A rare genetic mutation, never seen before, protected a man with an inherited form of Alzheimer’s from developing the disease for decades. He is the second person found to have such protection, following a report in 2019 of a woman with a different mutation. Both mutations may have staved off the disease for years by acting in similar ways in the brain, an insight that could lead to new treatments for all forms of Alzheimer’s, researchers report. Both the man and woman were members of a Colombian family who have a mutation in the PSEN1 gene that causes the rare inherited variety of Alzheimer’s. People with “familial” Alzheimer’s usually start showing signs in their 40s. The woman stayed sharp into her 70s, while the man described in the new study was still mentally healthy at 67. “That means they were protected, because they should have gotten the disease 30 years earlier, and they didn’t,” says neurologist Diego Sepulveda-Falla. Amyloid plaques, thought by many researchers to be deeply involved in Alzheimer’s, were abundant in both patients’ brains. But the woman had low levels of another possible culprit, clusters of proteins called tau tangles (orange clumps in this illustration). Surprisingly, the man “was severely affected by tau,” Sepulveda-Falla says. But some key regions had been spared from tau buildup. (🎨: Juan Gaertner/Science Photo Library/Getty Images Plus) #science #alzheimers #neuroscience #disease #dementia #genetic #mutation

In a two-star system about 160,000 light-years away from Earth in the Large Magellanic Cloud, the larger star is stretched and pulled by its companion’s gravity as shown in the illustration. That gravitational tug-of-war causes the star’s brightness to change drastically and rhythmically. Now, a computer simulation suggests that this steady heartbeat of starlight is caused by giant tidal waves undulating and breaking on the star’s surface. Waves would occur about once a month, as the two stars orbit each other and pass near enough that gravitational forces raise tides on both stars’ surfaces, scientists suspect based on the simulation (see second image), much the way the moon tugs on Earth’s oceans. On the stars, though, that tug would be substantially more extreme. The larger star is around 35 times the mass of the sun. The smaller one is around 10 solar masses. And the waves may reach up to 3.3 million kilometers tall or three times the sun’s diameter. (🎨, first illustration: Melissa Weiss/CFA, 📸, second image: M. Macleod and A. Loeb/Nature Astronomy 2023 ) #space #stars #astronomy #gravity #physics