Study: Arthritic parents better chance autistic kids

Post Reply New Topic

Men and women with rheumatoid arthritis are at increased risk of having a child with autism, according to a large study based on medical records from Denmark1. By linking the risk to both parents, the new work hints that autism and arthritis share genetic roots.

Rheumatoid arthritis is a condition in which the immune system attacks the membranes around the joints.

Previous studies have linked this and other immune conditions in pregnant women to autism risk in their children. Another new study suggests that the immune environment in the womb influences autism severity2.

The rheumatoid arthritis study is the first to link the condition in fathers to autism risk.

Mørch’s team gathered data from national healthcare and birth registries for nearly 2 million children born from 1977 to 2008, and their parents. Of these children, 13,556 have mothers with rheumatoid arthritis and 6,330 have fathers with the condition. (Rheumatoid arthritis is more common in women than in men.) Some parents had the condition before the child was born; others developed it later.

A total of 8,985 children in the study have autism. Of these children, 81 have a mother with rheumatoid arthritis and 39 have a father with rheumatoid arthritis. The researchers found that women and men with rheumatoid arthritis both have about a 30 percent greater risk of having a child with autism than parents without the condition. The researchers did not calculate the absolute risk for each scenario.

The results held up even when the researchers limited their analysis to parents diagnosed with rheumatoid arthritis after the birth of their child. They appeared 9 October in the Journal of the American Academy of Child and Adolescent Psychiatry.

Fewer than 10 children in the study have mothers who had rheumatoid arthritis before the children’s birth. So the researchers were unable to study that subgroup.

In their study, Guastella and his colleagues analyzed data for 220 children with autism and their families in an autism registry in Western Australia. They found that children with autism born to mothers with allergies or asthma have more severe social deficits than those whose mothers have no history of immune conditions. The findings were based on scores on a parent questionnaire called the Social Responsiveness Scale.

The results suggest that having certain immune conditions during pregnancy increases autism severity. They appeared 10 October in Molecular Psychiatry.

But the study cannot tease apart the effects of immune activity during pregnancy and those of a shared genetic predisposition to autism and asthma or allergy. “The most critical thing we don’t know is how actively they were wheezing or itching while they were pregnant,” Diamond says.

The researchers found no link between autoimmune conditions such as rheumatoid arthritis in the mother and autism severity in the child. However, the study may have been too small to reveal a connection, Guastella says. Only 30 of the mothers have an autoimmune condition, and just 16 of them were diagnosed prior to the birth of their child with autism.

The Australian and the Danish databases don’t contain the data needed to determine how much genetics or the environment contributes to the link between autism and immune conditions. Studies that incorporate medical records with genetic tests and measures of immune activity before, during and after pregnancy could help to fill in these gaps.