Children who have experienced violence might really
be older than their years. The DNA of 10-year-olds who experienced violence in
their young lives has been found to show wear and tear normally associated with
aging, a Duke University study has found.
"This is the first time it has
been shown that our telomeres can shorten at a faster rate even at a really
young age, while kids are still experiencing stress," said Idan Shalev, a
post-doctoral researcher in psychology and neuroscience at the Duke Institute
for Genome Sciences & Policy.
Telomeres are special DNA sequences found at the
tips of chromosomes; much like the plastic tips of shoelaces, they prevent DNA
from unraveling. Emerging evidence suggests that telomeres are "master
integrators," connecting stress to biological age and associated diseases.
Telomeres are known to get shorter each time cells
divide, putting a limit on the number of times a given cell can go on dividing.
Smoking, obesity, psychological disorders and stress have been found to
possibly accelerate that process of telomere loss. In that sense, our telomeres
may reflect biological age, not just chronological age.
Previous studies of telomeres and stress had primarily
looked at telomeres in adults as they recalled experiences much earlier in
their lives.
In the new study, Shalev took advantage of the
Environmental-Risk Longitudinal Twin Study led by Duke's Avshalom Caspi and
Terrie Moffitt that has followed 1,100 British families with twins since the
time those twins were born in the 1990s. The twins are now 18-year-old adults,
but the researchers performed the analysis on DNA samples collected when they
were just five and 10 years old. The researchers also know, based on extensive
interviews held with the twins' mothers, which of them experienced some form of
violence in their younger years, including domestic violence, frequent bullying
or physical maltreatment by an adult.
The new report in the journal Molecular Psychiatry
shows that a subset of those children with a history of two or more kinds of
violent exposures have significantly more telomere loss than other children.
Since shorter telomeres have been linked to poorer survival and chronic
disease, this may not bode well for those kids.
"Research on human stress genomics keeps
throwing up amazing new facts about how stress can influence the human genome
and shape our lives," said Caspi, the Edward M. Arnett Professor of
Psychology and Neuroscience.
The findings suggest a mechanism linking cumulative
childhood stress to telomere maintenance and accelerated aging, even at a young
age. It appears to be an important way that childhood stress may get
"under the skin" at the fundamental level of our cells.
"An ounce of prevention is worth a pound of
cure," said Moffitt, who is the Knut Schmidt Nielsen Professor of
Psychology and Neuroscience. "Some of the billions of dollars spent on
diseases of aging such as diabetes, heart disease and dementia might be better
invested in protecting children from harm."
The Duke team plans to further explore the new
findings by measuring the average length of telomeres in the twins now that
they are adults. They'll also repeat the study in a second, older group of
1,000 individuals in the Dunedin Study, who have been under observation since
their birth in the 1970s in New Zealand.
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