Scientists identify, aim to slow ‘hallmarks of aging’

According to some estimates, consumers spend $62 billion a year on “anti-aging” treatments. But while creams, hair dyes and Botox can give the impression of youth, none of them can roll back the hands of time.

Scientists are working to understand the biological causes of aging in the hope of one day being able to offer tools to slow or stop its visible signs and, more important, age-related diseases. These underlying mechanisms are often called “the hallmarks of aging.” Many fall into two broad categories: general wear and tear on a cellular level, and the body’s decreasing ability to remove old or dysfunctional cells and proteins.

“The crucial thing about the hallmarks is that they are things that go wrong during aging, and if you reverse them,” you stand to live longer or be healthier while you age, said Dame Linda Partridge, a professorial research fellow in the division of biosciences at University College London who helped develop the aging hallmarks framework.

So far, the research has primarily been conducted in animals, but experts are gradually expanding into humans. In the meantime, understanding how aging works can help us put advice and information about the latest “breakthrough” into context, said Venki Ramakrishnan, a biochemist and Nobel laureate who wrote about many of the hallmarks of aging in his new book, Why We Die: The New Science of Aging and the Quest for Immortality.

The New York Times asked experts about the hallmarks of aging, how they can lead to disease and how scientists are attempting to modify them. Not all of the hallmarks are listed here, but two of the main themes — wear and tear, and disposal issues — are highlighted below.

Wear and tear

Many age-related changes start with our cells, and even our genes, acquiring damage and acting up as we get older.

Problems with DNA

While we think of our genes as being set from birth, DNA does accumulate changes over the years. Sometimes errors are introduced when a cell divides, a spontaneous typo emerging when the DNA is copied and pasted from one cell into another. Mutations can also occur as a result of environmental exposures, including ultraviolet radiation from the sun.

Our cells have ways to repair these genetic mutations, but they become less efficient with age, which means the mistakes can pile up. Scientists aren’t exactly sure why our DNA repair mechanisms decline. “That’s a $1 billion question,” said Andrew Dillin, a professor of molecular and cell biology at the University of California, Berkeley. “All we know is that the efficiency goes down with age.”

Problems with the epigenome

Other changes occur through what’s known as epigenetics — chemical modifications to the genome that influence which genes are turned on or off in a cell. Some epigenetic changes occur naturally as we develop, while others are brought on by our environment. Some experts say that epigenetic changes can be used to determine a person’s “biological age.”

Scientists have discovered that many of the epigenetic mechanisms that help control the activity and even the identity of our cells start to degrade with age. If this happens in too many cells, it can affect organ health and function. For example, epigenetic changes in heart cells can contribute to thickened arteries or a reduced ability for the heart to respond positively to exercise.

There is currently a flurry of antiaging research looking at epigenetic changes because they are more easily reversible than something like DNA mutations, said Dr. Eric Verdin, the president of the Buck Institute for Research on Aging.

Garbage disposal issues

Not only do faulty cells build up with age because of the problems mentioned above, but the body’s way of disposing of them also goes awry.

Problems disposing of bad cells

One of the most important ways malfunctioning cells are dealt with is by relegating them to a state known as senescence. These cells stop dividing, and they start to secrete inflammatory chemicals that signal to the immune system to dispose of them.

Ordinarily, this isn’t a problem — in fact, it’s a necessary part of normal cell turnover — but as we age, two things happen. First, there are more cells that need to be discarded. Second, the disposal system starts to break down. As a result, senescent cells build up, causing ever more inflammation.

Scientists are exploring ways to enhance the disposal of senescent cells with a class of drugs known as senolytics, though the research is still in preliminary stages.

What to do for now

The experts agreed experimental anti-aging therapies are not yet ready for widespread use, though they’re optimistic about the future of the field. “So far, I would say the winds haven’t been particularly quick, but there will be breakthroughs,” Partridge said. For now, she added, the best thing that people can do to age well is adopt healthy lifestyle habits, like exercise and good nutrition.