Why do we get older? Science fights against time to reveal and postpone the natural process of life

Each year, consumers spend about $62 billion on anti-aging treatments, according to some estimates. But although skin creams, hair dyes and Botox can make a person look younger, none of them can turn back time.

Scientists are studying the biological causes of aging in the hope that tools will be available to slow or stop its visible signs and, more importantly, the diseases associated with it. These underlying mechanisms are often called “indicators of aging.” Many of them fall into two broad categories: general wear and tear at the cellular level and a decreased ability of the body to get rid of old or dysfunctional cells and proteins.

Professor and researcher Linda Partridge, from the Department of Biological Sciences at the University of California, explained, “Indicators of aging are important because they involve processes that do not work properly during aging, and if they were reversed, it would be possible for us to live longer or healthier lives as we age.” . University College London, which helped develop the conceptual basis for these indicators.

The New York Times asked experts on signs of aging about how they cause disease and how scientists are trying to change them. We have selected two major problems from the list: corrosion and disposal problems.

He wears

Many age-related changes occur because our cells, and even our genes, become damaged and behave inappropriately as we age.

Problems with DNA

Although we can think of our genes as being programmed from birth, DNA accumulates changes over the years. Sometimes errors are introduced during cell division, while others arise spontaneously, such as a typo that occurs when DNA is copied and pasted from one cell to another. Mutations may also occur as a result of environmental exposures, such as ultraviolet radiation from the sun.

Our cells have mechanisms to repair these genetic mutations, but their effectiveness decreases with age, which means errors can accumulate. Scientists don't know exactly why DNA repair systems deteriorate. “It's the million-dollar question. The only thing we know is that its efficiency decreases with age,” said Andrew Dehlen, a professor of molecular and cell biology at the University of California, Berkeley.

The main result of this is that the cells stop working properly and are classified as junk (more on this later). In the worst-case scenario, mutations can occur in tumor-suppressing genes, leading to the development of cancer.

Chromosomal problems

Each time a cell reproduces and its DNA is copied, the ends of its chromosomes shorten slightly. These special parts of the genome are called telomeres, and are often compared to the plastic ends of a shoelace, preventing them from fraying.

When a cell's telomeres become too short, it stops dividing. This process is considered healthy when we are young because it prevents cells from multiplying indefinitely and turning into cancer cells. However, as we age, telomere shortening becomes a problem, especially in stem cells, which the body uses to replace skin, blood, and other tissues.

They have a special mechanism to combat this, but they eventually lose their telomeres. “When this happens, they can no longer divide, and the stem cell pool is lost,” says Delin.

The depletion of these cells contributes significantly to the appearance of some physical signs of aging, such as gray hair and thin, less elastic skin. Some skin cosmetics claim to rejuvenate stem cells, but there is not enough evidence of their effectiveness.

Problems with mitochondria

An essential component of cellular health is energy production, which occurs in the mitochondria, the cellular power plant. As we age, these organelles no longer work as well as they once did, and become less efficient, thus generating less energy. “The effectiveness of all other cellular processes is compromised when you don't have enough energy,” said Verdin, who works for two anti-aging drug companies.

According to Delin, changes in cell energy levels also affect other aspects of cellular health, such as epigenetics. Damaged mitochondria can also leave the cell and cause inflammation, another aspect of aging linked to many chronic diseases.

Regular exercise — experts' top recommendations for aging well — is one of the best ways to improve mitochondrial health.

Waste disposal problems

As a result of the above problems, not only do defective cells accumulate with age, but the way the body gets rid of them also deteriorates.

Problems eliminating dysfunctional cells

One of the most important ways to deal with dysfunctional cells is to transition them into a state known as senescence. They stop dividing and begin secreting inflammatory chemicals that signal the immune system to get rid of them.

Normally, this isn't a problem – in fact, it's a necessary part of normal cell renewal – but as we age, two things happen. First, there are more cells that need to be eliminated. Second, the removal system begins to fail. As a result, senescent cells accumulate, causing more and more inflammation.

Problems eliminating bad proteins

Most cells perform their functions through the proteins they produce. If DNA is the blueprint for a house and cells build it, then proteins are the wood, nails and plasterboard.

It is common for them to become damaged – often called misfolded proteins – and there are many ways to repair them. But again, these processes begin to fail as we age, and faulty proteins accumulate and cause problems.

One notorious disease linked to misfolded proteins is Alzheimer's disease, in which amyloid and tau – brain proteins – form plaques and tangles in the brain.