000 are born 'extremely pre-term', before 28 weeks (see 'Born too soon').
Just a few studies have so far followed up the long-term fate of premature babies, because it is time-consuming and expensive to track them with sophisticated cognitive and behavioural tests over many years.
One of the first studies to show the extent of developmental problems was EPIPAGE, which looked at a cohort of all live births between 22 and 32 weeks of gestation from 9 regions of France in 1997, and a reference group of 664 full-term babies
Larroque, B. et al. Neurodevelopmental disabilities and special care of 5-year-old children born before 33 weeks of gestation (the EPIPAGE study): a longitudinal cohort study Lancet 371, 813–820 (2008)
The effects seem to continue into adulthood. Developmental psychologist Dieter Wolke led an unusual study of hundreds of children born between 26 and 31 weeks of gestation in Bavaria in the mid-1980s. He assessed them at six years old, and again at 26 years.
Last year, he reported that most of those who had cognitive problems as children still had them as adults: one-quarter of them had moderate to severe cognitive deficits, and half had mild cognitive deficits. Most of those who experienced problems had short attention spans, and as a group they tended to underachieve academically and career-wise.
Too much too soon
Scientists suspect that when the brain is forced to carry out a crucial part of its development while the child is in the outside world instead of a warm, watery womb, it receives inappropriate signals from the environment that affect how its neurons are linked into networks.
Pioneering brain-scanning studies support the idea that altered networks play a part in cognitive problems. Hüppi's Swiss collaboration looked at 52 six-year-olds who had been born prematurely, using MRI scans optimized to reveal tracts of neurons connecting brain regions. Compared with children born at term, the premature children's neuronal tracts were organized less efficiently, often taking a more meandering path.
In another study, neonatologist Jeffrey Neil, then at St. Louis Children's Hospital in Missouri, and his team used functional MRI to study the premature brain at rest.
Cereb. Cortex (2014).
In France, EPIPAGE 2 is now running, and has recruited more than 4,200 premature babies from all over the country.. In the United Kingdom, a team led by neonatologist David Edwards of King's College London has launched a study that will track children from their time in utero until they are two years old, collecting brain scans and blood samples along the way. Some of these children will inevitably be born prematurely, and the plan is to identify molecular signatures that might predict which of those infants are particularly vulnerable, or resistant, to altered neurodevelopment.