Medical Bulletin 27/Jun/2025 - Video

Here are the top medical news for the day:

Staying Active May Delay Cognitive Decline by Years: Study Finds

A new study published in the Journal of Prevention of Alzheimer’s Disease has found that regular physical activity may play a crucial role in slowing cognitive decline among older adults. Researchers from the University of Georgia’s College of Public Health analyzed data from over 13,000 individuals and concluded that long-term engagement in physical activity can help preserve brain function and delay dementia onset.

The study, led by Suhang Song, an assistant professor in the Department of Health Policy and Management, used data from the Health and Retirement Study—a large, nationally representative survey that tracked adults aged 50 and older over a period of 16 years. Participants were asked how frequently they engaged in physical activity, categorized by intensity: vigorous (such as jogging), moderate (like dancing or gardening), and mild (such as housework).

“We found that longer and more frequent engagement in physical activity was associated with delayed cognitive decline,” said Song. “These protective benefits grew over the length of the study.”

Importantly, even low levels of regular activity made a difference. The study showed that increasing vigorous physical activity from a few times a month to once a week, or moderate activity from once to multiple times per week, significantly slowed the rate of cognitive decline. Rather than focusing on exercise duration, the research emphasized the consistency and frequency of activity over time.

“The improvement of the decline rate may seem modest, but it builds up over time,” Song explained. “If this slower decline continues, it could potentially delay the onset of dementia by many years, giving people more time to live independently and maintain quality of life.”

Reference: Song, S., Sung, M. H., Diaz, D., Lin, Z., Tate, A. D., Chen, Z., ... & Jin, Y. Long-term cumulative physical activity associated with less cognitive decline: Evidence from a 16-year cohort study. The journal of prevention of Alzheimer's disease, 100194.

Researchers Reveal Better Way to Measure Health Than BMI

A new study from the University of Florida Health, published in the Annals of Family Medicine, challenges the long-standing use of body mass index (BMI) as a key indicator of health risk. The findings show that BMI is a poor predictor of long-term mortality, and suggest that a more direct measure of body fat bioelectrical impedance analysis offers a significantly better assessment of health risk.

BMI does not differentiate between muscle and fat, limiting its accuracy as an indicator of actual body composition. To assess its validity, researchers compared BMI with direct measurements of body fat.

The study analyzed data from 4,252 adults who participated in the National Health and Nutrition Examination Survey and were tracked for 15 years through the national death index. Researchers used bioelectrical impedance analysis, a method that gauges body fat by measuring the resistance of body tissues to a small electrical current a technology that is increasingly available in clinical settings.

The results were striking. Individuals with high body fat levels as measured by impedance analysis were 78% more likely to die of any cause, and about 3.5 times more likely to die from heart disease, compared to those with healthy body fat levels. BMI, by contrast, showed no statistically significant association with mortality from any cause.

Senior author Dr. Frank Orlando medical director of UF Health Family Medicine – Springhill, said BMI’s use as a “vital sign” of health isn’t supported by good evidence. “One of the routine measures we take alongside traditional vital signs is BMI. We use BMI to sort of screen for a person having an issue with their body composition, but it’s not accurate for everyone like vital signs are,” he added.

The authors call for a shift in clinical practice, urging the medical community to replace BMI with more accurate tools to evaluate body composition and health risk.

Reference: Body Mass Index vs Body Fat Percentage as a Predictor of Mortality in Adults Aged 20-49 Years

Arch G. Mainous, Lu Yin, Velyn Wu, Pooja Sharma, Breana M. Jenkins, Aaron A. Saguil, Danielle S. Nelson, Frank A. Orlando

The Annals of Family Medicine Jun 2025, 240330; DOI: 10.1370/afm.240330

Even Low Nitrate Levels in Drinking Water May Be Linked to Preterm Birth, Low Birth Weight

Even minimal levels of nitrate contamination in drinking water far below the current regulatory threshold may pose significant risks to unborn children, according to a new study published in PLOS Water. The research, led by Jason Semprini of Des Moines University College of Health Sciences, suggests that existing safety standards may not adequately protect pregnant women and their babies.

Nitrate is a naturally occurring compound commonly used in fertilizers, often seeping into groundwater through agricultural runoff. While the U.S. Environmental Protection Agency (EPA) has capped the acceptable nitrate level in drinking water at 10 milligrams per liter (mg/L) since 1992, Semprini's analysis indicates potential health effects at levels well below that limit.

Using a dataset of 357,741 birth records in Iowa from 1970 to 1988, Semprini linked county-level nitrate measurements to early pregnancy periods specifically within 30 days of conception. During the study period, nitrate exposure in drinking water increased by an average of 8% annually, with a mean concentration of 4.2 mg/L.

After adjusting for parental and seasonal variables, the study found that nitrate exposure of just 0.1 mg/L a mere 1% of the EPA’s current limit was associated with an increased risk of preterm birth. Exposure above 5 mg/L was also linked to low birthweight. Interestingly, no additional risks were identified at levels exceeding 10 mg/L, the current regulatory threshold.

“Our work adds to the evidence base that the current regulatory threshold (>10mg/L) may be insufficient for protecting the in utero transmission of water-based nitrate during the first trimester of pregnancy,” said Semprini. He emphasized that “there is no safe level of prenatal nitrate exposure,” and drew a striking comparison: “The estimated impact from prenatal exposure to nitrates reflects 15% of the harm from prenatal exposure to smoking cigarettes.”

With rising nitrate levels in groundwater and outdated standards in place, the study underscores the urgent need to reevaluate national water quality regulations.

Reference: Semprini J (2025) Early prenatal nitrate exposure and birth outcomes: A study of Iowa’s public drinking water (1970–1988). PLOS Water 4(6): e0000329. https://doi.org/10.1371/journal.pwat.0000329