VitalChild - Severe stress during pregnancy linked to higher schizophrenia risk in offspring

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Severe stress during pregnancy linked to higher schizophrenia risk in offspring
Source: Canadianpress Date: 02/05/08

Children born to mothers who experience the death of a close family member during the first trimester of pregnancy appear to have an increased risk of developing schizophrenia later in life, researchers say.
Their study found that dealing with the loss of a close loved one - for instance, a parent or sibling - in early pregnancy boosted the risk of their child developing schizophrenia by 67 per cent, compared with the offspring of mothers who did not undergo such stress.

But co-author Dr. Kathryn Abel, director of the Centre for Women's Mental Health Research at the University of Manchester, cautioned that the finding is an association only, and does not mean that experiencing a severe emotional blow directly causes their child to later become schizophrenic.

"The first thing to say is it's extremely rare, schizophrenia, and that (stress) is absolutely not the only thing that's going to produce schizophrenia in the offspring," Abel said Monday from Manchester, England.

"We know that schizophrenia is a very complex behavioural disorder with very complex causes and there's not going to be ever one cause."

Almost 300,000 Canadians have the neurological disorder to varying degrees. The condition can result in all or some of the following symptoms: delusions and hallucinations, lack of motivation, social withdrawal and thought disorders.

Previous research has suggested that exposure of the developing brain to injury or abnormal neurochemical or hormonal levels may make a child vulnerable to schizophrenia, likely in the presence of an underlying genetic predisposition.

What's perhaps most puzzling about the condition, which has no cure but can respond to drug treatment, is that it typically occurs late in adolescence or early adulthood.

"There have been millions of very, very big brains trying to answer the question of why schizophrenia has this delayed onset, particularly since it's been clear for some time that there's evidence in people with schizophrenia that it's neurodevelopmental in origin," Abel said.

"It may be that schizophrenia takes a long time to develop because something has to happen during puberty to the frontal lobes or the hippocampus or various aspects of the brain we think are involved in the symptoms of schizophrenia to allow the development of the syndrome."

Abel said the delayed-onset notion is not unknown elsewhere in medicine - studies have shown that youngsters with restricted fetal growth have an elevated risk of heart disease, diabetes and high blood pressure in adulthood.

To conduct the study, the researchers analyzed a national registry containing health and family records for more than 1.3 million Danes. Women were linked to close family members using the registry and it was used to determine if any had relatives who died or received a diagnosis of cancer, heart attack or stroke during a mother's pregnancy.

Their children were followed from the 10th birthday through June 30, 2005 or until they died, moved out of the country or developed schizophrenia.

During the study period, the mothers of 21,987 children lost a relative during pregnancy, 14,206 were exposed to a relative's serious illness and 7,331 of the children developed schizophrenia.

While death of a loved one during the first three months of pregnancy was linked to a bumped-up risk for schizophrenia, death of a relative up to six months before or any other time during pregnancy appeared to have no effect on risk, nor did exposure to serious illness in a relative, the study found.

Abel said previous research has shown that children born to women exposed during pregnancy to severe emotional stress from earthquake, famine or war also have an elevated risk of becoming schizophrenic as young adults.

"Chemicals released by the mother's brain in response to stress may have an effect on the fetus's developing brain," the authors suggest. "These effects may be strongest in early pregnancy, when protective barriers between the mother and fetus are not fully constructed."

Chris Summerville, interim CEO of the Schizophrenia Society of Canada, said scientists have believed for some time that "external and internal" stress during fetal development leaves the brain vulnerable to triggers later in life that result in schizophrenia.

The new study, published in Tuesday's issue of the Archives of General Psychiatry, adds one more possible piece towards helping solve the puzzle of schizophrenia, he said.

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