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Autism Risk Linked to Older Fathers at Age 40

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Autism is classified as a neurodevelopmental disorder that manifests itself in markedly abnormal social interaction, communication ability, patterns of interests, and patterns of behavior. Autism occurs in as many as one child in 166 in the United States. However, the National Institute of Mental Health gives a more conservative estimate of one in 1000. For families that already have one autistic child, the odds of a second autistic child may be as high as one in twenty. Although autism is about 3 to 4 times more common in boys, girls with the disorder tend to have more severe symptoms and greater cognitive impairment. Diagnosis is based on a list of psychiatric criteria, and a series of standardized clinical tests may also be used.

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Children fathered by men at age 40 and older have a higher risk of developing autism, possibly because of mutations or other genetic changes, according to new research.

The study "provides the first convincing evidence that advanced paternal age is a risk factor for autism spectrum disorder," said the authors from Mount Sinai School of Medicine, New York, and the Institute of Psychiatry, King's College London.

The findings were based on a look at thousands of children born in Israel during the 1980s. All males and three-fourths of the females born in the time period involved were checked by Israeli draft officials at age 17 and any psychiatric disorders were recorded.

"Offspring of men 40 years or older were 5.75 times more likely to have (autism disorders) compared with offspring of men younger than 30 years," said the study published in the Archives of General Psychiatry.
"Advancing maternal age showed no association," it added.
Autism can cause symptoms ranging from social isolation to repetitive and damaging behaviours and sometimes mental retardation.

The problem has become increasingly common, affecting 50 in every 10,000 children in the United States, in part due to greater awareness and changes in diagnoses, the study said.
Typically, developing infants are social beings—early in life they do such things as gaze at people, turn toward voices, grasp a finger, and even smile. In contrast, most autistic children prefer objects to faces and seem to have tremendous difficulty learning to engage in the give-and-take of everyday human interaction. Even in the first few months of life, many seem indifferent to other people because they avoid eye contact and do not interact with them as often as non-autistic children.

Autistic children often appear to prefer being alone to the company of others and may passively accept such things as hugs and cuddling without reciprocating, or resist attention altogether. Later, they seldom seek comfort from others or respond to parents' displays of anger or affection in a typical way. Research has suggested that although autistic children are attached to their parents, their expression of this attachment may be unusual and difficult to interpret. Parents who looked forward to the joys of cuddling, teaching, and playing with their child may feel crushed by this lack of expected attachment behavior.

The report said several genetic mechanisms might be behind the paternal age association found, including spontaneous mutations in sperm-producing cells.