(Agencies)
Updated: 2008-02-05 12:31

Nurture and nature

"What we think these days is there isn't such a divide between nature and nurture," Dr. Kathryn Abel of the Centre for Women's Mental Health Research at Britain's University of Manchester said in a telephone interview.

Abel's schizophrenia study looked at 1.38 million babies born in Denmark between 1973 and 1995. Her team found the risk of schizophrenia was two-thirds greater among offspring whose mothers experienced the death of a relative during the first trimester.

The link disappeared after the first three months, however, perhaps because barriers are built up between mother and fetus later on that protect the unborn baby from stress hormones released by the mother.

Abel said it was possible the mother's hormones may either have a direct impact on development of the fetus brain or affect it indirectly by altering the activity of certain genes.

Schizophrenia is known to run in some families, indicating a genetic component to the disease, yet 90 percent of cases are still classed as nonfamilial or sporadic.

The new study found the association between a family death and the risk of schizophrenia was only significant in this sporadic setting, where a child's parents, grandparents or siblings had no history of mental illness.

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