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Researchers have identified two brain receptors that help the brain clear away amyloid beta, a hallmark of Alzheimer’s disease. By stimulating these receptors in mice, scientists increased levels of a natural amyloid-breaking enzyme, reduced buildup in the brain, and improved memory-related behavior. Because these receptors are common drug targets, the findings could open the door to affordable pill-based treatments with fewer side effects.

A new light-based sensor can spot incredibly tiny amounts of cancer biomarkers in blood, raising the possibility of earlier and simpler cancer detection. The technology merges DNA nanotechnology, CRISPR, and quantum dots to generate a clear signal from just a few molecules. In lung cancer tests, it worked even in real patient serum samples. Researchers hope it could eventually power portable blood tests for cancer and other diseases.

Getty Images Somewhere along the way to adulthood, time to play fades away. We tend to trade silliness and imagination for seriousness and busyness. Yet there is clear evidence that adults benefit from playfulness just as children do. Research shows that adults who engage in playful activities tend to cope better with stress, experience more positive emotions, show greater resilience when facing challenges, and report higher levels of life satisfaction. Our research with New Zealand families highlights how supporting unstructured play can help adults feel less stressed and more connected, while also normalising playfulness in everyday family life. In a world that demands constant busyness, play offers essential qualities we are at risk of losing: spontaneity, togetherness and the freedom to have fun. Play in adulthood can look different from play in childhood. It is less about toys or games and more about how we approach everyday experiences. Adult play can be physical, social, creative or imaginative. It might involve movement, music, humour, storytelling, problem-solving or simply doing something for the pleasure of it. What makes an activity playful is not its form, but the mindset behind it: curiosity, openness and a willingness to engage without a fixed outcome. For adults, play is often woven into hobbies and moments of exploration that sit outside work and obligation. The benefits of play in adult life A recent study suggests a potential neurobiological pathway between playfulness and cognitive health in older adults. At its core, play provides a space to reset, allowing us to step outside pressure and performance. In doing so, it supports not only stress regulation, but sustains emotional balance and quality of life across adulthood. The value of playfulness also goes beyond the individual. Playful engagement in social contexts helps build shared emotional resources, shaping how people interact and cope together over time. Playfulness in adults is also associated with higher emotional intelligence, including stronger ability to perceive and manage emotions in social situations. Observational studies further show that adults who engage playfully are more empathetic, reciprocal and positive in their interactions with others, reinforcing social connection and belonging. Importantly, play has a unique ability to cut across age boundaries. When adults and children play together, even if unrelated, differences in age, role and status tend to fade, replaced by shared enjoyment and interaction. Research suggests these inter-generational play experiences can strengthen relationships, support wellbeing and reduce age-based stereotypes. Play becomes a shared language, bridging age divides that are often reinforced by modern living. As our work highlights, unstructured play remains both possible and meaningful in contemporary life, with families reporting benefits for children’s development as well as family cohesion and shared wellbeing. These findings suggest play can function as an ordinary, rather than exceptional, feature of family and community life. Making room for play in everyday life If play matters across the lifespan, the spaces we inhabit need to support it. Yet most public environments continue to treat play as something designed primarily for children. Research in urban design suggests the most effective playful environments for adults are those that don’t announce themselves as playgrounds, but instead embed playful possibilities into everyday settings. Features such as oversized steps, stepping stones, interactive seating or winding paths can invite exploration, balance and movement. In some cities, this extends to adult-sized play elements integrated into public space, such as musical swings that turn routine movement into playful interaction. Despite these examples, play-oriented design remains the exception rather than the norm, with most public play infrastructure still concentrated in children’s spaces. Designing cities that invite adult play as part of everyday life could be a valuable investment in inclusion, social connection and population wellbeing. Environments that support play are not just physical, but social. Just as urban design can invite or discourage playful movement, social norms shape whether play feels acceptable in adult life. When play is treated as embarrassing, indulgent or something to apologise for, it quickly disappears. But when playful behaviour is visible and unremarkable, it becomes easier for others to participate. Play has long been treated as something separate from adult life, confined to childhood or reserved for rare moments of leisure. Yet the evidence suggests playfulness continues to matter well beyond early development. Reframing play as a legitimate part of adult life opens up new ways of thinking about wellbeing across the lifespan. Melody Smith has no conflicts to declare. Scott Duncan does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Researchers have built a realistic human mini spinal cord in the lab and used it to simulate traumatic injury. The model reproduced key damage seen in real spinal cord injuries, including inflammation and scar formation. After treatment with fast moving “dancing molecules,” nerve fibers began growing again and scar tissue shrank. The results suggest the therapy could eventually help repair spinal cord damage.

For the first time, researchers have shown that self-assembled phosphorus chains can host genuinely one-dimensional electron behavior. Using advanced imaging and spectroscopy techniques, they separated the signals from chains aligned in different directions to reveal their true nature. The findings suggest that squeezing the chains closer together could trigger a dramatic shift from semiconductor to metal. That means simply adjusting density could unlock entirely new electronic states.

Researchers have uncovered the enzyme behind chromothripsis, a chaotic chromosome-shattering event seen in about one in four cancers. The enzyme, N4BP2, breaks apart DNA trapped in tiny cellular structures, unleashing a burst of genetic changes that can help tumors rapidly adapt and resist therapy. Blocking the enzyme dramatically reduced this genomic destruction in cancer cells.

A dazzling new Hubble image peels back the layers of the mysterious Egg Nebula, a rare and fleeting phase in a Sun-like star’s death just 1,000 light-years away. Hidden inside a dense cocoon of dust, the dying star blasts twin beams of light through a polar opening, carving glowing lobes and delicate ripples into the surrounding cloud. These striking, symmetrical arcs hint that unseen companion stars may be shaping the spectacle from within.

Scroll through social media and you’ll quickly encounter phrases like “I am worthy” or “I choose happiness”. The tantalising promise is: repeat these positive affirmations often enough and you’ll be happier, calmer and even healthier. Given we are biologically hardwired to avoid suffering and want to feel safe and happy, no wonder it is tempting. But is it backed by science? And are there downsides? What are positive affirmations? Self-affirmation theory was proposed by psychologist Claude Steele in the late 1980s and remains popular today. The theory suggests we have a deep desire to craft a personal narrative that we are “adequate” and “worthy”. But painful experiences that trigger shame or embarrassment – such as getting bad grades, making a mistake at work or going through a break-up – can threaten this self-narrative. You may become more self-critical, and this may make you more likely to experience anxiety, depression and even self-harm. In contrast, self-affirmation theory suggests repeating positive ideas about yourself can protect you from these negative mental health symptoms, boosting your mood and sense of self-worth. Is there evidence positive affirmations work? Yes – in some contexts. A review from 2025 combined and analysed results from 67 studies. These looked at the effects on participants’ wellbeing of writing positive affirmations or repeating them out loud. The review found positive affirmations did have a meaningful impact on how participants viewed themselves and connected with others. But the effect was small. Some studies have found repeating positive affirmations can protect social media users’ self-esteem and boost the overall mental health of university students. One 2025 study looked at women undergoing chemotherapy for breast cancer. It found those who listened to music alongside recordings of positive affirmations felt less depressed and drowsy, compared to those who listened only to music. Another study from 2025 examined adults with depression symptoms, but no diagnosis. It found those who wrote personal positive affirmations twice daily reported better self-esteem after 15 days, compared to those who didn’t. One frequently cited study from 2009 found repeating positive affirmations (for example, “I am a lovable person”) boosted mood. However this was only for people who already had high self-esteem. Those with low self-esteem – in other words, those with a low level of confidence and value in themselves – reported poorer mood. While these studies show some promise, recent studies have failed to replicate these findings. More research is needed to see exactly who might benefit, and in what context. The downsides of positivity But is there any harm in using positive affirmations? Here are some risks to keep in mind. Toxic positivity Humans are imperfect and the world is often unfair. Pretending otherwise can lead to toxic positivity, which means suppressing or even denying difficult feelings. When you feel distressed, you may feel pressure to cope and simply “reframe” your thinking. You may feel ashamed when you can’t and be less likely to seek help. Chasing dopamine Repeating positive affirmations might give you a quick dopamine hit. Dopamine is the hormone linked to pleasure and reward, and can help us feel in control and competent. But the desire to always feel good is not realistic. And taken to the extreme, it can trap you in a cycle where you’re constantly seeking the next dopamine hit. Downplaying real issues Positive self-talk is only helpful in safe environments. In unsafe or harmful situations (for example, an abusive relationship) staying positive may blind you to potential dangers. Over-reliance on positive affirmations can detach you from what’s going on, and override gut instincts it may be better to listen to. Being overly positive may be a danger in unsafe relationships or environments. Simran Sood/Unsplash So, what does work? Recent research suggests how we talk to ourselves may matter more than how positive the message is. Here are two approaches worth trying. Show yourself compassion Research shows cultivating a compassionate relationship with yourself, especially during stress or failure, can strengthen your resilience and improve your mental health. For example, telling yourself “this is hard” or “anyone would feel this way” can be more helpful than simply repeating upbeat affirmations. Sometimes being brave enough to acknowledge you’re suffering, and speaking to yourself like a good friend, is what you need. Create some distance Talking to yourself in the third person – for example, “Maddie is furious, but has handled far worse” rather than “I am furious” – can help. This creates distance between you and your thoughts, and is sometimes called “non-attachment”. This approach can help regulate emotions, encouraging us to approach feelings with curiosity, observing rather than just reacting to them. The bottom line Very few thinking styles are always beneficial or always harmful. The key is to be flexible, not rigid. This means regularly asking yourself “is that thought helpful?” and choosing the approach most suited to your situation. And if that’s positive self-talk, try to use compassion and understanding – not just upbeat slogans. Madeleine Fraser does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

joyce huis/Unsplash When we talk about a biological clock ticking, it usually means the pressure women feel to fall pregnant before a certain age. It’s linked to the decline in eggs (ova) and fertility as females age. But sperm numbers and fertility similarly decline with age in men. When a heterosexual couple experiences fertility issues, it’s equally likely due to male and female factors. Yet the woman is usually tested first. But this is changing. New male infertility guidelines for Australian GPs recommend the male and female partner undergo investigations at the same time. A growing body of research highlights the role of men in infertility and how a man’s age and health matters when trying to conceive. Let’s look at the evidence. Semen and sperm health decline with age Sperm are produced in the testes continuously from puberty, but sperm count (the average number of sperm in an ejaculate) starts to decline when a man is in his early twenties. Men over 55 have average sperm counts close to or below the threshold for infertility. But it’s not just the number of sperm that matters. Sperm need to be alive, have good motility (movement or “swimming ability”) and be the correct shape to reach and fertilise an egg in the female reproductive tract. An adequate volume of semen (sperm and seminal fluid together) is also necessary because this provides nourishment to sperm. What’s the difference between sperm and semen? And can pre-ejaculate get you pregnant? From around age 30, the number of sperm with good motility and correct shape, and semen volume decline, while the number of dead sperm increases. The biggest changes generally occur from around 35 years of age. The age-dependent decline in sperm and semen affects male fertility. In studies of more than 2,000 couples, one study showed men older than 45 took five times longer to conceive than men younger than 25. Another study found the chance of falling pregnant within a year was 20% lower at 45 compared to the peak at 30. Genetic damage and miscarriage risk increase with age Though a sperm might have reached and fertilised an egg, if it contains genetic damage, this can also affect fertility or the baby. As men age, their sperm accumulate more genetic damage, including damage to DNA and chromosomes (coils of DNA that carry genes). This is because sperm stem cells replicate hundreds of times during their life. Each time a cell replicates, there is a risk of genetic damage. Genetic damage to sperm can stop the embryo developing and result in miscarriage. This is linked to about 30% higher chance of miscarriage in men older than 40 compared to those aged 25–29. New techniques have shown chromosomal abnormalities in sperm also increase with age. These can cause birth defects and chromosomal syndromes such as Down syndrome and Klinefelter syndrome. Beyond ageing and sperm’s biological clock Several environmental and lifestyle factors also affect semen and sperm measures, and therefore fertility. Oxidative stress (too many damaging chemicals and not enough antioxidants) disrupts sperm production and increases sperm DNA damage, and is strongly linked to male infertility. Oxidative stress is increased by environmental toxins such as pollution, heavy metals, pesticides and some chemicals. Oxidative stress also increases with certain lifestyle factors, including smoking, alcohol, illicit drugs, too much processed meat and sugar consumption, obesity and being sedentary. Male infertility can also be due to medical causes such as erectile dysfunction, or issues with the male reproductive tract or blood vessels. A varicocele (dilation of the veins that drain the testes) is one of the most common causes of male infertility, and treatable. One or two in 100 men with infertility will not have the tubes that transport sperm from the testes to the penis, which means their semen does not contain sperm. However, for about one in three cases of male infertility, the cause is not known. The new guidelines The World Health Organization recognises the importance of addressing infertility in everyone, regardless of sex or gender. Australia’s first male infertility guidelines support this by recommending infertility is investigated in both partners in heterosexual couples. For the male, this includes examination of the penis, scrotum and testes, and semen and blood analyses. For the one in nine couples in Australia with fertility problems, this will help them find answers and treatment options sooner. Staying healthy for fertility If you’re looking to conceive, age is a consideration but not the only factor. For optimal sperm health, you can focus on: eating a healthy diet with enough vitamins A, C, E and D not smoking reducing alcohol maintaining a healthy weight exercising avoiding chronic stress avoiding excessive exposure to environmental toxins and pollutants. Reducing unnecessary stress or pressure around falling pregnant is also important. In Australia, most pregnancies are normal and most babies are healthy, regardless of the age of the parents. Women are often told their fertility ‘falls off a cliff’ at 35, but is that right? Theresa Larkin does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

Organic Media/Getty Depression and anxiety affect millions of people worldwide. While treatments such as medication and psychotherapy (sometimes called talk therapy) can be very effective, they’re not always an option. Barriers include cost, stigma, long waiting lists for appointments, and potential drug side effects. So what about exercise? Our new research, published today, confirms physical activity can be just as effective for some people as therapy or medication. This is especially true when it’s social and guided by a professional, such as a gym class or running club. Let’s take a look at the evidence. What we already knew Physical activity has long been promoted as a treatment option for anxiety and depression, largely because it helps release “feel good” chemicals in the brain which help boost mood and reduce stress. But the evidence can be confusing. Hundreds of studies with diverse results make it unclear how much exercise is beneficial, what type, and who it helps most. Over the past two decades, researchers have conducted dozens of separate meta-analyses (studies that combine results from multiple trials) examining exercise for depression and anxiety. But these have still left gaps in understanding how effective exercise is for different age groups and whether the type of exercise matters. Many studies have also included participants with confounding factors (influences that can distort research findings) such as other chronic diseases, for example, diabetes or arthritis. This means it can be hard to apply the findings more broadly. What we did Our research aimed to resolve this confusion by conducting a “meta-meta-analysis”. This means we systematically reviewed the results of all the existing meta-analyses – there were 81 – to determine what the evidence really shows. Together, this meant data from nearly 80,000 participants across more than 1,000 original trials. We examined multiple factors that might explain why their results varied. These included differences in: who they studied (for example, people with diagnosed depression or anxiety versus those just experiencing symptoms, different age groups, and women during pregnancy and after birth) what the exercise involved (for example, comparing aerobic fitness to resistance training and mind-body exercises, such as yoga; whether it was supervised by a professional; intensity and duration) whether the exercise was individual or in a group. We also used advanced statistical techniques to accurately isolate and estimate the exact impact of exercise, separate from confounding factors (including other chronic diseases). Our data looked at the impact of exercise alone on depression and anxiety. But sometimes people will also use antidepressants and/or therapy – so further research would be needed to explore the effect of these when combined. What did the study find? Exercise is effective at reducing both depression and anxiety. But there is some nuance. We found exercising had a high impact on depression symptoms, and a medium impact on anxiety, compared to staying inactive. The benefits were comparable to, and in some cases better than, more widely prescribed mental health treatments, including therapy and antidepressants. Importantly, we discovered who exercise helped most. Two groups showed the most improvement: adults aged 18 to 30 and women who had recently given birth. Many women experience barriers to exercising after giving birth, including lack of time, confidence or access to appropriate and affordable activities. Our findings suggest making it more accessible could be an important strategy to address new mothers’ mental health in this vulnerable time. How you exercise matters We also found aerobic activities – such as walking, running, cycling or swimming – were best at reducing both depression and anxiety symptoms. However, all forms of exercise reduced symptoms, including resistance training (such as lifting weights) and mind-body practices (such as yoga). For depression, there were greater improvements when people exercised with others and were guided by a professional, such as a group fitness class. Unfortunately, there wasn’t available data on group or supervised exercise for anxiety, so we would need more research to find out if the impact is similar. Exercising once or twice a week had a similar effect on depression as exercising more frequently. And there didn’t seem to be a significant difference between exercising vigorously or at a low intensity – all were beneficial. But for anxiety, the best improvements in anxiety symptoms were when exercise was done: consistently, for up to eight weeks, and at a lower intensity, such as walking or swimming laps at a gentle pace. So, what does all this mean? Our research shows exercise is a legitimate and evidence-based treatment option for depression and anxiety, particularly for people with diagnosed conditions. However, simply telling patients to “exercise more” is unlikely to be effective. The evidence shows structured, supervised exercise with a social component is best for improving depression and anxiety. The social aspect and the accountability may help keep people motivated. Clinicians should keep this in mind, offering referrals to specific programs – such as aerobic fitness classes or supervised walking and running programs – rather than general advice. The findings also suggest this kind of exercise can be particularly effective when targeted to depression in younger adults and women who’ve recently given birth. The takeaway For people who are hesitant about medication, or facing long waits for therapy, supervised group exercise may be an effective alternative. It’s evidence-based, and you can start any time. But it’s still best to get advice from a professional. If you have anxiety or depression symptoms, you should talk to your GP or psychologist. They can advise where exercise fits in your treatment plan, potentially alongside therapy and/or medication. Samantha Teague receives funding from the National Health and Medical Research Council (NHMRC). James Dimmock, Klaire Somoray, and Neil Munro do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.

Up to four in ten cancer cases worldwide could be prevented, according to a new global analysis from the World Health Organization (WHO) and its International Agency for Research on Cancer (IARC). The study examines 30 preventable causes, including tobacco, alcohol, high body mass index, physical inactivity, air pollution, ultraviolet radiation – and for the first time – nine cancer-causing infections.

Progress made during the six years, since the declaration of COVID-19 as a Public Health Emergency of International Concern, in preparing for a future pandemic, and what remains to be done.

New analysis from a WHO global expert committee on vaccine safety has found that, based on available evidence, no causal link exists between vaccines and autism spectrum disorders (ASD). The conclusion reaffirms WHO’s position that childhood vaccines do not cause autism.

This year’s report provides a critical and up-to-date snapshot of efforts to control and eliminate malaria across 80 countries. The report also presents the threat posed by antimalarial resistance and its impact.