Medical Bulletin 19/December/2025

Dementia, including Alzheimer’s disease and vascular dementia, affects millions worldwide, and experts have long looked for dietary factors that could prevent age related cognitive decline. To explore dairy’s role, researchers from Lund University analyzed detailed diet questionnaires and health outcomes across participants who remained dementia free at the study’s start. Over 25 years, they tracked how different types of dairy products—high fat cheese, cream, milk, butter, and their low fat versions—related to dementia risk.

The findings were striking. Those who consumed at least 50 grams (about one third cup) of high fat cheese daily or 20 grams (about 1.5 tablespoons) of high fat cream had a significantly lower risk of both overall and vascular dementia. In contrast, low fat dairy, milk, and butter showed no association with reduced risk. According to senior author Dr. Emily Sonestedt, the difference may lie in how these foods are produced and used. “Cheese is fermented, producing bioactive compounds that can reduce inflammation and improve blood vessel function,” she explained. “Cream is usually part of cooked meals, while milk’s consumption patterns vary more widely.”

Genetic factors also played a role. Roughly 15–20% of participants carried the APOE ε4 gene, which increases Alzheimer’s risk—and these individuals did not experience any protective benefits from dairy. This suggests that diet may interact differently with genetic backgrounds, reinforcing the need for personalized brain health advice.

The authors stress that the study is observational, meaning it cannot prove cause and effect. “This isn’t a green light to load up on cheese,” Sonestedt noted. “But it does show that, in moderate amounts, full fat dairy—especially fermented kinds—fits comfortably within a healthy, balanced diet.”

REFERENCE: Du, Y., et al. (2025). High- and Low-Fat Dairy Consumption and Long-Term Risk of Dementia. Neurology. doi: 10.1212/wnl.0000000000214343. https://www.neurology.org/doi/10.1212/WNL.0000000000214343

Study reveals how gut microbes help ensure healthy, successful pregnancy

A healthy pregnancy may depend as much on the gut as it does on the womb. A new study from Weill Cornell Medicine, published in Cell, reveals that gut microbes help train a mother’s immune system to tolerate her developing fetus, preventing inflammation that can otherwise trigger miscarriages. The research provides compelling evidence that microbial metabolites—tiny molecules made by bacteria—play an active role in maintaining maternal fetal harmony.

Pregnancy poses a unique challenge to the body’s immune system. The mother must protect herself from infections while also tolerating the semi foreign fetus. When this balance breaks down, immune cells can attack fetal tissues, leading to pregnancy loss. According to senior author Dr. Melody Zeng, the team wanted to uncover whether gut bacteria might influence this immune adaptation—given their known effects on inflammation and immune regulation.

To explore this, researchers used two mouse models: one completely germ free (raised in sterile conditions without bacteria, viruses, or fungi) and another treated with broad spectrum antibiotics to disrupt the microbiome. Compared with pregnant mice with healthy gut bacteria, these germ free and antibiotic treated mice showed excessive placental inflammation and up to 50 percent fetal loss. Their immune systems overproduced inflammatory T cells and antibodies that mistakenly targeted fetal tissues.

By contrast, mice with an intact microbiome had abundant myeloid derived suppressor cells (MDSCs) and RORγt⁺ regulatory T cells (pTregs)—immune cells that foster tolerance toward the fetus. The researchers traced these protective effects to tryptophan derived metabolites in the maternal bloodstream, produced by beneficial gut bacteria. When germ free mice were given these metabolites or the bacteria that make them, fetal survival increased from 50 to 95 percent. Administering unrelated bacteria had no such effect, confirming the specificity of this mechanism.

Corroborating evidence came from human tissue samples. Women who had experienced recurrent miscarriages showed lower levels of tryptophan metabolites and fewer tolerance inducing immune cells in uterine tissue, mirroring the mouse findings.

The study points toward a new frontier in reproductive medicine—targeting the gut microbiome to support healthy pregnancies. “Our research shows that certain gut bacteria help the immune system learn to see the fetus as safe,” said Dr. Zeng. The team now plans to explore microbial or metabolite based therapies that could help women facing infertility or unexplained pregnancy loss, bringing the concept of “gut to womb communication” into clinical focus.

REFERENCE: Brown, J. A., et al. (2025). Gut microbiota promotes immune tolerance at the maternal-fetal interface. Cell. doi: 10.1016/j.cell.2025.11.022. https://www.cell.com/cell/abstract/S0092-8674(25)01318-2

Stress identified as possible link between depression and heart disease risk

Stress doesn’t just weigh on your mind—it can strain your heart too. A large new study from Mass General Brigham has found that people with depression and anxiety face a higher risk of cardiovascular disease, and that this connection appears to be driven by stress-related brain activity, nervous system imbalance, and chronic inflammation. Published in Circulation: Cardiovascular Imaging, the findings highlight how emotional distress can biologically “get under the skin,” influencing the body’s cardiovascular system in measurable ways.

Depression and anxiety are two of the most common mental health conditions worldwide, and both have long been linked to higher rates of heart attack, heart failure, and stroke. To better understand why, researchers analyzed medical and behavioral data from 85,551 adults enrolled in the Mass General Brigham Biobank. Among them, 14,934 had both depression and anxiety, 15,819 had one, and 54,798 had neither. Participants were tracked for a median of 3.4 years, during which 3,078 experienced major cardiovascular events.

The analysis revealed a clear pattern: individuals with depression or anxiety had a higher risk of cardiovascular disease, but those with both conditions faced about a 32% greater risk than patients with only one. These differences remained significant even after accounting for lifestyle factors such as smoking, exercise, diet, and medical conditions like diabetes or hypertension.

To probe deeper, the researchers studied advanced brain imaging and biomarkers of stress in a subset of participants. Those with depression or anxiety showed heightened activity in the amygdala—the brain’s stress center—alongside lower heart rate variability (indicating an overactive “fight-or-flight” response) and elevated blood levels of C-reactive protein (CRP), a marker of inflammation. Together, these changes form a biological chain: ongoing stress overactivates the nervous system, raises blood pressure and heart rate, and fuels inflammation—all of which damage blood vessels over time.

“This research shows that managing your emotional health is managing your heart health,” said Dr. Shady Abohashem, lead author of the study. The team is now testing whether stress reduction therapies, anti inflammatory drugs, or lifestyle interventions can help normalize these biological signals and, ultimately, protect the heart.

For patients, the message is simple but powerful: caring for your mind could be one of the best things you do for your heart.

REFERENCE: Abohashem, S., et al. (2025) Depression and Anxiety Associate with Adverse Cardiovascular Events via Neural, Autonomic and Inflammatory Pathways. Circulation: Cardiovascular Imaging. DOI: 10.1161/CIRCIMAGING.124.017706. https://www.ahajournals.org/doi/10.1161/CIRCIMAGING.124.017706