Most of what is known about dementia prevention comes from research carried out in wealthy countries. A new study of more than 214,000 people from 14 countries reveals that the most common modifiable risk factors for dementia vary greatly from one country to another, meaning that a one-size-fits-all approach to prevention will not work everywhere. The differences were striking: low educational attainment affected 85.6 % of people in China, but only 12 % in the United States; whilst a high body mass index affected 44.9 % of Americans, compared with just 13.3 % in India. Similar patterns were also observed across all regions, such as cardiovascular risks (high cholesterol and high blood pressure) and risk behaviours (smoking and drinking). The findings, presented today at the 2026 Alzheimer’s Association International Conference (AAIC) in London, are also published in the journal The Lancet Healthy Longevity.
The wildfire in Los Gallardos (Almería), which broke out on Thursday evening, has so far claimed 13 lives. Initial investigations suggest that a fallen power line may have been the cause of the fire. The blaze has burnt more than 3,000 hectares and has left 1,400 people displaced.
Sexually transmitted variants of the Shigella sonnei bacterium spread more rapidly than other strains, according to a study published in The Lancet Infectious Diseases. This study of more than 3,500 samples collected in the United Kingdom between 2016 and 2021 also observed that strains resulting from sexual transmission were more resistant to the antibiotic azithromycin in men who have sex with men than in other patient groups. The bacterium S. sonnei causes an acute diarrheal infection called shigellosis; it is known to cause traveler’s diarrhea, and over the past two decades, cases have increased as a sexually transmitted disease among men who have sex with men (MSM).
An international team analyzed data from 262 clinical trials involving 100,000 people, which evaluated a total of 19 currently available obesity drugs, including GLP-1 analogs such as semaglutide and tirzepatide. Overall, the results indicate that, despite substantial weight loss, most of the drugs do not significantly improve quality of life, and few show cardiovascular benefits after one year of treatment. Furthermore, those that achieved greater weight loss were often associated with more side effects. The study is published in The BMJ.
Targeted marine cloud bleaching is a proposed geoengineering method to increase the amount of light reflected by clouds and reduce the heat reaching Earth. A US team has taken advantage of a natural experiment that generated this effect—through aerosols produced by the massive Australian bushfires of 2019 and 2020—to study the possibilities and risks of using it to modify an extreme weather event like El Niño. According to the models used in the study, its early application could weaken El Niño, but it could also have unintended consequences, such as altering the timing and increasing the magnitude of the subsequent La Niña event. The work is published in Science Advances.
Rising sea temperatures are promoting the spread of Vibrio vulnificus, the marine bacterium nicknamed the “carnivore,” which can cause serious infections. Last summer, the European Center for Disease Prevention and Control (ECDC) warned of an increased risk during the summer months, especially in the Baltic Sea. This bacterium has also been identified along the Spanish coast, but experts explain that swimming in the Mediterranean is safe for the general public, as the bacterium thrives in waters with lower salinity. Even so, they recommend that vulnerable individuals remain vigilant and avoid swimming if they have open wounds.
A Spanish study rules out men’s lifestyle habits as an explanation for geographical differences in semen quality. The findings, presented at the annual congress of the European Society of Human Reproduction and Embryology (ESHRE), the abstract of which is to be published today in the journal Human Reproduction, are based on data from 386 men who attended seven assisted reproduction centres across the country between June 2024 and December 2025. They answered questions about their lifestyle habits (physical activity, tobacco use, alcohol consumption, coffee intake, etc.), their place of residence and their body mass index, amongst other factors. Semen quality was higher among men from northern Spain, even though lifestyle habits were similar across all regions, suggesting that differences in quality may be due to exposure to environmental pollutants, says the lead author.