Depression may speed up DNA ageing

Severe depression
speeds up the ageing process of our cells, researchers have found.

People who
have a history of major depression are known to be at greater risk of diseases
like cancer, diabetes and heart disease. This was primarily thought to be down
to lifestyle factors like smoking or lack of exercise but a study published in
the journal Molecular Psychiatry suggests that depressive illness might have an
additional, more direct effect.

Dr Josine
Verhoeven, from the VU Medical Centre in the Netherlands and colleagues in the
USA say that their work 'provides convincing evidence that depression is
associated with several years of biological ageing, especially among those with
the most severe and chronic symptoms'.

The researchers
analysed the blood cells of 2,407 volunteers: over a third of participants currently
had major depressive disorder, a third had experienced it in the past and the rest had
never had depression.

The
scientists were particularly interested in the cap-like structures on the end
of chromosomes called telomeres.

Telomeres
work to stop the loss of genetic material every time a cell divides, but shorten
with every division and become less able to protect the DNA. In this way,
telomere length is thought to represent the biological age of the cell and
studies suggest that people with shorter telomeres are more likely to have
health problems.

In this
study, people who were currently depressed or had a history of depression had
significantly shorter telomeres in their cells than the other volunteers. This
was true even when the researchers controlled for the effect of lifestyle
factors. There was also a link between severity and duration of depression and
telomere shortness.

In their
paper, the researchers suggest that telomere shortening is accelerated as a
consequence of a stress reaction brought about by major depression.

However, telomere
length is an imperfect indicator of overall health. Talking to the BBC, Dr Anna
Phillips, a health psychologist at the University of Birmingham who was not
involved in the study, said that it does not consistently predict other
key outcomes such as death risk.