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Older child’s autism increases siblings’ risk

Children who have an older sibling with an autism spectrum disorder are nearly seven times more likely to be diagnosed with autism than those whose older siblings don’t have the disorder, a Danish study found.

Researchers from Aarhus University looked at data from about 1.5 million children born between 1980 and 2004 who had at least one full or half-sibling. Over 13,000 of the children had been diagnosed with autism, including 276 children who had an older sibling with the disorder.

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The study found a 7 percent likelihood of a younger child being diagnosed with autism if their older full sibling had the disorder.

The risk was smaller among half-siblings. Among children with the same mother, the younger half-sibling was twice as likely to be diagnosed with autism if the older one was diagnosed with the disorder. There was no heightened risk among paternally linked half-siblings.

The findings suggest that the mother’s genetics, lifestyle during pregnancy, or her environmental exposures may play a role in her child’s risk for autism, the researchers wrote.

BOTTOM LINE: Children who have an older sibling with an autism spectrum disorder are nearly seven times more likely to be diagnosed with autism than those whose older siblings don’t have the disorder.

CAUTION: The study highlights the average risk and may not be indicative of risk in all families. The risk may also differ among children of other nationalities.

WHERE TO FIND IT: JAMA Pediatrics, Aug. 21

BU explores effects of repeated brain trauma

Athletes with a brain disease linked to repeated head trauma may exhibit altered mood and behavior as their first symptoms, or memory and thinking problems, Boston University researchers found. The study may help to diagnose the disease before death.

The study involved 36 male football and hockey players, wrestlers, and boxers between ages 17 and 98 who were posthumously diagnosed with a neurodegenerative disease called chronic traumatic encephalopathy, or CTE.

The researchers interviewed the athletes’ family members, who reported that 22 of the athletes initially exhibited mood or behavior problems, at an average age of 35. Eleven had memory and thinking problems as their first symptoms, but they didn’t appear until age 59 on average. Three of the athletes showed no symptoms of the disease before their death. The study is the largest to date looking at the effects of CTE.

BOTTOM LINE: Some athletes with a brain disease linked to repeated head trauma experience altered mood and behavior as their first symptoms; others have memory and thinking impairments.

CAUTIONS: The study was small and did not compare the subjects to former athletes without CTE. Reports of symptoms from family members may not have been entirely accurate.

WHERE TO FIND IT: Neurology, Aug. 21

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