Women face genetically higher depression risk

Hello Health Rounds readers! Today we report on genetic differences that help explain higher rates of depression among girls and women. We also feature two studies presented at a large meeting of gastroenterologists in Berlin. One looked at the potential effects of microplastics on microbes in the intestines, while the other studied the connection between artificially-sweetened and low-sugar beverages and fatty liver disease.

Among the breaking news stories from our Reuters colleagues: US health official calls for separating measles combination shots; measles-free status in jeopardy in the Americas; Trump voters balk at restricting traditional vaccines; US Supreme Court to examine gay 'conversion therapy' ban; and immune system breakthrough wins Nobel medicine prize.

Also: Gaza babies forced to share oxygen masks as Israel blocks equipment; dengue cases surge across Bangladesh; police in India launch manslaughter probe into cough syrup deaths; and at least 15 million teens use e-cigarettes worldwide.

Mary Brunkow, Fred Ramsdell and Shimon Sakaguchi have won the 2025 Nobel Prize in Physiology or Medicine for work shedding light on how the immune system spares healthy cells, creating openings for possible new treatments for autoimmune diseases and cancer.

Genetic factors contribute more to depression risk in females than in males, according to a large Australian study that may help further understanding of why women are more likely to suffer from the condition.

Analyzing DNA samples from nearly half a million people, researchers found roughly twice as many genetic 'flags' for depression in females compared with males, the research team reported in Nature Communications.

"We already know that females are twice as likely to suffer from depression in their lifetime than males," study leader Dr. Brittany Mitchell of QIMR Berghofer Medical Research Institute in Brisbane said in a statement.

"Until now, there hasn't been much consistent research to explain why depression affects females and males differently, including the possible role of genetics," Mitchell said.

The team identified about 7,000 changes in DNA that could cause depression in both sexes, and about a further 6,000 DNA changes that could cause depression in females only.

The researchers also found that the genetic factors linked to depression overlap more with genes for metabolic traits in females than in males.

The differences may help explain why females with depression more often experience metabolic symptoms such as weight changes or altered energy levels, they said.

The researchers say most drug trials and therapies are tested on males, and they hope their work will also translate to a greater clinical understanding of female depression.

"These findings underscore the importance of considering sex-specific genetic (factors) in the study of health conditions, including major depressive disorder, paving the way for more targeted treatment strategies," the researchers concluded.

Tiny pieces of plastic that find their way into human intestines can adversely impact the healthy bacteria and other microbes that naturally live there, known as the gut microbiome, laboratory experiments suggest.

Some of the microplastic-induced changes in gut microbes observed in test tubes were similar to changes seen with depression, colorectal cancer, and other diseases, researchers reported at the ongoing United European Gastroenterology (UEG) Week meeting in Berlin.

Earlier studies have found microplastics in stool samples and colon biopsies in a significant proportion of volunteers.

The new study used stool samples from five healthy volunteers to grow gut microbiome cultures in the lab. The cultures were then exposed to five common types of microplastic particles at concentrations reflecting estimated human exposure.

For the most part, total bacterial counts did not change. However, the microplastic-treated cultures showed significant drops in pH levels, indicating altered microbial metabolic activity, researchers found.

They also saw microplastic-specific shifts in bacterial composition, with certain bacterial groups increasing or decreasing depending on the microplastic type.

Shifts in bacterial composition were accompanied by changes in bacterial production of chemicals that nourish intestinal cells, aid in digestion of food and processing of medications, and influence mood and brain function.

The researchers don't yet know how microplastics induce these effects. And their study did not look at long-term effects of microplastics exposures on gut bacteria, nor did it consider the effects of additional factors like diet and immune response.

"The key takeaway is that microplastics do have an impact on our microbiome," study leader Christian Pacher-Deutsch of the Medical University of Graz, Austria said in a statement.

"While it's too early to make definitive health claims, the microbiome plays a central role in many aspects of well-being, from digestion to mental health. Reducing microplastic exposure where possible is therefore a wise and important precaution," he concluded.

Substituting low-sugar or artificially sweetened drinks for sugary drinks does not protect against fatty liver disease, a large study from China suggests.

Both sugar-sweetened beverages and low- or non-sugar-sweetened beverages are significantly associated with a higher risk of developing metabolic dysfunction-associated steatotic liver disease (MASLD), researchers reported in Berlin at UEG Week 2025.

In MASLD, fat accumulates in the liver, potentially causing hepatitis and liver failure. The fatty liver condition affects more than 30% of people worldwide and is a rapidly increasing cause of liver-related deaths.

The new study tracked 123,788 UK volunteers without liver disease at baseline. During a median 10.3 years of follow-up, participants periodically completed questionnaires about the food and drinks they regularly consumed.

Over the course of the study, 1,178 participants developed MASLD and 108 died from liver-related causes.

Intake of low- or non-sugar-sweetened beverages and sugar-sweetened beverages of more than 330 grams (11 ounces) per day was associated with significantly higher risks of developing MASLD.

Both beverage types were also associated with higher liver fat content, although a study like this cannot prove the drinks caused the liver disease.

Sugar-sweetened beverages "have long been under scrutiny, while their 'diet' alternatives are often seen as the healthier choice," study leader Lihe Liu of the First Affiliated Hospital of Soochow University said in a statement.

"Our study shows that low- or non-sugar-sweetened beverages were actually linked to a higher risk of MASLD, even at modest intake levels," she added.

This newsletter was edited by Bill Berkrot; additional reporting by Shawana Alleyne-Morris.

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