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The findings offer potential ways to find people at high risk of suicide, and perhaps to treat them and prevent future suicides.
And, the researchers said, they also offer insights into how neglect and abuse can perpetuate unhealthy behaviour through the generations.
Moshe Szyf of McGill University in Montreal and colleagues studied the brains of 18 men who committed suicide and who were also abused or neglected as children, and compared them to 12 men who also died suddenly, but from other causes, and who were not abused, although some had various psychiatric problems such as anxiety disorders.
Findings lead to more questions
They found changes in the genetic material of all 18 suicide victims. The changes were not in the genes themselves, but in the ribosomal RNA, which is the genetic material that makes proteins that in turn make cells function.
These changes involved a chemical process called methylation, a so-called epigenetic change involving the processes of turning genes on and off, they reported in the Public Library of Science journal PLoS ONE.
"The big remaining questions are whether scientists could detect similar changes in blood DNA - which could lead to diagnostic tests - and whether we could design interventions to erase these differences in epigenetic markings," Szyf said in a statement.
Dr Eric Nestler of the University of Texas Southwestern Medical School in Dallas said both drugs and psychotherapy may act to reverse some of these changes.
"Ultimately we believe that a person who gets better from psychotherapy is inducing changes in the brain," Nestler told reporters at a meeting of the American Psychiatric Association in Washington where similar research was discussed.
Parental neglect has huge impact
Szyf's colleague, Michael Meaney, has shown in animals that parental abuse and neglect can affect the brains and behaviour of offspring.
He has studied the brains of rats, for which parental care can be demonstrated in how much the mother grooms her pups.
"You can put two rats on a table and tell which one is raised by a low-licking mother. The one reared by a low-licking mother is more nervous, and fatter," Meaney said in an interview at the Psychiatric Association meeting.
Images of the brain cells of the rats show the brain cells of low-licking mothers have fewer dendrites. These are the strands that help one neuron communicate with another.
Meaney, who also worked on the suicide study, said the research, taken together, demonstrates how early experiences can cause physical changes in the brain.
He said female rats reared by low-licking mothers reached puberty earlier, meaning they had more offspring.
Similar findings are true of humans, who often have children at younger ages when times are stressful. The best way to pass along genes in uncertain times is to have more children, he said. – (Reuters Health)
May 2008
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