Medical Bulletin 09/ April/ 2025 - Video

Long-term exposure to high levels of air pollution may harm the brain health of older adults in England, finds a new study led by UCL researchers. Findings are published in The Journals of Gerontology: Series A. The study found that exposure to nitrogen dioxide (NO₂) and fine particulate matter (PM_2.5) is linked to lower scores in key cognitive abilities, particularly language skills.

The researchers analysed data from 1,127 adults aged 65 and over who took part in the ELSA Harmonised Cognitive Assessment Protocol in 2018. The team examined exposure to air pollution over an eight to 10-year period and assessed participants’ memory, executive function, language, and overall cognitive function.

Participants completed a range of well-established neurocognitive memory assessments such as the “East Boston Memory Test” and the “Wechsler Memory Scale”, alongside immediate and delayed recall, backwards counting tasks, and shape drawing.

The findings showed that individuals residing in areas with the highest levels of NO₂ and PM_2.5 performed worse on cognitive tests compared to those living in areas with average pollution levels. The most compelling evidence of association was observed in language skills, with individuals in the most polluted areas scoring in the bottom third of the cognitive tests performed.

The study also found that different sources of air pollution have varying effects on cognitive health.

Lead author Dr Giorgio Di Gessa (UCL Epidemiology & Health) said: "Our study shows that air pollution is not just harmful to the lungs and heart but also to brain health, especially when people are exposed to high levels for long periods.

“The most consistent links we found were with language ability, which may indicate that certain pollutants have a specific effect on particular cognitive processes."

Reference: Giorgio DI GESSA, Mikaela Bloomberg, Rina So, Shaun Scholes, Thomas Byrne, Jinkook Lee, Sara D Adar, Paola Zaninotto, Cognitive Performance and Long-term Exposure to Outdoor Air Pollution: Findings from the Harmonised Cognitive Assessment Protocol Sub-Study of the English Longitudinal Study of Ageing (ELSA-HCAP), The Journals of Gerontology: Series A, 2025;, glaf060,

Study Unveils Benefits of Elemental Diet in Healing Gut Microbiome

A new study has found that palatable elemental diet significantly impacted the gut microbiome. In case of small intestinal bacterial overgrowth and intestinal methanogen overgrowth palatable elemental diet improved symptoms, reduced microbial gas production and modulated the microbiome. The findings are published in the peer-reviewed journal Clinical Gastroenterology and Hepatology.

The research tested the elemental diet's effectiveness and explored whether improving its unappealing taste -- a major barrier -- could help patients adhere to the diet's stringent protocol. The elemental diet is a special low-fat liquid formulation that is designed to be easily digested and contains all the essential nutrients necessary for a healthy diet.

Small intestinal bacterial overgrowth and intestinal methanogen overgrowth typically occur when harmful bacteria or methane-producing microbes grow out of control in the gut.

In this study, 30 adults ages 18 to 85 diagnosed with Small intestinal bacterial overgrowth or intestinal methanogen overgrowth strictly adhered to only a more palatable version of the elemental diet for two weeks. This was followed by two weeks during which study participants resumed their normal diet. The researchers analyzed changes in the gut microbiome, how well the diet was tolerated, symptom relief and breath test results, along with tracking any side effects.

Most participants reported tolerating the diet well, with no serious side effects. A key finding was a reduction in unfavorable microbes linked to gut issues. Methane levels also dropped significantly, with many returning to normal.

In addition, 83% of participants reported feeling better, with significant relief from common symptoms like bloating and discomfort. These findings suggested that a tastier version of the elemental diet helped restore balance in the gut and eased symptoms of Small intestinal bacterial overgrowth or intestinal methanogen overgrowth.

"The study's positive results suggest that enhancing the palatability of the elemental diet could make it more accessible and practical for patients, improving adherence and quality of life for those who face significant challenges with traditional therapies," said Mark Pimentel, MD, study author and executive director of the MAST Program at Cedars-Sinai.

Reference: new-cedars-sinai-study-shows-how-specialized-diet-can-improve-gut-disorders/

Severe Obesity May Be Linked to Increased Risk of 16 Common Health Conditions

A new study has found that obesity, particularly severe obesity, is strongly associated with the incidence of 16 common health outcomes. Associations remained consistent across sex and racial groups. Strong associations were observed for obstructive sleep apnea, type 2 diabetes, and metabolic dysfunction-associated steatotic liver disease. The findings are published in NEJM Evidence.

Researchers conducted a longitudinal cohort study to understand how different levels of obesity relate to a wide array of health conditions across a diverse U.S. population. Data were analyzed from 270,657 participants enrolled in the All of Us research program.

Participants contributed electronic health records, physical measurements, and survey data. Body mass index (BMI) was calculated at enrollment and used to classify individuals as normal weight, overweight, or obese, with further stratification into obesity classes I, II, and III.

Sixteen pre-identified health conditions were evaluated: hypertension, type 2 diabetes, hyperlipidemia or dyslipidemia, heart failure, atrial fibrillation, atherosclerotic cardiovascular disease, chronic kidney disease, pulmonary embolism, deep vein thrombosis, gout, liver disease linked to metabolic dysfunction, biliary calculus, obstructive sleep apnea, asthma, gastroesophageal reflux disease, and osteoarthritis.

Obesity was present in 42.4% of the study population, including 21.2% with class I obesity, 11.3% with class II, and 9.8% with class III. Compared to those with normal weight, individuals with obesity were more likely to be female, Black, have lower income and education levels, and have higher blood pressure and waist-to-hip ratios.

Prevalence and incidence rates increased progressively with higher obesity classes for all 16 health outcomes. Observed associations with class III obesity were strongest for obstructive sleep apnea, type 2 diabetes mellitus, and metabolic dysfunction–associated liver disease. Weaker associations were found for asthma, osteoarthritis, and atherosclerotic cardiovascular disease.

Increased risk, particularly at higher severity levels, was associated with all 16 health outcomes studied. Risks rose in a stepwise manner across obesity classes, with the highest burden observed among individuals with class III obesity.

Reference: Christopher N. Schmickl,, Janna Raphelson,, Atul Malhotra, Forty Percent and Rising — Why Every Specialist Must Care about Obesity, NEJM Evidence, 4, 4, (2025).