The daughters of women exposed to childhood trauma are at increased risk for serious psychiatric disorders, a new study concludes.
Researchers studied 46,877 Finnish children who were evacuated to Sweden during World War II, between 1940 and 1944. They tracked the health of their 93,391 male and female offspring born from 1950 to 2010.
The study, in JAMA Psychiatry, found that female children of mothers who had been evacuated to Sweden were twice as likely to be hospitalized for a psychiatric illness as their female cousins who had not been evacuated, and more than four times as likely to have depression or bipolar disorder.
But there was no effect among male children, and no effect among children of either sex born to fathers who had been evacuated.
The most obvious explanation would be that girls inherited their mental illness from their mothers, but the researchers controlled for parental psychiatric disorder and the finding still held.
The lead author, Torsten Santavirta, an associate professor of economics at Uppsala University, said that it is possible that traumatic events cause changes in gene expression that can then be inherited, but the researchers did not have access to genetic information.