Innholdsfortegnelse for EG03 i New Scientist - The Essential Guides

THE coronavirus pandemic has reminded us how much we tend to take our health, both physical and mental, for granted. Yet good health isn’t simply the absence of disease. It is a state in which we can adapt to, and cope with, whatever life throws at us – even if we have a chronic disease or disability. This Essential Guide is a newly re-edited and updated collection of material originally published in New Scientist magazine, addressing some of the latest thinking on what underlies good physical and mental health: the origins of many common diseases; strategies for tackling them; and how to minimise our chances of falling ill in the first place. Human health is a huge topic, and what is contained in this Essential Guide cannot be exhaustive. Nor…

HUMAN body temperature is generally thought of as 37°C, although anything between 36.5°C and 37.5°C is generally considered normal. However, once your temperature hits 38°C, you have officially got a fever. If body temperature rises too far, it can be fatal. Our cells begin to die, releasing proteins into the blood that can damage the kidneys and other organs, resulting in their failure. The exact temperature this happens at probably depends on the source of a person’s fever, as well as other factors such as how hydrated they are. “The number 40 [degrees] scares a lot of doctors,” says Mark Peters at the UCL Great Ormond Street Institute of Child Health in London. So, if fever can kill us, why does it happen? Fever-like responses are observed in many organisms,…

STRESS is an essential physiological response that allows us to quickly adapt to the world around us. It begins in a region of the brain called the amygdala, which is on constant surveillance for any potential threat. The amygdala combines sensory information with memories of similar situations to judge whether an emergency response is required. If alarm bells ring, a distress signal is sent to the hypothalamus – a small nodule near the base of the brain – which activates two major pathways. The first triggers our ancient fight-or-flight system, which pumps out adrenaline, making us more alert by increasing our heartbeat and the efficiency of our breathing and forcing more blood into our muscles. The second prompts the release of other hormones, including cortisol. This keeps the stress response…

Sadly, the answer is probably yes. This is in part down to basic biology: some people simply have an immune system that is more allergy-prone – probably due to a combination of genetics plus environmental exposure. Not only that, immune cells sensitised to one allergen can cross-react with other related proteins, meaning allergies can “spread”. For instance, some of the proteins in birch pollen are closely related to those in alder and hazel, which peak around a month earlier, potentially prolonging the agony for someone sensitised to birch. Foreign travel is another thing that can foster the development of new allergies. If you travel to southern Spain in spring and there is a lot of olive pollen then you could become sensitised to it. And because olive pollen cross-reacts with…

Advances in modern medicine during the past century have led to a remarkable improvement in life expectancy, largely thanks to our successful conquering of many infectious diseases. Yet as increasing numbers of us survive well into old age, chronic, non-communicable diseases like heart disease, type 2 diabetes and dementia are becoming more commonplace. Although ageing is a risk factor for these conditions, they are not inevitable. Neither do we, biologically, age at the same rate. But the more we learn about these seemingly very different age-related diseases, the more similar their underpinning causes seem to be. Intriguingly, so too are the measures we can take to reduce our risks.…

1. Lose excess weight Fat is a storehouse of inflammatory cytokines 2. Eat your omega-3s The body uses them to make resolvins, which help switch off inflammation 3. Exercise Being active releases anti-inflammatory chemicals and tells the liver to metabolise fat 4. Stretch Extending inflamed muscles seems to soothe them in rats 5. Take low-dose aspirin The only currently available drug that stimulates cessation of inflammation (check with your doctor first)…

THROUGHOUT evolution, humans have been active. Our ancestors chased prey as hunter-gatherers and fled from predators. More recently, they laboured on farms and in factories. But the decline of agricultural and industrial labour, plus the invention of the car, a multitude of labour-saving devices and – most perniciously – TV, computers and video games, mean we’ve all ground to a sudden and catastrophic standstill. Now we are paying the price. In 2009 Steven Blair, an exercise researcher at the University of South Carolina in Columbia, published a study of more than 50,000 men and women showing that a lack of cardiorespiratory fitness was the most important risk factor for early death. It accounted for about 16 per cent of all deaths in men and women over the period of study,…

MORE than a century ago, British psychologist Charles Spearman noted that children’s performance on one kind of mental task, say verbal fluency, was correlated with their mental skill in other areas, such as mathematical reasoning, spatial manipulation and logic. In other words, children who are good at one thing tend to be good at another, while those who struggle in one area tend to struggle in others. Using a statistical tool called factor analysis, Spearman showed that this is because these different mental abilities are all linked to an overarching cognitive capacity, which he named general intelligence, or the g factor. Today, applying the same approach to mental health diagnoses has provided the first hints that something similar might be going on. There are a wide range of mental health…

In 2016, researchers discovered that the sticky amyloid plaques whose buildup is associated with Alzheimer’s disease (see next article) seem to function as a sticky defence against bacteria. They found that the protein can act as an anti-microbial compound that kills bacteria. When they injected bacteria into the brains of mice engineered to make Alzheimer’s proteins, plaques developed round bacterial cells overnight. At the time, the team said it still believed that amyloid itself went on to cause the brain damage of Alzheimer’s, not bacteria. But a spate of subsequent studies have looked at microbes, and suggested an alternative hypothesis. Bacteria have been found in the brains of people who had Alzheimer’s when they were alive. But it hasn’t been clear whether the bacteria caused the disease or were simply…

CANCER affects every one of us. Whether or not you have had it yourself, you surely know someone who has. For people in the UK, the lifetime chance of being diagnosed with the disease is 1 in 2. Globally, cancer is second only to cardiovascular disease as a cause of death, killing an estimated 1 in 6 people. We are bombarded with so much information and misinformation about what might cause cancer that it is often hard to separate myth from reality. The extent of public confusion on the subject was glaringly exposed in a survey of 1330 people in England published last year. Researchers from University College London and the University of Leeds, UK, reported that more than a third of the general public mistakenly attributed carcinogenic properties to…

George Church made his name as a pioneer of gene sequencing in the 90s. Since then, he has powered advances in gene editing, including being among the first to apply CRISPR technology to human cells. A professor of genetics at Harvard Medical School and a prolific entrepreneur, Church’s latest ventures include trying to persuade many more people to get their genomes sequenced and exploring ways of reversing ageing in dogs. Here, he provides a glimpse of what future medicine could look like. How exactly does the gene-editing technology CRISPR work? Gene editing involves snipping out a targeted DNA sequence and replacing it with another. It used to be time-consuming and imprecise, but now you can edit any living genome, using your computer to target a stretch of DNA. Guides made…

FROM a biological point of view, ageing is essentially the progressive loss of the body’s ability to repair itself. As our repair processes fail, damage proliferates. Organs and tissues clog up with clumps of protein and other detritus. Genetic mutations accumulate. Chromosomes start to unravel. Some cells become cancerous, others turn into zombies. Immune defences weaken. The powerhouses of our cells, mitochondria, fall into disrepair. Low-level inflammation, called inflammaging, creeps through the body. Thank science, then, that we now know enough about those repair processes to try rebooting them with drugs. A lot of the smart money is on a class of drugs called senolytics, which seek out and destroy the worn-out cells that build up as we age. These cells have suffered some sort of irreversible damage and entered…

Ever since I learned that people eventually died, I have had this fear of death churning away in the background. As a child I was always thinking “isn’t there something we can do about this?” I considered cryopreservation for many years and then signed up as a neuro – which means I’ll only have my head preserved – in 2007. It made perfect sense to me that the mind arises as an emergent property of the brain and that it might be possible to preserve that. I don’t know whether it will be possible to bring someone back because it’s hard to know what kind of repair work you would have to do to correct any deterioration. Is it a case of engineering viruses or blood cells that are available…

Even if we didn’t know it before, the coronavirus pandemic has made it plain: the immune system holds the key to human health. More powerful than any drug, every minute of every day it is hard at work defending us from invasion by foreign organism – not just viruses, but bacteria, fungi, and parasites. When the immune system is working well, we barely notice it, but when it fails, sometimes fatal infectious and autoimmune diseases result. So how does this powerful defence system work, and why does it sometimes turn against us?…

IN THE latter part of the 19th century, mounting evidence that germs cause disease kicked off more than a century of war against them. We expunged them from our water, food and homes with disinfectants, roused our immune systems against them with vaccines and wiped out bacteria with penicillin and other chemical weapons. Human deaths caused by infectious diseases fell by more than 90 per cent, contributing to a broader transformation of society. If nothing else, the arrival of coronavirus is a reminder of the extent to which we have rid ourselves of infectious disease and the plagues which have long been a feature of human history. This freedom has come at a cost. Taking a dose of antibiotics is like throwing a stink bomb into a subway. The criminals…

We all produce a chemical called neuropeptide Y (NPY) that acts like an on-off switch to modulate our body’s stress response. Intriguingly, a single injection of NPY before a stressful experience seems to protect animals from some of the negative consequences of stress. This discovery inspired James Murrough and Dennis Charney at Mount Sinai Hospital in New York to try a similar approach for people with post-traumatic stress disorder (PTSD). Each volunteer was given an intranasal dose of NPY before reading a story designed to trigger their PTSD. Although only a small pilot study, it hinted that NPY might offer relief from some PTSD symptoms. There was a problem though: it took an hour of inhalation and a specially designed gadget to get enough of the chemical into people’s brains.…

AGEING results from a progressive accumulation of cellular damage over time, resulting in a deterioration in our fertility, physical and mental capacity, an increased risk of disease, and ultimately, death. Yet these changes are only loosely associated with someone’s chronological age. The most widely cited theory of ageing is that telomeres, genetic caps on the ends of chromosomes, grow shorter each time a cell divides, like a wick burning on a candle. Once these are used up, the cell withers and dies. But a new idea gaining ground suggests ageing is instead a byproduct of how energy intensive it is for our bodies to continuously repair faults that occur in our DNA as cells divide. From an evolutionary perspective, there is little reason to maintain that process for ever, after…

ANXIETY disorders – generalised anxiety, panic attacks, social anxiety and phobias – are the most prevalent mental health problem in the US and Europe. A growing number of reports suggest they could be a global concern. In the West, they cost healthcare systems more than $40 billion each year. On average 1 in 6 of us will contend with an anxiety disorder at some stage in our lives. The damage is real. Anxiety disorders have been linked to depression and increased substance abuse, particularly of alcohol. A recent study found that men who have anxiety disorders are twice as likely to die from cancer as men who don’t, even when factors such as drinking and smoking are taken into account. Unlike stress, which normally occurs within a discrete time frame,…

I DON’T mean to pry, but how much sleep did you get last night? What about over the past week? I ask because the answer could have serious consequences for your future mental health. More than 44 million people worldwide currently have Alzheimer’s disease, including members of my own family. The health, economic and personal impact is staggering. There has been a marked acceleration in the number being diagnosed with the disease as the human lifespan has increased, but also, importantly, as total sleep time has decreased. As a sleep scientist, I became interested in this connection some years ago. What I have found is striking. Not only does sleep disruption play a role in the declining mental abilities that typify Alzheimer’s disease, but getting enough sleep is one of…

WASH your hands religiously for 20 seconds, avoid touching your face, ensure all poultry is thoroughly cooked, practice safe sex, and, as a last resort, shut yourself away with only your emergency rations for company. The coronavirus pandemic has reminded us of the importance of some of these sensible procedures for avoiding the effects of an infectious agent. But the most important thing standing between you and a possibly deadly disease, whether covid-19, winter flu, salmonella poisoning or HIV/AIDS, is your immune system. The body has two key lines of defence against foreign invaders: the innate and adaptive immune systems. Innate immunity is the first line of defence, staffed by general-purpose, pathogen-killing cells such as neutrophils and macrophages. The job of these early responders is to try and hold off…

Antibiotics are widely regarded as some of the safest drugs going. Indeed, until recently many doctors prescribed them for viral infections – despite knowing they were useless – on the grounds that “it can’t hurt”. Except that it can. And not just because it leads bacteria to develop resistance to the drugs. Antibiotic-associated diarrhoea and allergic reactions commonly send people to hospital. And antibiotic use is almost always the cause of diarrhoea associated with Clostridium difficile, which kills nearly 30,000 Americans every year. People who study the microbiome believe the toll may be far higher. One study in Denmark, for example, revealed that people who redeemed five or more antibiotic prescriptions over the course of a 15-year period were much more likely to develop type 2 diabetes compared with those…

Modern life seems to throw all sorts of novel health challenges at us, be it ubiquitous stress or the rise of allergies and food intolerances. But there are few things new under the sun. Stress derives from an essential evolutionary response that allows us to survive in a fast-changing world, while allergies represent just another misdirected immune response. Understanding the origins of these conditions allows us to combat them better. The answers are often the same: more exercise, better diet and a good dose of social interaction.…

CHRONIC itch is a surprisingly common problem. It can come as a side-effect of opioid painkillers, the use of which has rocketed in recent years. It is associated with skin conditions such as eczema as well as nerve damage, kidney disease and allergies. An estimated one in five of us will experience chronic itch, defined as itchiness lasting for six weeks or more, at some point, and current remedies are providing little relief. The most common treatments are antihistamines, which block the part of the immune reaction that causes itching when we are bitten by a bug, for example. Not all itches are immune-related, however, and antihistamines have proven to be ineffective for most forms of chronic itch. Neuropathic itch, which stems from damage to sensory nerves in the skin,…

Mental health conditions such as depression, anxiety and schizophrenia are shockingly common, affecting perhaps 1 in 4 of us at some point in our lives. Meanwhile the rise of neurodegenerative diseases such as Alzheimer’s is itself a worrying trend in many ageing populations. Recent research gives some cause for optimism, however. The discovery that many mental health conditions may be related to one another gives new perspectives on how to tackle them. And while the problem of Alzheimer’s is far from solved, we have new clues on what we can do to combat it. In general, the mantra “a healthy mind in a healthy body” rings very true.…

Studies are cruelly consistent: by the age of 45, our basic cognitive abilities begin to slip, and as we get older, the crucial brain regions involved in memory, attention and perception shrink and no longer communicate with one another as efficiently as they once did. You may find that you aren’t quite as quick as you once were. It takes longer to recall where you left your keys, more effort to help your kids with their maths homework. This doesn’t necessarily mean you’ll get dementia. Getting older slows us down, but the human brain can stay sharp well past 100 years of life, and when healthy older people are given extra time to perform cognitive tasks, the results are usually on par with younger folks. Even if you do receive…

Every animal needs sleep. Rats deprived of sleep die within in a month, and people with a rare insomnia disease also die early. A wide range of disorders have been linked to disturbed sleep or sleep deprivation, but we still don’t really know what sleep is for. One theory is that sleep helps us consolidate new memories, but sleep may be important for pruning down the connections between our brain cells, to free up space for future memories. How much sleep you need is influenced by your genetics. It’s good to aim for between 7 and 9 hours every night, but some people may need 10 or be fine after only 6. While it’s tempting to flatter yourself, bear in mind that only 3 per cent of people can get…

We have made enormous progress in our understanding of disease, and in developing strategies to prevent and treat it. In the coming decades, new tools should enable us to edit our genomes and turn back the clock on our aging cells. If that fails, we may even be able to put our deteriorating bodies on ice, for some future generation to patch up. What will these new technologies mean for human health? We kick off our discussion with an interview with George Church, a prime mover in the field of gene editing.…

STEM cells are the blank slate from which the body can build any type of cell it needs. Most versatile are embryonic stem cells (ESCs), found in three to five-day embryos, which can differentiate into any tissue type. Adult stem cells, on the other hand, are found in adult bone marrow, fat, and possibly other tissues such as the heart and brain, albeit in small numbers. Compared with ESCs, these have a more limited ability to give rise to various cells of the body. For instance, bone marrow stem cells can give rise to various types of blood cell, but they cannot grow a new brain. For a long time, biologists assumed that other types of adult cells were largely stuck with their fates. Once ESCs had differentiated into skin…

CRYONICS, the cooling of humans in the hope that one day technology will be able to bring them back to life, has a reputation as a vanity project for those who have more money than sense. Yet, in the last few years, the discipline has made remarkable inroads. As well as bodies, Timeship, the new Mecca of cryogenics in Comfort, Texas, will store cells, tissues and organs, in a bid to drive forward the capabilities of cryogenics. Its cutting-edge facilities should break through the limitations of current cryopreservation, making it more likely that tissues – and whole bodies – can be successfully defrosted in the future. Timeship is the brainchild of Bill Faloon and Saul Kent, two entrepreneurs and prominent proponents of life extension research. Their vision was to create…