Innholdsfortegnelse for EG18 i New Scientist - The Essential Guides

FOR centuries, humans have sought the fountain of youth, a mythical spring that supposedly rejuvenated anyone who bathed in it or drank its water. The 5th century BC Greek historian Herodotus wrote about it, as did Crusader chroniclers. In the late middle ages it was said to be located on a lost Caribbean island. The fountain of youth is no longer seen as a literal fountain or spring, but the quest for it has never stopped. And no wonder – ageing can be a crushing experience, as the physical and cognitive health we once took for granted inexorably fades, never to return. There are some upsides to ageing, of course, but the simple fact remains that getting older is associated with multiple diseases and, ultimately, death. The good news is…

WHETHER on page, stage or screen, the story of human health and happiness is often presented as an inevitable arc between birth and death. William Shakespeare captured this best with his “seven ages of man”. We enter the world “mewling and puking” as an infant, pass through the awkwardness of childhood and adolescence into our physical and mental prime, before a slow decline. Until recently, science appeared to confirm this view. For many abilities, we seemed to reach our peak well before midlife. But it is now becoming clear that this picture is far too simplistic. FORTIES This is a peak time for emotional intelligence and ability to focus. There are many reasons to feel positive about being over 40. Studies by Laura Germine at Harvard Medical School have included…

THE male “andropause” is much more difficult to study because it is not as obvious as the menopause. In the female menopause, sex hormone levels drop dramatically. Men and some trans women and non-binary people also experience a decline in their dominant sex-related hormone testosterone. This is linked with changes in mood and strength, as well as a loss of libido, coined the “manopause”. The difference, though, is that testosterone levels decline very slowly, at the rate of about 1 per cent per year around the age of 40, and only about 1 to 2 per cent of people report symptoms that are directly related to the drop in the hormone. For these people, testosterone replacement therapies may be offered. For others, the lack of energy and libido that can…

IT HAPPENS to everyone who lives long enough, gradually at first and then suddenly. By the time we are in our 50s, most of us have at least one age-related disease. By 85, almost everybody does, usually several at once. That adds up to a whole heap of trouble – the illnesses that get more common with age include cancer, diabetes, cataracts, osteoarthritis, dementia, kidney failure, cirrhosis of the liver and cardiovascular disease. There are dozens more, perhaps as many as 100. Assuming that nothing else kills us, one or more of them eventually will. Age-related diseases are among the world’s leading cause of morbidity and death. Cardiovascular disease is the world’s biggest killer, accounting for 17.9 million deaths annually, about 30 per cent of the total. Cancer is second…

ON HER 120th birthday, Jeanne Calment – generally regarded as the oldest person ever to have lived – proved she still had her wits about her: “I’ve only got one wrinkle,” she wisecracked, “and I’m sitting on it.” Funny, but untrue. The Frenchwoman was, by then, extremely wrinkly. On the Fitzpatrick Scale used to assess the progression of wrinkliness she would have been a shoo-in for the top category, with deep horizontal lines, extremely saggy skin, prominent jowls and a flaccid double chin. Quelle surprise. She may not have been as old as she claimed, but she was at least 97. Anybody who lives to 100 or so can expect the same. Historically, this has been regarded by many as a purely cosmetic problem. Wrinkles, sags and bags are, in…

AGE is a slippery concept. We tend to think of it as the number of birthdays we have clocked up – our chronological age. But this is just one indicator of the passage of time. We also have a biological age, a measure of how quickly the cells in our body are deteriorating compared with the general population. And these two figures don’t always match up. We all know people who look young for their age, or folks who seem prematurely wizened. Even in an individual, different parts of the body can age at different speeds. By examining how chronological age lines up with biological age across the population, researchers are starting to pin down how these two measures should sync up – and what it means for how long…

ONE in two people will receive a cancer diagnosis in their lives, and even though survival rates are improving, a third of those will die from it. Half of diagnoses are in people over 70, according to Cancer Research UK. The reason for its clear link to ageing is not hard to fathom: cancer is caused by mutations in DNA, and these accumulate as we age – partly as a function of time but also because DNA protection and repair systems deteriorate with age. Cancer is not one disease but many. There are more than 200 forms. But all of them are caused by the same underlying pathology: cells in the body acquiring the ability to grow and proliferate uncontrollably. Deaths from cancer are usually caused by secondary tumours, which…

CARDIOVASCULAR disease – especially heart attacks and stroke – is a major killer, and one of its leading underlying causes is high blood pressure. One in four adults have this condition, known in medical circles as hypertension. That adds up to around a billion cases worldwide and its prevalence is rising globally, especially in lower-income countries. It is linked with stress and age and occurs more often among certain groups of people, including smokers, heavy drinkers and those who are pregnant, inactive or overweight. A blood pressure reading consists of two numbers, measured in a unit called millimetres of mercury (mmHg). The first indicates systolic pressure (the pressure at which the heart pumps blood through the arteries) and the second diastolic (the blood pressure between heartbeats). Anything between 90/60 mmHg…

IF YOU want to live a longer and healthier life, your future should be full of beans, both literally and metaphorically. There will also be a lot of vegetables, no meat, long periods of hunger and hardly any alcohol. But in return for this dietary discipline, your life will also be significantly longer and sprightlier. A 50-year-old today can expect to live for another 30 years. But through dietary changes they could gain an extra decade and live in good health into their 90s. This “longevity diet” isn’t just the latest fad, it is the product of more than a human lifespan of scientific research. And it isn’t merely designed to prevent illness, but to actually slow down the ageing process. It is a no-brainer to say that our diets…

ONE of the consequences of a fading immune system is the accumulation of senescent cells, which produce toxic compounds and are a direct driver of age-related disease. Drugs are in development, but while we wait on these senolytics and senomoldulators, other options already exist. Exercise has been shown to reduce the burden of senescent cells in skeletal muscle and fat tissue, though a recent study found that the benefits only accrue from a gruelling session of high-intensity exercise. Caloric restriction is also a senolytic. Senescent skin cells are a significant problem and may be a driver of whole-body ageing. Whether that is true remains to be seen. But there is still good reason to want to slow down the skin-ageing process. Aged skin is worse than young skin at pretty…

ONE key determinant of healthy (or unhealthy) ageing is how old people feel. As we found in Chapter 2, “subjective age” has a real impact on health and longevity. You can take control of it. ← See page 34 for more on subjective age There are lifestyle changes we can all make to shift it down. The fact that the biggest influence on how old we feel is physical health is very actionable. Exercise to improve fitness and dietary changes to improve blood pressure are easy ways to dial back the mental clock, as well as doing good for physical health. Going out to explore could also pay dividends. Some key drivers of subjective age are attitudes towards ageing as well as relationships, community involvement and personality. In all cases,…

CLAIMS of being on the brink of slowing or even reversing ageing have a long and undistinguished history. The past is littered with the corpses of charlatans and fantasists who claimed ageing would be cured in their lifetimes. But there are now good reasons to believe that a fountain of youth – though not eternal life – is within reach. One reason for that is advances in basic biology, including the elucidation of the “hallmarks of ageing” we met in Chapter 1. One of the criteria for inclusion as a hallmark is that it must be tractable to intervention to slow it down, stop it altogether or even reverse it. All of the hallmarks have passed that test, mostly in mice and rats. But some human trials have also been…

THERE is growing evidence that our gut microbiome – the complex assemblage of bacteria, viruses, fungi and archaea residing in our intestines – can influence the ageing process, and that we may be able to manipulate it to live longer, healthier lives. The gut microbiome contains many different groups of organisms, and it changes as we age. A baby’s is dominated by bacteria that consume milk sugars, especially Lactobacillus and Bifidobacterium. Other bacteria start to move in after weaning. Two groups are especially prevalent: Firmicutes, which feast on dietary fibre, and Bacteroidetes, which consume sugar and fat. Microbial diversity appears to be a key factor in longevity and healthy ageing. A recent study of 9000 adults found that people’s gut microbiota tend to become increasingly diverse and unique with age.…

TELOMERES are segments of DNA at the ends of each chromosome, the DNA molecules that carry your genetic code. Telomeres become shorter every time a cell divides. If this shortening happens slowly, it suggests that your body is wearing well. If, say, you are a 60-year-old with telomeres as long as those of an average 50-year-old, your mortality risk is said to be equivalent to that of someone 10 years younger. Increasing numbers of people want this information, and many companies offer tests, together with various pills claimed to lengthen your telomeres and, in turn, your lifespan. If only it were that simple. We are now discovering that telomeres are an unreliable ageing clock. The links between telomere length and lifestyle choices also aren’t as straightforward as we once thought.…

THE various forms of age-related dementia – Alzheimer’s disease, vascular dementia, dementia with Lewy bodies, Parkinson’s disease dementia, frontotemporal dementia and a number of others – are arguably the most feared diseases of old age. There are around 10 million new diagnoses globally each year and around 2 million deaths, often following a progressive and devastating loss of normal cognitive function. Alzheimer’s is the most common of the dementias, accounting for about two-thirds of new diagnoses. Drugs are available, but they only slightly retard memory loss and confusion without doing anything to slow the condition’s progress. On that front there has been some advance, but also frustration and controversy. In June 2021, a new treatment for Alzheimer’s was approved by the US Food and Drug Administration, the first in nearly…

RECENT scientific findings have shown just how important middle age is, and how crucial it has been to the success of our species. Middle age – usually defined as the period from 45 to 65 years of age – is not just about getting over the hill. It is an ancient, pivotal episode in the human lifespan, preprogrammed into us by natural selection – an exceptional characteristic of an exceptional species. Compared with other animals, humans have a very unusual life history. We take a long time to grow up, we are long-lived, and most of us stop reproducing halfway through our lifespan. A few other species have some elements of this, but only humans have distorted the course of their lives in such a dramatic way. An important clue…

THE average age that menopause occurs is 51, although symptoms can start several years before that. The age at onset is quite variable, so the age your mother went through menopause can provide a clue. Around 1 per cent of people who go through the menopause experience it prematurely, before the age of 40. The menopause itself is defined as beginning at the date of someone’s final period, and is diagnosed a year after that happens. Symptoms can start three or four years beforehand, and can include hot flushes, night sweats, sleep loss, weight gain, mood swings, anxiety, problems with thought processing and forgetfulness. For many of those entering “perimenopause”, as it is known, the first hint is erratic periods. The duration of symptoms is also hugely variable. Some may…

HORMONE replacement therapies come in all shapes and sizes. They feature various mixtures of the hormones oestrogen, progesterone and testosterone and can be delivered via pills, patches, gels and implants. HRT has had a bad rap recently, as some forms have been linked to an increased risk of disease. But the risks don’t apply to everyone, and doctors now recommend “appropriate” treatment on a case-by-case basis. The first HRT was approved by the US Food and Drug Administration more than 80 years ago. Premarin, made from oestrogens extracted from the urine of pregnant horses, was licensed in the early 1940s for the treatment of hot flushes and night sweats, the most common menopausal symptoms. Yet HRT has been controversial since the 1980s, when taking extra oestrogen alone was shown to…

RESEARCH identifies six steps designed to increase lifespan by promoting lean body mass and healthy blood sugar levels, switching off the body’s central pro-ageing system and ramping up an anti-ageing process called autophagy: 1 Limit calorie intake to maintain a body mass index of 22 to 23 for men and 21 to 22 for women. 2 Eat a diet high in wholegrains, legumes and nuts. Stop eating meat to restrict intake of the amino acid methionine, but include some fish. 3 Aim to get between 45 and 60 per cent of calories from non-refined complex carbohydrates, 10 to 15 per cent from plantbased proteins and 25 to 35 per cent from plant-based fats. 4 Do a limited daily fast, eating no calories from around 3 hours before bedtime and for…

HOW healthily we age depends on many interconnected factors, including genetics, environment, lifestyle and medical history. Much of this is out of our hands. But a growing realisation that the microbes in our gut also play a part gives us some control. Here are a few simple ways you can cultivate a more youthful gut microbiota. The simplest way is to eat plenty of pulses and vegetables, especially ones high in fibre, such as artichokes, asparagus, lentils and onions. Fibre feeds your beneficial microbes. In return, they produce a range of products, including some known as shortchain fatty acids that nourish and heal the gut lining, preventing microbes from escaping into the body and damaging tissues. According to dietician Megan Rossi, at King’s College London and founder of the Gut…

SENESCENT cells are a leading cause of age-related disease. These cells have suffered some sort of irreversible damage and entered a state called senescence where they hit the emergency stop, hunker down and await destruction. Tellingly, if you take senescent cells from an old mouse and transplant them into a young one, it ages prematurely and acquires the diseases of old age. And if you remove senescent cells from old mice, they rejuvenate. For this reason, Lynne Cox at the University of Oxford sees senescent cells as “the most interesting therapeutic target” in the anti-ageing portfolio. ← Turn back to page 14 for more detail on senescence No surprise, then, that researchers have been eyeing senescent cells for many years as a juicy target. Now, we have numerous drugs in…

IT SOUNDS like something from a sciencefiction horror movie, but in the 1970s, biologists began experimenting with a gruesome procedure called parabiosis, where circulatory systems of two animals are stitched together, sometimes for weeks on end, so they share blood. Parabiosis was developed to help in the study of conjoined twins, but it also hinted at some intriguing effects on longevity. Old mice joined to young ones were rejuvenated, while the young mice aged prematurely. More recent experiments carried out at Stanford University in California confirmed the effect. “They found incredible things,” says Mark Allen, CEO of a company called Elevian. “Old animals exposed to young blood had, by many measures, a reversal of biological ageing in the heart, brain, lungs, bone, many organs. The opposite happened in young animals.”…

ONE of the hallmarks of ageing is mitochondrial dysfunction, where the power packs inside cells find it harder to produce sufficient energy, and start pumping out unwanted waste products that slowly poison our cells. This is a big problem in the brain, and may underlie many of the most devastating conditions, including Alzheimer’s, Parkinson’s, Huntington’s and motor neuron disease. These are already an enormous health burden and, as the world’s population ages, the problem is becoming ever more serious. According to this “grand unified theory” of neurodegeneration, we could prolong our brain’s healthy functioning through restoration of its mitochondria. The idea is already inspiring some exciting new therapies for age-related brain conditions, with multiple drug candidates under investigation. Some researchers are even exploring the possibility of transplanting healthy mitochondria into…

WHAT DRIVES THE AGEING PROCESS? WHAT CAN SCIENCE TELL US ABOUT THE STAGES OF LIFE? AND HOW CAN WE USE THE LATEST RESEARCH TO LIVE HEALTHILY INTO OLD AGE? AGEING IS ACCEPTED AS AN INEVITABLE FACT OF THE HUMAN CONDITION, BUT THE FORCES BEHIND IT ARE RICH AND FASCINATING. BEGIN TO UNDERSTAND THOSE AND WE CAN UNLOCK THE SECRETS TO AGEING BETTER – AS THIS 18TH NEW SCIENTIST ESSENTIAL GUIDE REVEALS. TOPICS INCLUDE: ❶ The causes of ageing ❷ Ageing in the body and mind ❸ Middle age ❹ Slowing down the clock ❺ The future of ageing…