Mind & body, in brief

A team at King's College London's psychiatry institute pooled 63 studies of more than 265,000 people. [1][3] Cannabis users were about twice as likely as non-users to have committed violence. [1]

Among people in psychiatric care, users were about two and a half times as likely to be violent as patients who did not use cannabis. [1]

For violence that led to a criminal conviction, users were three to four times as likely to be convicted, but only a few studies measured convictions. [1]

Users were also about one and a half times as likely to be victims of violence. That link was stronger for women than for men. [1]

The review counted physical, sexual and psychological violence, inside and outside relationships, using the World Health Organization's broad definition. [1]

The link held in studies that followed people over time. It was smaller there than in studies that looked at a single moment. [1]

The review shows a link, not a cause. Other drugs, alcohol and hard circumstances often go with cannabis use, and they may raise the risk of violence too. [1]

Few of the studies measured how much or how often people used cannabis. Most were done before high-strength cannabis became common. [1]

In Denmark, THC, the main mind-altering chemical in cannabis, rose from 8.3% to 31.2% of seized cannabis resin between 2000 and 2022. [2]

In a Danish national records study, years with stronger cannabis went with more diagnoses of psychosis caused by cannabis. [2]

An earlier King's study, from 2019, linked 12% of new psychosis cases in 11 European places to high-strength cannabis, and 30% in London. [3]

The review's authors want mental health services to ask about cannabis when they judge someone's risk of violence. They also want public health messages about cannabis to mention violence. [1]

Why it matters. Watch whether new studies measure how much cannabis people use and how strong it is, which the review could not do, and whether mental health services add cannabis to their violence risk checks. [1]

Pennsylvania, a US state, reported its fifth measles-linked death of 2026 on 30 September: an unvaccinated person in Lancaster county. [5] Its outbreak has reached 943 confirmed cases and 176 hospital stays across 39 counties. [5] The US Centers for Disease Control and Prevention (CDC), the national disease agency, listed more than 3,600 cases nationwide but two deaths. [6] In early September the CDC said it would count measles deaths from official death records, rather than relying only on state reports, breaking with past practice. [7]

Why it matters. Pennsylvania asked the CDC for emergency help and said it could withdraw the request unless the agency recognises the state's deaths. [5] Robert F Kennedy Jr, the US health secretary, first called the state's announcement premature. [7]

Retatrutide, an experimental drug made by Eli Lilly, copies three gut hormones that help control hunger, blood sugar and energy use. [8][9] Wegovy, an existing weight-loss drug, copies one of them, and Mounjaro copies two. [8] In an 80-week trial of 1,152 adults with obesity and type 2 diabetes, people on the top weekly dose lost 18.8% of their body weight, against 5.1% on a dummy injection. [9] The results were published in the Lancet. [9] Lilly says it will ask regulators to approve the drug early next year. [8]

Why it matters. Diarrhoea affected 27-34% of people on the drug, against 13% on the dummy, and Lilly paid for the study. [9] It is the first drug acting on three of these hormones to be tested in a phase 3 trial, the large test US regulators need before they will consider approving a drug. [8]

About 51% of the world's people breathed 'very poor' or 'extremely poor' levels of ground-level ozone over the past six months, the Copernicus Atmosphere Monitoring Service, which tracks air quality worldwide, said on 29 September. [10] Both levels are above the World Health Organization's limits. [10] High in the sky, ozone blocks harmful sunlight. Near the ground it is the main part of smog and can damage the lungs. [10] It forms when pollution from burning fuel or wildfires meets sunlight and heat. [10]

Why it matters. Asia was worst, with 75% of people exposed to at least very poor levels. [10] The gases that make ozone cross borders, which makes it harder for any one country to cut. [10]

Maricopa County, which includes Phoenix in the US state of Arizona, has confirmed 275 heat deaths so far this year, 76% more than at this point last year. [11] More than 500 other deaths are still being checked. [11] The yearly record is 645, set in 2023, and the number had fallen for two years since. [11] The county's medical examiner says nights that stay above 90F (32C) several days in a row seem riskiest; Phoenix had 29 such nights this year. [11]

Why it matters. Officials count all of these deaths as preventable. [11] Phoenix has paid for longer cooling-centre hours partly with pandemic-era federal money, which runs out at the end of this year. [11]

Medicare is the US government's health insurance for people aged 65 or over. [38] About one in four people with dementia on Medicare may be getting antipsychotics or other brain-altering drugs that are not right for them, a study in JAMA estimated. [12] Antipsychotics are approved mainly for schizophrenia, and the US Food and Drug Administration warns they raise the risk of death in older people with dementia. [12] NPR reported on Marjorie Tingley, 85, whose Michigan care home pushed to sedate her and then gave her an eviction notice. [12]

Why it matters. Her sons are suing, and the care home denies their claims. [12] Nearly half of the 1 million people in US assisted living have dementia, and families there can face a choice between agreeing to the drugs and losing the place. [12]

On 15 July the World Health Organization (WHO) updated its guidelines on lowering the risk of dementia, the first update since 2019. [13] It says up to 45% of dementia risk is linked to things that can change, such as smoking, alcohol, loneliness, inactivity, high blood pressure and air pollution. [13] It newly recommends cutting exposure to air pollution, and says hearing aids may be offered. [13] It does not recommend vitamin B or E, omega-3 or multivitamin pills for this, unless a person lacks them. [13]

Why it matters. More than 57 million people live with dementia, and nearly 10 million are diagnosed each year. [13] It costs the world about US$1.3 trillion a year, and about half of that is unpaid care by families. [13]

Glucosamine is a supplement widely sold for joint health, and in the US it is regulated less strictly than prescription drugs. [14] In June a team writing in Nature Metabolism reported that brains with Alzheimer's disease carry too many sugar chains on their proteins. [14][15] Giving glucosamine, which the body uses to build those chains, made memory problems worse in mice bred to get the disease. [14] In University of Florida health records, people with dementia who took glucosamine had a 25% higher risk of dying. [14]

Why it matters. Health records show a link, not a cause, and the higher death risk did not show up in people with milder memory loss. [14] The researchers say the sugar-chain build-up could become a target for treatment. [14]

Which?, a British consumer group, checked 26 supplements sold for menopause by shops such as Boots, Holland & Barrett and Amazon. [16] None held the right nutrients in the right doses to back their use for menopause. [16] The dearest, at £485 a year, contained no calcium or magnesium, while an Asda multivitamin at £22 a year held both. [16] Calcium and vitamin D matter most at menopause, because they support bones as oestrogen falls. [16]

Why it matters. A trade body for the makers said food supplements must follow the food rules that apply to them. [16] A separate UCL check of 201 such products found fewer than half contained vitamin D and calcium. [16]

IVF clinics sell extras such as tests of embryos' chromosomes, growth hormone shots and blood-plasma injections. [17] Surveys in Britain and Australia found at least three in four IVF patients had tried one. [17] A review of 10 popular extras found three made little or no difference to the chance of a baby, four had mixed or weak evidence, and three showed a possible benefit. [17] One US patient, Alessandra Dowling, estimates she spent close to $200,000 on fertility care including extras. [17]

Why it matters. In the US, insurance rarely covers IVF and the national health research agency long restricted embryo studies. [17] So research on the extras happens in a setting much more driven by market forces, with clinics competing, said Marcelle Cedars, a fertility doctor at the University of California, San Francisco. [17]

A study in Nature Medicine pooled 1,038 patients from 26 centres with advanced melanoma, a skin cancer, that could still be removed by surgery. [18] Most got immune drugs, which help the body attack the cancer, before their operation. [18] Five years later, 83% to 88% of those on immune drugs were alive. [18] Among patients whose tumour had largely died off by the time of surgery, about 98% were alive. [18]

Why it matters. Those patients gained nothing from staying on the drugs after surgery. [18] Giving immune drugs before the operation is now the standard treatment for this stage of melanoma. [18]

Jehovah's Witnesses, a religious group, have refused blood transfusions under a rule dating from 1945. [19] Since 18 September members may decide for themselves whether to accept red cells, white cells, platelets or plasma from a donor, according to a letter in the BMJ on 30 September. [19] A March update had already left the use of a patient's own stored blood to personal conscience. [19] Whole donor blood is still forbidden. [19]

Why it matters. For decades hospital records have carried 'no blood' alerts that assumed a Witness would refuse all four blood parts. [19] The letter's author says those assumptions must now change. [19]

The US National Health Interview Survey has asked Americans about their health every year since 1957. [20] A redesign proposed in August by the CDC's statistics centre would cut its questions from 482 to 150. [20] It drops questions on hearing aids, tiredness, thinking, and wheelchairs or scooters, though more than a quarter of Americans have a disability. [20] The US health department said the changes were driven by the cost of collecting data. [20]

Why it matters. A paper co-written by CDC statisticians found the survey may already miss 75% of people with intellectual and developmental disabilities. [20] Disability groups say the redesign would make that undercount worse. [20]

The NHS board for West Yorkshire, covering Leeds, Bradford and three other areas of England, now makes people wait at least two years for an ADHD or autism assessment. [21] ADHD is attention deficit hyperactivity disorder. [21] The charity ADHD UK has sent the board a legal letter calling the rule unlawful and threatening a court case. [21] It says the board broke equality law and patients' right to choose another provider. [21]

Why it matters. Three other English boards have set minimum waits and 11 ration assessments in other ways, as costs rise with demand. [21] A government review led by Prof Peter Fonagy is expected to suggest support without a formal diagnosis first. [21]

Science, a leading research journal, published a special issue on women's health on 1 October. [22] One review looks at why women have pain with no clear injury behind it at about twice the rate of men, pointing to sex hormones, links between immune cells and nerves, and gut bacteria. [22] Another argues that the X and Y chromosomes shape ageing and disease enough to be considered whenever treatments are matched to each patient. [22] Others cover menopause and pregnancy. [22]

Why it matters. The editors named funding cuts to women's health research as one reason for the issue. [22] One editor said heart and metabolic disease were left out because too little is yet known about how sex changes them. [22]

In August the US health department published a report suggesting that support for gender-affirming care, the accepted medical care for transgender people, may go with support for political violence. [23] It was not peer reviewed, and its data and funding have not been released. [23] It rests on a paid online survey of about 1,200 adults. [23] Liliana Mason, a political psychologist at Johns Hopkins University, said she would recommend rejecting it. [23] She said its sample held too many Democrats compared with the US population. [23]

Why it matters. A large body of evidence shows transgender people are far more often victims of violence than perpetrators, NPR reported. [23] Co-author Colin Wright said the report will be sent to a journal. [23]

Robert F Kennedy Jr, the US health secretary, said on 28 September that Americans' medical and lifestyle records should be joined up and searchable by AI. [24] He named vaccines, food and chemicals as things to test against chronic illness and autism. [24] He said officials already use records from Medicaid, a US government health scheme with tens of millions of children in it, and a CDC vaccine-safety database. [24] He spoke at an event run by the Maha Institute, a group whose head has called himself an anti-vaxxer. [24]

Why it matters. Kennedy is a long-time vaccine sceptic, and officials have set up an autism registry despite wide protest. [24] Joining records this way also opens them to government and outside use. [24]

Psilocybin is a psychedelic drug. [25] A study in Nature scanned 62 people who had never taken a psychedelic, before and after a dose, while they rested, meditated, listened to music and watched a film. [25] On the drug, their brain activity lined up more closely with what they were doing. [25] The effect was strongest in people who said the line between themselves and the world faded, and it predicted shifts in their mindset the next day. [25]

Why it matters. The stronger effect did not go with anxiety or confusion. [25] The authors call the state 'embeddedness'; it comes from one study of 62 volunteers. [25]

During deep sleep, the fluid around the brain and spinal cord moves in large waves, in time with slow brain waves. [26] Levitt and colleagues played sounds to sleeping volunteers inside an MRI scanner, timed to the peaks of those slow waves. [26] The sounds made the slow waves stronger, and fluid flow rose to match. [26] The study ran in Science Translational Medicine and was summarised in Nature Neuroscience on 1 October. [26]

Why it matters. Poor fluid flow is a feature of some brain diseases, so the authors see a possible treatment. [26] This test measured flow in healthy sleepers, not any effect on disease. [26]

A study in Nature in May compared how long UK Biobank volunteers aged 37 to 84 said they slept with 23 measures of how old their organs looked. [27] The pattern was a U: short and long sleepers both looked older inside. [27] The youngest-looking organs went with 6.4 to 7.8 hours a night, varying by organ and sex. [27] Under six hours or over eight went with more depression, diabetes and deaths. [27]

Why it matters. Sleep length was self-reported. [27] A genetic test gave no strong sign that illness causes the unusual sleep, but it could not rule that out. [27]

Each malaria season millions of African children take two malaria drugs together, sulfadoxine-pyrimethamine and amodiaquine, to prevent infection. [28] A study pooled blood tests from 934 children in Uganda, Mozambique and Burkina Faso. [28] Infection was most closely tied to how much of amodiaquine's breakdown product was in the blood. [28] Children with low levels had nearly twice the risk of infection by day 28. [28]

Why it matters. The other drug showed only weak links in all three countries, whatever resistance genes their parasites carried. [28] The authors say its role in single doses needs a fresh look. [28]

Semaglutide, the drug sold as Ozempic and Wegovy, is known to protect the kidneys of people with type 2 diabetes and kidney disease. [8][29] A 52-week trial in 106 such people scanned their kidneys before and after, and took samples from some, to find out how. [29] Its three main scan measures, oxygen, blood flow and inflammation, did not change. [29] Other measures suggested the drug slowed scarring and acted on cells lining the kidney's filters. [29]

Why it matters. The trial was built to explain the kidney benefit. [29] Its main measures missed, so the explanation now rests on smaller clues. [29]

In sleep apnoea a person stops breathing for 10 seconds or more during sleep, and a CPAP machine is one treatment. [37] CPAP stands for continuous positive airway pressure. [30] A review published on 1 October pooled trials in adults starting CPAP. [30] It lowered CRP and IL-6, two blood signs of inflammation, and LDL, the 'bad' cholesterol. [30] The evidence was rated low certainty. [30]

Why it matters. A possible drop in insulin resistance did not hold up when the authors checked how solid it was. [30]

In rheumatoid arthritis, a disease that inflames the joints, many patients still hurt after drugs have brought the inflammation down to low levels. [31] A review of studies, published in January in the journal Cureus by Japanese researchers, found that adding more anti-inflammatory drugs often did not fix that pain. [31] Some drugs that block the immune signal IL-6 helped a little in some patients. [31] Exercise and physical therapy gave more consistent relief, with few and mild side effects. [31]

Why it matters. The authors say the gap points to causes beyond the inflamed joint. [31] Most of the studies they found were small, or were not designed to measure pain. [31]

Social anxiety disorder affects up to 12% of people at some point in their lives, the BBC reported on 30 September. [32] Research by the universities of Chichester, Coventry and UCL linked it to lower grades and poorer relationships among students, more than a fifth of whom face some social anxiety. [32] A talking therapy called CBT is considered the best treatment, and the NHS offers it. [32] Oxford psychologist David Clark says habits that feel protective, such as rehearsing every sentence or avoiding eye contact, make it worse. [32]

Why it matters. Social Anxiety Alliance UK says many people treat it as a personality flaw rather than as a condition that can be treated. [32]