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Washington D.C., May 8: The prime time for brain development in a child's life is the first year, where the infant spends most of the time asleep. It is the time when neural connections form and sensory memories are encoded.

However, when sleep is disrupted, as occurs more often among children with autism, brain development may be affected, too.

New research led by the University of Washington finds that sleep problems in a baby's first 12 months may not only precede an autism diagnosis but also may be associated with altered growth trajectory in a key part of the brain, the hippocampus.

The study, which was published in the American Journal of Psychiatry, researchers report that in a sample of more than 400 taken of 6- to 12-month-old infants, those who were later diagnosed with autism were more likely to have had difficulty falling asleep.

It also states that this sleep difficulty was associated with altered growth trajectories in the hippocampus.

"The hippocampus is critical for learning and memory, and changes in the size of the hippocampus have been associated with poor sleep in adults and older children.

As many as 80 per cent of the children with autism spectrum disorder have sleep problems," said Annette Estes, director of the UW Autism Center and senior author of the study.

"In our clinical experience, parents have a lot of concerns about their children's sleep, and in our work on early autism intervention, we observed that sleep problems were holding children and families back," added Estes, who is also a UW professor of speech and hearing sciences.

"It could be that altered sleep is part-and-parcel of autism for some children. One clue is that behavioural interventions to improve sleep don't work for all children with autism, even when their parents are doing everything just right. This suggests that there may be a biological component to sleep problems for some children with autism," said Estes.

To consider links among sleep, brain development, and autism, researchers at the IBIS Network looked at MRI scans of 432 infants, surveyed parents about sleep patterns, and measured cognitive functioning using a standardized assessment.

At the outset of the study, infants were classified according to their risk for developing autism: Those who were at higher risk of developing autism -- about two-thirds of the study sample -- had an older sibling who had already been diagnosed.

Infant siblings of children with autism have a 20 per cent chance of developing autism spectrum disorder -- a much higher risk than children in the general population.

In the current study, 127 of the 432 infants were identified as "low risk" at the time the MRI scans were taken because they had no family history of autism.

They later evaluated all the participants at 24 months of age to determine whether they had developed autism. Of the roughly 300 children originally considered "high familial risk," 71 were diagnosed with autism spectrum disorder at that age.

Problems with sleep were more common among the infants later diagnosed with an autism spectrum disorder, as were larger hippocampi. No other subcortical brain structures were affected, including the amygdala, which is responsible for certain emotions and aspects of memory, or the thalamus, a signal transmitter from the spinal cord to the cerebral cortex.

The authors note that while parents reported more sleep difficulties among infants who developed autism compared to those who did not, the differences were very subtle and only observed when looking at group averages across hundreds of infants.

Sleep patterns in the first years of life change rapidly as infants transition from sleeping around the clock to a more adult-like sleep/wake cycle. Until further research is completed, Estes said, it is not possible to interpret challenges with sleep as an early sign of increased risk for autism.

Washington, Jun 30: Researchers in China have discovered a new type of swine flu that is capable of triggering a pandemic, according to a study published Monday in the US science journal PNAS.

Named G4, it is genetically descended from the H1N1 strain that caused a pandemic in 2009.

It possesses "all the essential hallmarks of being highly adapted to infect humans," say the authors, scientists at Chinese universities and China's Center for Disease Control and Prevention.

The researchers then carried out various experiments including on ferrets, which are widely used in flu studies because they experience similar symptoms to humans -- principally fever, coughing and sneezing. 

G4 was observed to be highly infectious, replicating in human cells and causing more serious symptoms in ferrets than other viruses.

Tests also showed that any immunity humans gain from exposure to seasonal flu does not provide protection from G4.

According to blood tests which showed up antibodies created by exposure to the virus, 10.4 percent of swine workers had already been infected.

The tests showed that as many as 4.4 percent of the general population also appeared to have been exposed.

The virus has therefore already passed from animals to humans but there is no evidence yet that it can be passed from human to human -- the scientists' main worry.

"It is of concern that human infection of G4 virus will further human adaptation and increase the risk of a human pandemic," the researchers wrote.

The authors called for urgent measures to monitor people working with pigs.

"The work comes as a salutary reminder that we are constantly at risk of new emergence of zoonotic pathogens and that farmed animals, with which humans have greater contact than with wildlife, may act as the source for important pandemic viruses," said James Wood, head of the department of veterinary medicine at Cambridge University.

A zoonotic infection is caused by a pathogen that has jumped from a non-human animal into a human.