An early first menstrual period (menarche) - compared with the average of 13 years - is associated with an increased risk of type 2 diabetes in women under the age of 65 and also with an increased risk of stroke among those living with diabetes, says a study published in BMJ Nutrition, Prevention & Health. The research analyses data from a national health survey in the US, focusing on women aged 20-65 between 1999 and 2018.

At the current level of emissions, there is a 50% chance that global temperatures will exceed the 1.5°C target consistently over seven years. This is one of the forecasts in the Global Carbon Budget 2023 report, which estimates that CO₂ emissions from fossil fuels will reach record highs in 2023, reaching 36.8 billion tonnes, 1.1 % more than in 2022. The report, published in the journal Earth System Science Data, shows that emissions have decreased in the EU as a whole and in the United States, while they continue to increase in India and China.

People who do not have coeliac disease or wheat allergy sometimes reduce their gluten intake because they believe it is the cause of their gastrointestinal symptoms. A study has found that there may be a nocebo effect - negative anticipation of a substance or treatment, the opposite of the placebo effect - on gluten sensitivity in these people, so that the mere thought of ingesting gluten causes more symptoms in those who believe they are sensitive to it. The results are published in the journal The Lancet Gastroenterology & Hepatology.

In a recent study of the experiences of biomedical researchers in Spain, 43% of respondents admitted to having intentionally committed some form of scientific misconduct. The most frequent kind of misconduct was false authorship of scientific articles: 35% of the 403 respondents said they had been involved in some instance of it, says the study published in the journal Accountability in Research. Ten per cent of respondents reported a lack of informed consent, and 3.6 per cent admitted to having been involved at least once in falsification or manipulation of data.

A review including 126 studies shows an association between the use of social networking sites by 10-19 year olds and increased risk behaviours, including alcohol, tobacco and other drug use, risky sexual behaviour, gambling and antisocial behaviour. According to the authors, who acknowledge that their research does not establish causality, "precautions may need to be taken in academia, government, health and education before the risks of adolescent use of social networking sites are fully understood". The findings are published in The BMJ.

The increase in remote collaboration among scientists is associated with a decrease in innovative discoveries compared to teams working together in person at the same location. These are the conclusions of an analysis of 20 million research articles and four million patent applications published in Nature today.

The US Food and Drug Administration (FDA) has issued a statement reporting that it has received reports of T-cell tumours in patients who received various CAR-T cell treatments. As quoted in the statement, "although the overall benefits of these products continue to outweigh their potential risks for their approved uses, FDA is investigating the identified risk of T cell malignancy with serious outcomes, including hospitalization and death, and is evaluating the need for regulatory action".

According to research published in the journal Nature Communications, the magnitude 7.8 earthquake that was felt in parts of Turkey and Syria in February this year emitted detectable signals eight months before it struck. Although it is currently not possible to predict the magnitude, time and location of earthquakes in the short term, these results would indicate that some large earthquakes may show a detectable preparation phase. However, the authors admit that, due to the large number of variables, recognising these signals and using them for medium-term earthquake prediction remains a challenge.

The injection of a type of stem cell into the brains of patients living with progressive multiple sclerosis (MS) is safe, well-tolerated, and has a lasting effect that appears to protect the brain against further damage, according to an early-phase trial published today in the journal Cell Stem Cell.

Since mid-October, northern China has reported an increase in influenza-like illness compared to the same period in the previous three years. On 21 November, the media and the ProMED system reported outbreaks of pneumonia of undiagnosed cause in children in northern China. According to the World Health Organization (WHO), it is unclear whether these are related to the overall increase in respiratory infections previously reported by the Chinese authorities or are separate episodes. In a statement, the WHO has officially requested detailed information from China on this increase in respiratory illnesses and outbreaks of childhood pneumonia.