Science
Aging Women’s Brain Mysteries Are Tested in Trio of Studies
Women’s brains are superior to men’s in at least in one respect — they age more slowly. And now, a group of researchers reports that they have found a gene in mice that rejuvenates female brains.
Humans have the same gene. The discovery suggests a possible way to help both women and men avoid cognitive declines in advanced age.
The study was published Wednesday in the journal Science Advances. The journal also published two other studies on women’s brains, one on the effect of hormone therapy on the brain and another on how age at the onset of menopause shapes the risk of getting Alzheimer’s disease.
A gene that slows brain aging
The evidence that women’s brains age more slowly than men’s seemed compelling.
Researchers, looking at the way the brain uses blood sugar, had already found that the brains of aging women are years younger, in metabolic terms, than the brains of aging men.
Other scientists, examining markings on DNA, found that female brains are a year or so younger than male brains.
And careful cognitive studies of healthy older people found that women had better memories and cognitive function than men of the same age.
Dr. Dena Dubal, a professor of neurology at the University of California, San Francisco, set out to understand why.
“We really wanted to know what could underlie this female resilience,” Dr. Dubal said. So she and her colleagues focused on the one factor that differentiates females and males: the X chromosome. Females have two X chromosomes; males have one X and one Y chromosome.
Early in pregnancy, one of the X chromosomes in females shuts down and its genes go nearly silent. But that silencing changes in aging, Dr. Dubal found.
She and her colleagues looked in the hippocampus, the brain’s center of memory and cognition, which deteriorates as one ages and is ravaged by Alzheimer’s.
When looking at aging hippocampuses, “we were astounded to find that genes woke up,” Dr. Dubal said, referring to the silent X chromosomes. The study was done in aging mice, but the researchers believe the finding is applicable to humans because mice show the same age-related effects on brain functioning, with females performing better than males.
Her group focused on one particular awakened gene, Plp1. It makes a protein that is part of myelin, a fatty sheath around nerve cells that “allows information to flow back and forth, like a highway,” Dr. Dubal said.
What would happen, she asked, if she used gene therapy to give aging male mice a dose of Plp1 in their hippocampuses?
Her team found that the mice regained memory and cognition. They did not even have to give the gene to many cells, Dr. Dubal added. “Just a little boost went a long way,” she said.
Then she gave the gene therapy to female mice, although they were already making Plp1. Their memories and cognition got even better.
“I’m so excited about this,” Dr. Dubal said. “Even an old brain can become more youthful and function better.”
Alzheimer’s and hormone therapy
Millions of women use hormone therapy to relieve symptoms of menopause like hot flashes and vaginal dryness, but there remains a concern about how it might affect the brain.
The issue was raised when a large and rigorous federal study, the Women’s Health Initiative, published in 2003, concluded that Prempro, a popular hormone treatment at the time, doubled the risk of dementia.
Since then, other scientists have argued that the risk depends on when a woman takes hormones. If she takes them within 10 years of menopause, they say, her brain will be fine. Current treatment guidelines reflect that view.
To examine what happens inside the brain after hormone therapy, Rachel F. Buckley, a neuroscientist at Massachusetts General Hospital, and her colleagues recruited 146 healthy women aged 51 to 89. They scanned the women’s brains for tau, a protein that accumulates in the brains of people with Alzheimer’s.
The investigators knew only the ages of the women, and whether they had ever taken hormone therapy. To Dr. Buckley’s surprise, they saw an effect.
The women over 70 who had received hormone therapy had a greater accumulation of tau than the women who had never had it. Having more tau did not mean the women had Alzheimer’s, but it could have put them on the path toward the disease.
Women under 70 in the study did not have more tau in their brains. But, the researchers said, they did not know if younger women who took hormones would have more tau later in life.
The study was observational, meaning it cannot prove cause and effect. The women with more tau might have been different in other ways that the researchers did not account for, which has left uncertainty about the finding.
Dr. Buckley, asked what advice she would give women about hormone therapy and the risk of Alzheimer’s, said “talk to your doctor,” acknowledging that it was not a satisfactory answer.
Age of menopause and Alzheimer’s
Another study published on Wednesday used clinical records and autopsy data to compare the brains of 268 women. Some started menopause early, around age 45, while the rest started at the more typical age of around 50.
The researchers who led the study reported that age at the start of menopause had no effect on cognitive decline, the integrity of brain synapses or on brain markers of Alzheimer’s.
The results, said Madeline Wood Alexander, the study’s lead author and a doctoral student at Sunnybrook Research Institute in Toronto, were “not what we expected.” The researchers thought the women who started menopause earlier would have worse brain functioning. That is because levels of estrogen, which can protect neurons, plummet at menopause, the authors said.
The researchers did identify one correlation that they emphasized as their main finding: The synapses of women who begin menopause earlier may become more vulnerable to changes linked to Alzheimer’s as they naturally deteriorate.
They reported that they did not see that effect in women with early menopause who used hormone therapy.
The result clashes with those of the other study, which indicated hormone therapy might increase the risk of Alzheimer’s-like changes in the brain. There was no clear explanation for the seemingly contradictory findings.
But experts not involved with either study questioned the conclusions about early menopause and hormone therapy. They said they were not convinced by the statistical analyses and modeling that led to this correlation.
Dr. Deborah Grady, emeritus professor of epidemiology and biostatistics at the University of California, San Francisco, said it was difficult to interpret studies that looked at things like the vulnerability of synapses. If menopause timing had an effect, she said, she’d like to see it show up in the actual incidence of Alzheimer’s in these women.
Dr. Jacques Rossouw, who was a program officer for the Women’s Health Initiative, had a similar concern. He added that the authors did so many statistical tests that it was possible the correlation they found occurred by chance.
And even if it is real, he said, “this can’t be a big effect if there was no effect of age of menopause on Alzheimer’s pathology.”
Science
A renewed threat to JPL as the Trump administration tries again to cut NASA
WASHINGTON — NASA recaptured the world’s attention with Artemis II, which took astronauts to the moon and back for the first time in half a century. But the agency’s scientific projects could again be under threat as the Trump administration makes a renewed push to drastically cut their funding — including at the Jet Propulsion Laboratory.
The cuts, proposed in the Trump administration’s 2027 budget request to Congress, would pose further challenges to the already weakened Caltech-managed lab and could be broadly damaging to American efforts to bring back new discoveries from space. They echo last year’s attempt by the administration to slash NASA funding, which Congress rejected.
Though the Artemis project is billed as laying a foundation for a crewed NASA mission to Mars, exploration of the Red Planet is among the endeavors that could be slashed. The rover currently exploring Mars’ ancient river delta and a mission to orbit Venus are among projects with JPL involvement targeted for spending cuts, according to an analysis of the NASA budget proposal by the nonprofit Planetary Society.
“This isn’t [because] they’re not producing good science anymore. There’s no rhyme or reason to it,” said Casey Dreier, chief of space policy at the Planetary Society, which led opposition to the administration’s similar effort to cut NASA funding last year.
Storm clouds hang over the Jet Propulsion Laboratory on Feb. 7, 2024.
(David McNew / Getty Images)
This time, the administration is asking Congress to cut NASA funding by 23% — including a 46% cut to its science programs, which are responsible for developing spacecraft, sending them into outer space to observe and analyzing the data they send back.
The proposal would cancel 53 science missions and reduce funding for others, according to the Planetary Society analysis. The effort to pare down NASA Science comes amid the Trump administration’s broader effort to cut scientific research across federal agencies.
The plan swiftly drew bipartisan criticism from members of Congress, who rejected the administration’s similar 2026 proposal in January. Republican Sen. Jerry Moran of Kansas, who chairs the Senate appropriations subcommittee that oversees NASA, indicated last week that he would work to fund NASA similarly for 2027, saying it would be “a mistake” not to fund science missions.
Moran plans to hold a hearing with NASA Administrator Jared Isaacman before the end of April to review the budget request, a spokesperson for his office said. The president’s budget request is an ask to Congress, which ultimately holds the power to allocate funding.
But until Congress creates its own budget, NASA will use the plan as its road map, which could slow grants and contracts. The proposal “still creates enormous chaos and uncertainty in the meantime for critical missions, the scientific workforce, and long-term research planning,” said Rep. Judy Chu (D-Monterey Park), whose district includes JPL.
A NASA spokesperson declined to comment Friday. In the budget request, Isaacman wrote that NASA was “pursuing a focused and right-sized portfolio” for its space science missions in order to align with Trump’s federal cost-cutting goals.
The budget “reinforces U.S. leadership in space science through groundbreaking missions, completed research, and next-generation observatories,” Isaacman wrote.
Jared Isaacman testifies during his confirmation hearing to be the NASA administrator in the Russell Senate Office Building on Capitol Hill on Dec. 3, 2025.
(Anna Moneymaker / Getty Images)
At JPL — which has for decades led innovation in space science and technology from its La Cañada Flintridge campus — questions had already swirled about the lab’s role in the future of NASA work.
Multiple rounds of layoffs over the last two years, the defunding of its embattled Mars Sample Return mission and a shift by the Trump administration toward lunar exploration and away from the type of scientific work that JPL executes had pushed the lab into a challenging stretch.
It has had a steady stream of employee departures in recent months, and those left have been scrambling to court outside funding from private investors, sell JPL technology to companies and increase productivity in hopes of keeping the lab afloat, according to two former staffers, who requested anonymity to describe the mood inside the lab.
“If we’re not doing science, then what are we doing?” asked one former employee, who recently left JPL after more than a decade there.
A spokesperson for the lab declined to comment, referring The Times to the budget proposal.
The NASA programs marked for cancellation or cutbacks support thousands of jobs at JPL and other centers, said Chu, who has led a push for increased funding for NASA Science. After last year’s layoffs, JPL “cannot afford to lose more of this expertise,” she said in a statement.
Among the JPL projects that appear to be slated for cancellation are two involving Venus, Dreier said. One, Veritas, is early in development and would give work to the lab for the next several years, he said.
The project would be the first U.S. mission to Venus in more than 30 years, Dreier said, and aims to make a high-resolution mapping of the planet’s surface and observe its atmosphere.
The Perseverance rover, which is on Mars collecting rock and soil samples, could face spending reductions. The budget request proposes pulling some funding from Perseverance to fund other planetary science missions and reducing “the pace of operations” for the rover.
Though how the Mars samples might get back to Earth is uncertain, the rover is still being used to explore the planet and search for evidence of whether it could have ever been habitable to life.
Researchers hope the tubes of Martian rock, soil and sediment can eventually be brought back to Earth for study. The team has about a half a dozen more sample tubes to fill and the rover is in good shape, said Jim Bell, a planetary scientist and Arizona State University professor who leads the camera team on Perseverance, which works daily with JPL.
He said NASA’s spending proposal put forth “no plan” for the future of the agency’s work.
“Are people just supposed to walk away from their consoles,” Bell asked, “and let these orbiters around other planets or rovers on other worlds — just let them die?”
The NASA document did not clearly show which programs were targeted for cuts and did not list which projects were targeted for cancellation. The Planetary Society and the American Astronomical Society each analyzed the proposal and found that dozens of projects appeared to be canceled without being named in the document.
Across NASA, other projects slated for cancellation according to the Planetary Society’s analysis include New Horizons, a spacecraft exploring the outer edge of the solar system; the Atmosphere Observing System, a planned project to collect weather, air quality and climate data; and Juno, a spacecraft studying Jupiter.
The administration’s plan also doesn’t prioritize new scientific projects, Bell said, which further jeopardizes long-term job stability and space discovery at centers like JPL.
“We’re going through this long stretch now with very few opportunities to build these spacecrafts,” Bell said. “All of the NASA centers are suffering from the lack of opportunities.”
Last year, the Trump administration proposed to slash NASA’s 2026 funding by nearly half. Instead, Congress approved funding in January that provided $24.4 billion for the agency — a cut of about 29% rather than the proposed 46%. The 2027 budget request asks for $18.8 billion.
Congress kept funding for science missions nearly steady, allocating $7.25 billion for science missions, about a 1% decrease from 2025. The administration had proposed cutting the science investment down to $3.91 billion. This time, the budget requests $3.89 billion.
Under the Trump administration, NASA has put an emphasis on moon exploration, including this month’s successful Artemis II mission. Isaacman, who defended the proposed cuts on CNN last week, touted the agency’s lunar plans, including a project to build a base on the moon.
The agency has indicated commitment to some existing science missions, including the James Webb Space Telescope, the to-be-launched Nancy Grace Roman Space Telescope, the Dragonfly spacecraft set to launch for Saturn’s moon in 2028, and other projects.
“NASA doesn’t have a topline problem, we just need to focus on executing and delivering world-changing outcomes,” Isaacman said on CNN.
Scientists have urged the government not to choose between funding science and exploration but to keep up investment in both.
“It’s ultimately kind of confusing, especially on the heels of the Artemis II mission,” said Roohi Dalal, deputy director for public policy at the American Astronomical Society. “The scientific community … is providing critical services to ensure that the astronauts are able to carry out their mission safely, and yet at the same time, they’re facing this significant cut.”
Science
What to plant (and what to remove) in California’s new ‘Zone Zero’ fire-safety proposal
After years of heated debates among fire officials, scientists and local advocates, California’s Board of Forestry and Fire Protection released new proposed landscaping rules for fire-prone areas Friday that outline what residents can and can’t do within the first 5 feet of their homes.
Many of these proposed rules — designed to reduce the risk of a home burning down amid a wildfire — have wide support (or at least acceptance); however, the most contentious by far has been whether the state would allow healthy plants in the zone.
Many fire officials and safety advocates have essentially argued anything that can burn, will burn and have supported removing virtually anything capable of combustion from this zone within 5 feet of houses, dubbed “Zone Zero.” They point to the string of devastating urban wildfires in recent years as reason to move quickly.
Yet, researchers who study the array of benefits shade and extra foliage can bring to neighborhoods — and local advocates who are worried about the money and labor needed to comply with the regulations — have argued that this approach goes beyond what current science shows is effective. They have, instead, generally been in favor of allowing green, healthy plants within the zone.
The new draft regulations attempt to bridge the gap. They outline more stringent requirements to remove all plants in a new “Safety Zone” within a foot of the house and within a bigger buffer around potential vulnerabilities in a home’s wildfire armor, including windows that can shatter in extreme heat and wooden decks that can easily burst into flames. Everywhere else, the rules would allow residents to maintain some plants, although still with significant restrictions.
The rules generally do not require the removal of healthy trees — instead, they require giving these trees routine haircuts.
Once the state adopts a final version of the rules, homeowners would have three years to get their landscaping in order and up to five years for the bigger asks, including removing all vegetation from the Safety Zone and updating combustible fencing and sheds within 5 feet of the home. New constructions would have to comply immediately.
The rules only apply to areas with notable fire hazard, including urban areas that Cal Fire has determined have “very high” fire hazard and rural wildlands.
Officials with the Board will meet in Calabasas on Thursday from 1 p.m. to 7 p.m. to discuss the new proposal and hear from residents.
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Some L.A. residents are championing a proposed fire-safety rule, referred to as “Zone Zero,” requiring the clearance of flammable material within the first five feet of homes. Others are skeptical of its value.
Where is the Safety Zone?
The proposed Safety Zone with stricter requirements to remove all vegetation would extend 1 foot from the exterior walls of a house.
In a few areas with heightened vulnerabilities to wildfires, it extends further.
The Safety Zone covers any land under the overhang of roofs. If the overhang extends 3 feet, so does the Safety Zone in that area. It also extends 2 feet out from any windows, doors and vents, as well as 5 feet out from attached decks.
What plants would be allowed in the Safety Zone?
Generally, nothing that can burn can sit in the Safety Zone. This includes mulch, green grass, bushes and flowers.
What plants would be allowed in the rest of Zone Zero?
Homeowners can keep grasses (and other ground-covers, like moss) in this area, as long as it’s trimmed down to no taller than 3 inches.
The rules also allow small plants — from begonias to succulents — up to 18 inches tall as long as they are spaced out in groups. Residents can also keep spaced-out potted plants under this height, as long as they’re easily movable.
What about fences, trees and gates?
Any sheds or other outbuildings would need noncombustible exterior walls and roofs in Zone Zero — Safety Zone or not.
Residents would have to replace the first five feet of any combustible fencing or gates attached to their house with something made out of a noncombustible material, such as metal.
Trees generally would be allowed in Zone Zero. Homeowners would need to keep any branches one foot away from the walls, five feet above the roof and 10 feet from chimneys.
Residents would also have to remove any branches from the lower third of the tree (or up to 6 feet, whichever is shorter) to prevent fires on the ground from climbing into the canopy.
Some trees with trunks directly up against a house in this 1-foot buffer or under the roof’s overhang might need to go — since keeping branches away from the home could prove difficult (or impossible).
However, the board stressed it wants to avoid the removal of trees whenever feasible and encouraged homeowners to work with their local fire department’s inspectors to find case-by-case solutions.
What’s new and what’s not
Some of the rules discussed in Zone Zero are not new — they’ve been on the books for years, classified as requirements for Zone One, extending 30 feet from the home with generally less strict rules, and Zone Two, extending 100 feet from the house with the least strict rules.
For example, homeowners are already required to remove any dead or dying grasses, plants and trees. They also have to remove leaves, twigs and needles from gutters, and they already cannot keep exposed firewood in piles next to their house.
Residents are also already required to keep grasses shorter than 4 inches; Zone Zero lowers this by an inch.
Science
Video: Rescuers Mount a Likely Final Push to Save a Stranded Whale
new video loaded: Rescuers Mount a Likely Final Push to Save a Stranded Whale
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