| Men age 40 years and older are more likely to have a child develop an autism spectrum disorder than men whose child is born when they are under age 30 years Men age 40 years and older are more likely to have a newborn child develop an autism spectrum disorder than men whose child is born when they are under age 30 years, according to an article in the September issue of Archives of General Psychiatry. Autism and related conditions, known collectively as autism spectrum disorders, have become increasingly common, affecting 50 in every 10,000 children compared with 5 in 10,000 two decades ago. This increase is partially due to higher levels of awareness and changes in diagnosis, but may also reflect a real increase in incidence of autism, according to the authors. Older parental age has previously been linked to abnormalities in brain development of children; however, few studies have effectively examined the effect of mothers' and fathers' ages on autism. Abraham Reichenberg, PhD, of the Mount Sinai School of Medicine, New York, and Institute of Psychiatry, King's College London, and colleagues evaluated children born during the 1980s in Israel. All men and three fourths of the women born in these years were assessed by the draft board at age 17 years, during which time any psychiatric disorders were recorded. Reichenberg and colleagues obtained draft board information and the age of the father for 318,506 individuals; age of the mother was available for 132,271 of those. Of the total of 318,506, 208 (a rate of 6.5 per 10,000) had a diagnosis of autism spectrum disorder, compared with 110 individuals in the group with data for both maternal and paternal age (8.3 per 10,000). Among the paternal age groups of 15 to 29 years, 30 to 39 years, 40 to 49 years and older than 50 years, there were 34 cases, 62 cases, 13 cases and 1 case, respectively, of autism spectrum disorder. Advancing age among fathers was associated with increased risk of autism. This association persisted after researchers controlled for year of birth, socioeconomic status and mother's age: The risk for autism spectrum disorder was nearly 6 times greater among children of men age 40 years and older than those of men 29 years and younger. Older age among mothers was not associated with autism after researchers factored in the effect of the father's age. The authors discussed several possible genetic mechanisms for the paternal age effect, including spontaneous mutations in sperm-producing cells or alterations in genetic "imprinting," which affects gene expression. "It is important to keep in mind, however, that age at paternity is influenced
by the sociocultural environment and varies across societies and over time,"
they continued. "In a given population, a change in the sociocultural environment
could produce a change in paternal age at birth. In theory, it could thereby lead
to a change in the incidence of genetic causes of autism." |