A group of researchers from Germany and the US has found that both ageing and depression are associated with changes in a single gene.
It can be regulated by the addition or removal of methyl (CH3) groups from an area of the gene called FKBP5.
The researchers found that ageing can decrease the methylation process, causing the FKBP5 gene to be over-expressed.
They also found that when someone is depressed, the demethylation process is accelerated even further.
"We found that both ageing and depression seem to lead to changes in how DNA is processed, and that this can control the expression of genes that regulate how we respond to stress," said lead researcher Anthony Zannas from the Max Planck Institute of Psychiatry, Munich, in Germany.
"These changes are associated with increased inflammation, and we believe that this may lead to the increased risk for several ageing related diseases such as cardiovascular diseases and neuropsychiatric disorders," he added.
The FKBP5 gene is found on chromosome 6 in humans.
The work was presented at the European College of Neuropsychopharmacology (ECNP) Congress in Berlin recently.