Chemotherapy’s gut damage turns out to have a surprising upside. By changing nutrient availability in the intestine, it alters gut bacteria and increases levels of a microbial molecule that travels to the bone marrow. This signal reshapes immune cell production, strengthening anti-cancer defenses and making metastatic sites harder for tumors to colonize. Patient data suggest this immune rewiring is linked to better survival.

Alzheimer’s may be driven far more by genetics than previously thought, with one gene playing an outsized role. Researchers found that up to nine in ten cases could be linked to the APOE gene — even including a common version once considered neutral. The discovery reshapes how scientists think about risk and prevention. It also highlights a major opportunity for new treatments aimed at a single biological pathway.

In Guatemala’s Western Highlands, researchers found that the drinking water people trust most may actually be the riskiest. Bottled water from refillable jugs—seen as the safest choice—was frequently contaminated with harmful bacteria, while protected municipal wells were the cleanest.

New research suggests that auditory hallucinations in schizophrenia may come from a brain glitch that confuses inner thoughts for external voices. Normally, the brain predicts the sound of its own inner speech and tones down its response. But in people hearing voices, brain activity ramps up instead, as if the voice belongs to someone else. The discovery could help scientists develop early warning signs for psychosis.

Researchers have identified a promising new weapon against triple-negative breast cancer, one of the most aggressive forms of the disease. An experimental antibody targets a protein that fuels tumor growth and shuts down immune defenses, effectively turning the immune system back on. In early tests, the treatment slowed tumor growth, reduced lung metastases, and destroyed chemotherapy-resistant cancer cells.