Scientists in Hong Kong have studied the usefulness of six indices that estimate the severity and health hazard of a heatwave. Analysing several episodes in recent years in Spain, India and the United States, they conclude that five of the six were not able to capture their severity and spatial distribution effectively enough, especially in low humidity conditions. The most useful was the so-called "lethal heat stress index", but the researchers - publishing their results in the Cell group's journal Nexus - say that it too can be improved and that a more global framework is needed to mitigate dangerous heatwaves.  

A team of researchers has analysed data from more than 650,000 residents in Sweden and concluded that the genetic predisposition of peers - especially in high school - influences one's risk of developing anxiety, depression or drug abuse in the future. According to the authors, who publish the results in the American Journal of Psychiatry, this relationship appears "even after controlling statistically for whether peers were affected or not". 

Climate tipping points are thresholds at which elements of the Earth could reach a point of no return, accelerated by climate change and with consequences for the rest of the planet. These drastic changes could affect, for example, the Atlantic Meridional Circulation (AMOC), polar ice sheets or tropical rainforests. A study published in Science Advances concludes that there is too much uncertainty to extrapolate historical data and reliably estimate when these inflections will occur.
 

Vision loss and having high cholesterol - the so-called ‘bad’ cholesterol - are risk factors for developing dementia, according to a meta-analysis published in The Lancet. Eliminating these risk factors could reduce dementia cases by 2% and 7% respectively, the study says. Both factors are in addition to 12 others previously mentioned in a 2020 report such as less education, physical inactivity, hearing loss, excessive alcohol consumption, obesity or poor social contact, among others. According to the research, almost half of all dementia cases could be prevented or delayed if these risk factors were controlled.

24% of girls aged 15 to 19 who have been in a relationship have experienced physical or sexual violence by a male partner at some point in their lives, according to a global study with data from 161 countries between 2000 and 2018. Spain is in the group with the lowest prevalence (12% over their lifetime; 4% in the previous year), according to 2015 data. There is less violence against girls in countries with higher incomes, higher rates of girls in secondary education, and greater gender equality in inheritance laws, says the study published in The Lancet Child & Adolescent Health. 

Eating a vegan diet for eight weeks is associated with reductions in biological age estimates based on levels of DNA methylation, a type of chemical modification of DNA that alters the expression of genes, but not the DNA itself. This is the main conclusion of a study published in BMC Medicine in which 21 pairs of twins participated in a clinical trial. Of each pair, one person followed an omnivorous diet and the other a vegan - and lower calorie - diet during that period.

The European Medicines Agency (EMA) has recommended not granting marketing authorization for Leqembi™ (lecanemab) for the treatment of Alzheimer's disease. The EMA's Committee for Medicinal Products for Human Use (CHMP) considers that its effect in delaying cognitive decline does not outweigh the risk of serious side effects associated with the drug, in particular swelling and possible bleeding in patients' brains. Leqembi™ was approved in 2023 in the United States.

After the introduction of a shingles vaccine (Zostavax) in 2006, several studies suggested that the risk of dementia might be lower in people who had received the vaccine, although the results were inconclusive. In many countries Zostavax has been withdrawn and replaced by a much more effective vaccine (Shingrix). A study published today in Nature Medicine suggests that this new recombinant shingles vaccine, Shingrix, is associated with a greater reduction in the risk of dementia compared to Zostavax and vaccines against other types of infections.

Studies associating the consumption of low amounts of alcohol with health benefits are not of good scientific quality, says a meta-analysis pooling the findings of 107 previous papers. For example, studies may use a reference group of older adults who have given up or limited alcohol for health reasons. Compared to those who continue to drink, the latter appear to be in better health, notes the article, published in the Journal of Studies on Alcohol and Drugs.

Japanese scientists have developed tiny liver organoids from stem cells that, transplanted into mice, integrate with the original organ and help repair fibrotic lesions. This scar-like tissue damage is common to many liver diseases, such as fatty liver disease and cirrhosis. According to the authors, who publish their results in the journal Science Translational Medicine, such organoids could offer an alternative to liver transplants in the future.