American scientists have found that babies from the group with a high risk of developing autism spectrum disorder that was later diagnosed, have problems falling asleep and is associated with a gradual increase in volume of the hippocampus in the development process. This relationship was not detected in children from the low risk group and high risk group without subsequent diagnosis, write the scientists in The American Journal of Psychiatry.
The need for sleep changes with age: if an adult person can survive about seven hours of sleep, the child sleep must be much more. Babies up to a year to sleep about 14-15 hours a day, although this figure may change in the development process: to four months the recommended duration of sleep is about 17 hours, and by year can be reduced to 11-12.
The long sleep is very important for the development of the child, so sleep problems may indicate an unstable development. For example, the reduction of sleep duration often observed in children with autism spectrum disorder, but the reason for such a connection (especially from the point of view of brain development) not much is known.
Catherine Macduff (Katherine MacDuffie) from the University of Washington and her colleagues decided to explore further the relationship between sleep duration at an early age and diagnosed with autism spectrum disorder, as well as to ensure that regulated whether this connection is the anatomical differences of the brain. For this they used MRI scans of the brain 432 young children received in six months, one year and two years.
All participants belonged to three groups depending on whether they were at risk (diagnosed disorder in a family member), and diagnosed if they have autism spectrum disorder. Thus, 71 children from the group with high risk were diagnosed with the disorder at 234 diagnosis was not, and the rest of 127 the risk was low and the disorder was not diagnosed.
In addition to MRI scans, the scientists also gathered data on how do infants problem with going to bed: to do this, parents were asked to fill out a questionnaire about how much their children sleep, is it hard to fall asleep, how often they Wake up at night, easy to sleep back. Based on interviews with scientists exhibited a score from one to seven — the higher it is, the more problems falling asleep experienced by a child.
The resulting survey index correlated significantly with those to which group belonged the child: children who have been diagnosed with autism spectrum disorder, longer could not sleep, than children from groups with high risk but no diagnosed disorders (p = 0.02) and children from groups with low risk (p = 0.001).
After analyzing the MRI data, researchers found that problems falling asleep in infancy and early childhood was associated with increased hippocampal volume, but only in the group of children later diagnosed with autism spectrum disorder (p = 0.006).
The hippocampus plays a very important role in memory formation and other cognitive functions at an early age, and experiments on laboratory animals show that sleep disorders interfere with its proper development. To draw conclusions about causality, the authors refused: in their view, developmental disorders of the hippocampus due to poor sleep could either make the brain vulnerable to the development of autism, or be present initially, and to be a consequence of other factors — how the neurobiological and genetic.
To restore the dream of a six-month infants (out of possible symptoms of autism spectrum disorder) may help in early introduction of complementary feeding: two years ago, scientists foundthat babies who start feeding purees and other foods in addition to breast milk before six months, sleep longer and Wake up less frequently at night.