Linked to Father's Age
YORK (Reuters Health) - Women may hear the symbolic ticking of
their biological clocks as they approach the age of 40, but men
might want to listen more closely to their own, researchers suggest.
A recent study
found that fathers aged 50 and older were nearly three times more
likely than men younger than 25 to have a child with schizophrenia.
Men aged 45 to 49 were about twice as likely to have a child with
the disorder, regardless of the mother's age.
published in the April issue of Archives of General Psychiatry,
support previous studies demonstrating a link between older fathers
and other gene-related disorders. If confirmed, they could shape
strategies to search for genes that may play a role in schizophrenia,
Dr. Dolores Malaspina of Columbia University in New York City
and her colleagues write.
diseases are related to new mutations and paternal age, but this
is the first demonstration of this effect for a psychiatric disease,''
Malaspina told Reuters Health in an interview. ``This suggests
that many nonfamilial cases of schizophrenia, previously presumed
to reflect a greater contribution of environmental causes, might
instead be genetic.''
is a severe brain disorder that alters a person's perceptions
of reality, emotions and thought processes. Symptoms of the disorder,
which affects about 1% of the world's population, typically surface
during the late teens and 20s.
causes of the disease are not known, schizophrenia is believed
to arise from a mix of genetic and environmental triggers. Exactly
how the disease is passed along has remained unclear, since it
can reduce the reproductive capacity of patients.
whether new mutations--rather than those passed from generation
to generation--played a role, the researchers analyzed rates of
schizophrenia among a group of nearly 88,000 children in relation
to their parents' ages.
The risk of
the disorder rose in tandem with the father's age but was not
significantly tied to the age of the mother, results show. The
rate of the disorder among children born to men younger than age
25 was 2.5 per 1,000 children. It rose to 4.4 per 1,000 children
for fathers aged 35 to 40, and to 11.4 per 1,000 children for
dads 50 and older.
explain that in the process of constantly dividing, sperm-producing
cells become more vulnerable to mutation. These mutations can
be passed along to offspring.
a cell divides there is a chance for an error, and these errors
accumulate in men as they age,'' Malaspina told Reuters Health.
that male sperm cells are copied every 16 days and undergo 200
divisions by age 20 and 660 divisions by age 40.
``If new mutations
play a role in schizophrenia vulnerability then we would expect
to observe a relationship between schizophrenia and paternal age,''
the authors explain.
estimate that one quarter of schizophrenia cases may be linked
to paternal age, and for the offspring of fathers 50 and older,
two thirds of cases may be attributed to paternal age.
Archives of General Psychiatry April 2001.
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