Mind & body, in brief

A Stanford University team led by the neuroscientist Sergiu Pasca bred mice that grow almost none of their own cerebral cortex, the outer layer of the brain used for thinking, memory and the senses. [1][2]

Into newborn mice they placed clumps of human brain-like tissue, called organoids, grown from human stem cells over about 40 days. [3][1]

Within weeks to months the human cells divided, grew blood vessels and filled most of the empty space. [4]

About half of each brain ended up human by volume, though not by number of nerve cells. [5][4]

The human nerve cells connected with the rest of the mouse brain, and some sent fibres down into the spinal cord. [1][5]

The tissue also made a kind of large nerve cell linked to social skills, which mice do not have and which is found in big-brained animals such as whales and primates. [3][5]

Mice born without a cortex did worse than normal mice on a maze memory test, and mice given the human tissue almost fully closed that gap. [3]

When oxygen was cut, the part-human mice developed problems walking, like those in cerebral palsy; ordinary mice cope with low oxygen because they evolved living underground. [3][4]

Pasca said psychiatry has one of the lowest success rates for clinical trials, and that drugs which work well in animals fail badly in patients. [2]

The human tissue is still untidy: most cell types are there, but not sorted into the neat layers of a real cortex. [3][2]

In 2025 the US NIH and FDA pledged to cut animal testing for some medicines, and the NIH announced $87 million for a new organoid centre. [6]

The paper came out in Nature on 16 September, and an editorial in the same journal called it the most extensive merging of human brain cells into an animal so far. [5][7]

Why it matters. Watch whether an international body for brain organoid research is set up, and whether anyone tries the same thing in bigger, longer-lived animals such as pigs or monkeys. [7][4]

On 30 September a US Senate health committee voted along party lines to send Nicole Saphier's nomination as surgeon general to the full Senate. [20] The surgeon general is the US government's top doctor and public health educator. [20] Saphier, a radiologist who has appeared on Fox News, is President Trump's third pick, after two earlier nominees failed to win enough support. [20] At her hearing on 16 September she said she had seen no reputable evidence that vaccines cause autism. [17]

Why it matters. No date is set for the full Senate vote. [20] Almost 3,300 US measles cases had been confirmed this year by 11 September, more than in all of 2025, which is why her answers on vaccines drew attention. [17]

Researchers at Memorial Sloan Kettering Cancer Center in New York recorded more than 40,000 food items eaten by 158 people with blood cancers during weeks in hospital on antibiotics. [21] Antibiotics kill many gut bacteria, and the variety of those bacteria matters for digestion and health. [21] For every extra 100 grams of high-sugar food, about one large milkshake, the drop in variety was on average 24% bigger. [21] The sugar also helped Enterococcus faecium, a germ behind hospital infections, to grow. [21] New Scientist reported the study on 30 September. [21]

Why it matters. It is a link seen in what patients chose to eat, not a trial that cut their sugar. [21] It matches a mouse study from the University of Louisville in which a high-sugar diet let a gut germ called C. difficile settle in and made its illness worse. [9]

WHO experts met in the week of 21 September to choose which flu strains go into vaccines for the southern hemisphere's 2027 season. [22] Flu viruses keep changing, so the vaccine is updated twice a year, once for each half of the world, using samples from WHO's worldwide network of labs. [22] New variants can appear after the choice is made, leaving the vaccine a poorer match. [23] A study of 63 past seasons found a repeatable method could have improved the match in 51 of them. [23]

Why it matters. Choosing three months later would have improved the match further in 14 of the 63 seasons, if faster vaccine methods allowed it. [23] In the US, the CDC says legal uncertainties mean its July 2025 flu vaccine advice still stands for the 2026-27 season. [18]

A review of nine studies covering 480,479 people aged 35 to 84 found that regular stair climbers had a 39% lower risk of dying from heart and blood-vessel disease. [11] Their risk of dying from any cause was 24% lower. [11] It was published on 13 August 2026 in the American Journal of Cardiovascular Drugs. [11] The studies watched what people did and assigned nobody to climb stairs, so they cannot show the stairs caused the benefit. [11]

Why it matters. A 2026 opinion paper argues that people who are already fitter are the ones who take the stairs, which would make stairs a sign of health rather than its cause. [12] It also warns that hard climbing can strain the hearts of some heart patients. [12]

Researchers followed 4,884 US men whose prostate cancer had not spread, from a long-running study of male health workers, for a median of almost 13 years. [24] Men who ate the most saturated fat after diagnosis were 24% more likely to die than those who ate the least. [25] The extra deaths were mostly from heart disease and other cancers, not from prostate cancer. [25] It appeared in JAMA Network Open on 2 September 2026. [25]

Why it matters. About 3.5 million US men live with prostate cancer, often for many years, so what kills them is often something else. [25] Swapping a tenth of calories from animal fat to plant fat went with a 16% lower risk of death, though the men chose their own food. [25]

COVID virus levels in US wastewater have risen steadily since July, most in the western and southern states, Scientific American reported on 21 September. [19] Positive tests are rising too, but hospital admissions have not followed yet. [19] Nearly half of current samples are descendants of a strain called XFG, which has led infections for more than a year, so most immune systems have met something close to it. [19]

Why it matters. This year's updated vaccines are aimed at XFG. [19] Wastewater, then positive tests, then hospital beds is the usual order, so doctors are watching for the third step. [19] Infection still causes long COVID, though nobody can yet say how often. [19]

In January 2026 the American Cancer Society, a US charity that counts the country's cancers, reported that 70% of people diagnosed between 2015 and 2021 were alive five years later, compared with people without cancer. [14] That is the highest it has recorded, up from about half in the mid-1970s. [14] Survival with myeloma, a bone-marrow cancer, rose from 32% to 62% since the 1990s, and with liver cancer from 7% to 22%. [14]

Why it matters. The society's chief scientist named less smoking first among the reasons: the share of active smokers fell from 44% to 11% since the 1960s. [26] The same report projected more than 2 million new US cases and over 625,000 deaths in 2026. [14]

In July the WHO published the first five-year breast cancer survival estimates for all 194 of its member countries, for women diagnosed from 2017 to 2021. [15] The global middle figure was 77.8%. [15] It ranged from 39.1% in the WHO's African region to 88.5% in the Americas, and from 41.9% in low-income countries to 87.3% in high-income ones. [15][27] Only 67 countries had cancer registries with real survival data, so the rest were estimated. [15]

Why it matters. Survival was lowest where breast cancer is found at a later stage. [15] The figures are meant as a starting point for the WHO's goal of cutting early breast cancer deaths by 2.5% a year. [15]

US cancer death rates fell 32% from 1991 to 2019. [16] A 2026 study of 2,954 counties in the British Journal of Cancer found that coastal, city and higher-income counties improved first and fastest. [16] The counties with the highest death rates to begin with also improved a lot. [16] The data came from more than 21 million cancer deaths on death certificates. [16]

Why it matters. The national fall is real, and where a person lives changed how much of it reached them. [16] The authors call for programmes aimed at the places left behind. [16]

Medicaid is US public health insurance for people on low incomes, and from 2014 most states widened who could get it. [28] A 2025 study compared 1,423,983 cancer cases in adults aged 18 to 59 in 26 states that widened it and 12 that did not. [28] Five-year survival rose more in the states that widened it, by about 2.6 percentage points more in rural areas and about 1.5 more in high-poverty areas. [28]

Why it matters. The gains were biggest for pancreatic, lung and bowel cancer. [28] As of June 2025, ten states, mostly in the South and Midwest, had still not widened it. [28]

A 2026 study linked US cancer registry data covering 85% of the population to county smoking rates, air pollution and social conditions. [29] People with lung cancer in counties where more than 20% of adults smoke had a 14% higher risk of dying than those in counties with the lowest smoking. [29] Living with fine air pollution above 12 micrograms per cubic metre also went with lower survival. [29]

Why it matters. The study used county figures, not each patient's own smoking, so it shows where the risk gathers rather than why. [29] The authors point to helping people quit and cutting pollution. [29]

Helmets, masks and beds that shine red and near-infrared light are sold for everything from ageing skin to ADHD, and one projection puts the market above $1 billion by 2030. [10] A 2025 review by more than 20 specialists found it worked for some ulcers, nerve damage, skin burns from radiation and pattern hair loss. [10] The US FDA has approved one device, for dry age-related macular degeneration, an eye disease. [10] Scientific American reviewed the science in March 2026. [10]

Why it matters. The leading idea is that an enzyme in mitochondria, the cell's power plants, absorbs the light and makes more energy. [10] Brain benefits have been seen in mice with a Parkinson's-like illness, but getting enough light through a human skull is still unsolved. [10]

Researchers used national health insurance records to follow 291,887 Koreans from age 30 to 40, then for about ten years more. [30] Those whose top blood-pressure number ran about 10 points above their peers for a decade had a 27% higher risk of heart disease after 40. [30] Their risk of kidney disease was 22% higher. [30] The work was presented at an American Heart Association meeting and reported on 4 April 2026, before peer review. [30]

Why it matters. Doctors quoted said raised readings in people under 40 are often watched rather than treated. [30] The study added up how high and how long, rather than using one reading. [30]

An analysis of data from 150,000 adults in the UK, the US and Scandinavia was reported by BBC Future in May 2026. [31] It estimated that five extra minutes a day of moderate activity could prevent about one in ten early deaths. [31] Moderate means brisk walking, cycling or climbing stairs. [31] The gain is largest for people who do almost nothing, and smaller for people who are already active. [31]

Why it matters. It is an estimate from data on how active people were, not a trial. [31] It points the same way as step-count studies, which find most of the benefit at the low end. [32]

A review of 57 studies with more than 160,000 people who wore step counters for several years found 7,000 steps a day brought most of the benefit linked to 10,000. [32] Compared with 2,000 steps, 7,000 went with a 25% lower risk of heart disease and a 47% lower risk of dying during the studies. [32] It was published in Lancet Public Health in August 2025. [32]

Why it matters. Going past 7,000 added only a modest extra benefit. [32] Like the stairs review, it shows a link, not proof that walking caused it. [32]

A review from Queensland University of Technology in Australia, accepted for publication in December 2025, read 14 studies on whether years of very long, hard exercise harm the heart. [33] Most found it was not harmful. Some found the benefit stops growing beyond a certain amount. [33] Only two suggested extra exercise could become harmful, and both had serious problems in how they were done. [33]

Why it matters. Every one of the 14 studies had possible sources of bias, which the authors say weakens them. [33] WHO guidelines advise at least 150 to 300 minutes a week of moderate activity. [33]

Endometriosis is tissue like the womb lining growing outside the womb, and it has few treatments that do not work through hormones. [34] Researchers looked for existing drugs that might act on a protein called ROR1, which is raised in endometriosis lesions. [34] Rimegepant, an approved migraine pill, slowed endometriosis cells in a dish. [34] In tissue grown from three patients' lesions, two responded and one did not. [34] The study was published in December 2025, after earlier work showed the drug shrank lesions in mice. [34]

Why it matters. Re-using a drug already approved for something else can be faster than inventing one. [34] Different answers from three patients' tissue show why a lab result is only a first step. [34]

A 2025 study pooled five long-running ageing studies covering 101,581 older people in 24 countries. [35] More social isolation went with lower scores on memory, orientation and planning tests. [35] The link was weaker in countries with stronger welfare systems and richer economies. [35] It was stronger among the oldest people, women and people with less money. [35]

Why it matters. The researchers used a method meant to reduce the chance that the link runs the other way, with failing memory making people withdraw, and the link held. [35] The WHO says isolation and loneliness affect about a quarter of older people. [36]

A 2025 review of 49 studies covering 729,043 people aged 60 or over found that 46% had two or more long-term illnesses at the same time. [37] The share was 48% in women and 41% in men, and lower in studies from China than elsewhere. [37] The WHO says there were 1.1 billion people aged 60 or over in 2023, and the number will nearly double by 2050. [36]

Why it matters. The WHO estimates that about 15% of adults aged 70 and over live with a mental disorder, most often anxiety or depression. [36] Being 70 or older raised the odds of having several illnesses at once. [37]

Johns Hopkins researchers hit living brain tissue with an electric pulse and froze it a fraction of a second later, to photograph brain cells passing messages. [38] They did it first in mouse tissue, then in tissue removed from six people having surgery for epilepsy. [38] The same recycling of tiny message-carrying bubbles seen in the mice was running in the human cells. [38] It was published on 24 November 2025 in the journal Neuron. [38]

Why it matters. The junctions where brain cells pass messages go wrong in Parkinson's disease. [38] The team hopes to compare inherited and non-inherited forms of the illness this way. [38]

Harvard researchers followed 5,370 US adults with an average age of 64 for nearly nine years, testing memory and attention every two years. [13] Those who reported eating the most ultra-processed food, such as sugary drinks, deli meats and fast food, had a 58% higher risk of dementia than those who ate the least. [13] Those eating the most whole, little-processed food had a 41% lower risk. [13] It was published on 3 June 2026. [13]

Why it matters. Diet was asked about once, at the start. [13] The study cannot show that the food caused the extra dementia cases. [13] Ultra-processed food is also linked to diabetes, high blood pressure and obesity, which are known risks for memory loss. [13]

An American Cancer Society study published on 2 September 2025 found more US men were diagnosed with prostate cancer from 2014 to 2021, reversing the fall from 2007 to 2014. [39] Advanced cases rose by 6% a year in men aged 55 to 69, and by 6.2% a year in men aged 70 and over. [39] Black men were twice as likely to die of it as white men. [39]

Why it matters. The researchers said screening rates, access to care, environment and genes could all help explain the gaps between groups. [39]