Depression Accelerates Aging

Why stress makes you old

If a person is stressed for a long time, you can often see the psychological stress in them: They appear gray and tired and even seem to have more wrinkles. For a long time it was unclear whether this subjective impression is deceptive or whether stress actually makes us physically age faster. Among other things, because the processes of cell aging and their influencing factors have only been explored more precisely in recent years. In the meantime, however, it has been shown that psychological stress actually accelerates aging on a cellular level.

Telomeres, the end caps of the chromosomes, here colored white, protect our genetic material during cell division. © NCI / Hesed Padilla-Nash, Thomas Ried

End caps as age indicators

How old a cell or tissue is is shown primarily by its chromosomes. Because every cell division cuts off a piece at the ends of the 46 compact genetic material packages. If there were important genes in these end pieces, the functionality of the cell would quickly be disrupted and it would die after just a few divisions. Fortunately, a special protection mechanism ensures that this does not happen. The ends of the chromosomes carry a kind of buffer: sections of DNA that are tightly interwoven with proteins and contain no coding genes.

These end caps, also called telomeres, are shortened a bit with every cell division, but since they are not absolutely necessary for the cell to function, this does not initially harm. In addition, these end caps are at least partially replenished after the division. The enzyme telomerase supplements part of the missing DNA and thus compensates for the loss. But because this does not happen completely, our telomeres shrink as we age. If they have fallen below a critical length, the days of the cell are numbered: it no longer divides and ultimately dies completely. So far, so well known.

Crying infant © SXC

Sick children stress the chromosomes themselves

In 2004, however, telomere researcher and later Nobel Prize winner Elizabeth Blackburn came across another factor in this complex interplay: stress. In one study, she compared the white blood cells of mothers with healthy and chronically ill children. She wants to know whether the great psychological stress caused by worrying about the sick child is also reflected on the cellular level and thus perhaps explains why stressed people seem to age faster. “Theoretically, psychological stress could influence cell aging in three very different ways,” she explains. "It could change the function or number of defense cells and thus the immune system, it could increase oxidative stress from aggressive molecules or it could impair the activity of the enzyme telomerase."

In fact, two of their three hypotheses are confirmed: In the white blood cells of stressed mothers, there is more damage from aggressive molecules and their telomeres are also shorter - and significantly. On average, the chromosome end caps of these women wear 550 base pairs less than those of their less stressed peers. "Converted to cell aging, this means that your white blood cells are between nine and 17 years older," explains Blackburn.

And researchers have come across this relationship between stress and telomeres again and again in follow-up studies. Similar effects have now also been proven for experiences of violence and neglect in early childhood. "It is always the same, regardless of whether it is for kindergarten children or those over 80, for small samples or studies with several thousand participants," says the researcher. According to popular theory, this effect is due, among other things, to the stress hormone cortisol, which inhibits the action of telomerase and thus prevents adequate repair of the end caps.

Nadja Podbregar
Status: 01/25/2013

January 25, 2013