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Older People Seeking Care for Cannabis Use at Greater Risk for Dementia, Study Finds

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Older People Seeking Care for Cannabis Use at Greater Risk for Dementia, Study Finds

Middle-aged and older adults who sought hospital or emergency room care because of cannabis use were almost twice as likely to develop dementia over the next five years, compared with similar people in the general population, a large Canadian study reported on Monday.

When compared with adults who sought care for other reasons, the risk of developing dementia was still 23 percent higher among users of cannabis, the study also found.

The study included the medical records of six million people in Ontario from 2008 to 2021. The authors accounted for health and sociodemographic differences between comparison groups, some of which play a role in cognitive decline.

The data do not reveal how much cannabis the subjects had been using, and the study does not prove that regular or heavy cannabis use plays a causal role in dementia.

But the finding does raise serious concerns that require further exploration, said Dr. Daniel T. Myran, the first author of the study, which was published in JAMA Neurology.

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“Figuring out whether or not cannabis use or heavy regular chronic use causes dementia is a challenging and complicated question that you don’t answer in one study,” said Dr. Myran, an assistant professor of family medicine at University of Ottawa.

“This contributes to the literature and to a sign, or signal, of concern.”

Dr. Myran’s previous research has found that patients with cannabis use disorder died at almost three times the rate of individuals without the disorder over a five-year period. He has also reported that more cases of schizophrenia and psychosis in Canada have been linked to cannabis use disorder since the drug was legalized.

The latest study, focusing on dementia, adds to a growing body of literature on regular or heavy cannabis use and cognition. Researchers have reported impacts on verbal learning, memory and attention, while imaging studies have pointed to changes in the brain related to the use of cannabis and other substances.

Veterans with traumatic brain injuries in addition to cannabis use disorder may be at heightened risk for early-onset dementia, researchers reported last year.

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But many of the studies are relatively small. The new report’s strength was its large sample and the ability to track patients over time who did not have a diagnosis of dementia when they entered the study, said Madeline Meier, an associate professor of psychology at Arizona State University, who was not involved in the study.

“They were able to rule out dementia at the time of the first cannabis visit, and were able to show the temporal order — the cannabis came first, and the dementia came second,” said Dr. Meier.

Her research, which has followed and periodically tested a cohort of over 1,000 individuals over a period of many years, has linked cannabis use and neuropsychological decline.

“I think you want to combat this whole idea that cannabis is harmless and maybe even has some medical benefits,” Dr. Meier said. “This study is showing an association that I think people should take seriously and say, ‘Maybe this is putting me at risk.’”

She noted that the work by Dr. Myran and his colleagues also found that people seeking care for alcohol use were even more likely to receive a dementia diagnosis than were cannabis users.

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“I’m worried about the substance abuse in that Baby Boomer age,” she said.

More and more people, including seniors, are using cannabis. Medical visits related to cannabis increased more than fivefold among adults 45 and older between 2008 and 2021, the new study found. Among adults 65 and over, visits increased almost 27-fold.

The study included more than 6 million people age 45 and over who did not have a diagnosis of dementia at the start of the research. Of them, 16,275 had an acute-care medical encounter because of cannabis.

The patients with cannabis-related visits were compared to the matched general population, and in a separate comparison, to 140,824 matched patients who needed medical care for all other reasons.

Within five years, 5 percent of those with acute care cannabis visits received a dementia diagnosis. The figure for individuals needing care for other reasons was 3.6 percent, and for similar individuals in the general population, 1.3 percent.

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But people who are heavy cannabis users differ from those who are not in a variety of ways, some of which may help explain the increased risk for dementia, Dr. Myran explained.

While some of the factors can be accounted for, he said, “you can’t control for all of them.”

Another unknown is self-medication, he said. Someone who has started experiencing symptoms of cognitive decline may be more likely to turn to cannabis. If so, then “it looks as if the cannabis is causing dementia, but it’s just on the pathway — they were already developing dementia,” Dr. Myran said.

After making adjustments for age, sex, income and other factors, including other health conditions, he and his colleagues determined that patients who sought care for cannabis-related reasons were 1.23 times as likely as those who had gotten any kind of acute care to be diagnosed with dementia, and 1.72 times as likely as those in the healthier general population.

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China Launches Reusable Rocket in Race With SpaceX

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Video released by Chinese state media shows a state-owned aerospace company launching a rocket and recovering part of it on Friday. The successful launch of a reusable rocket was a major step for China toward challenging SpaceX’s satellite internet dominance.

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Nobel Prize winner leaving UC Berkeley for new role in China

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Nobel Prize winner leaving UC Berkeley for new role in China

Nobel Prize recipient Omar Yaghi is leaving his role at UC Berkeley to lead the development of a new artificial intelligence institute at Tsinghua University in Beijing, the Chinese university announced.

Yaghi will head the AI Chemistry and Materials Research Institute at Tsinghua, where he was appointed an honorary professor in 2022. Known as AIMATRY (AI × Materials × Chemistry), the new center will focus on material design and synthesis through artificial intelligence, according to a statement from the university.

In 2025, Yaghi shared the Nobel Prize in chemistry with Susumu Kitagawa of Kyoto University and Richard Robson of the University of Melbourne for their development of metal-organic frameworks, a type of super-porous material in which metal ions and carbon-based molecules combine to form crystals with exceptionally large surface areas.

The material has the potential to combat climate change by capturing and storing carbon or other pollutants, and by extracting water from the atmosphere in water-scarce areas. Upon awarding the prize, a member of the Nobel committee likened the technology’s ability to store enormous amounts of stuff in seemingly compact spaces to Hermione Granger’s enchanted handbag in the Harry Potter series.

Yaghi’s Irvine-based company, Atoco, has said it will start taking orders later this year for its technology that harvests water from the air.

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A representative for Yaghi said he was not yet available to respond to questions.

China is one of several countries that has been actively recruiting scientists from the U.S., where the Trump administration has slashed science funding, suspended research grants, fired science advisors and tightened immigration restrictions.

“For many, many years, our funding was very competitive; if you worked hard and you were doing good research, you would get funding,” Yaghi said of the U.S. in an interview with Scientific American earlier this year. “The current state is not so encouraging because of the cutting back on grants and support of science by the very agencies that many university researchers rely on.”

Yaghi was born in Jordan to Palestinian refugees, and immigrated to the U.S. when he was 15 to study.

“We’ve learned over and over in human civilization that scholars can move across borders,” Yaghi told the New York Times last year. “This is how knowledge spread and how vast regions of the world lifted themselves out of poverty.”

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Trump administration seeks to limit federal funding that doesn’t ‘advance’ presidential policies

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Trump administration seeks to limit federal funding that doesn’t ‘advance’ presidential policies

A new rule proposed by the White House Office of Management and Budget would fundamentally overhaul the way federal grants are awarded and overseen — a sweeping change that one scientific society said “would all but end the use of scientific merit in the selection of grants and programs across the government.”

Proposed in late May, the rule would give political appointees unprecedented control over federal grants for research, education and infrastructure, and specifies that government funds can only be spent on projects “aligned with administration policies and priorities,” according to a copy of the proposed rule.

The rule would also restrict research topics, limit U.S. scientists’ ability to collaborate with colleagues in other countries and make it easier for the government to suspend or cancel grants at any time.

The changes are intended to improve “transparency, accountability, and oversight for Federal awards” while “ensuring that American tax dollars are not wasted or misused,” according to the White House office.

But critics say that if the rule is implemented, the final sign-off for grants will no longer be in the hands of subject-matter experts within individual agencies, but in those of political appointees.

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“This touches all parts of American life,” said Dr. Eric Rafla-Yuan, a psychiatrist who practices at the Veterans Administration and San Diego County’s psychiatric hospital.

“Control of how all of the federal grants and programs are funded will fall under a small group of highly partisan individuals who would have very few limits on how they spend these billions of taxpayer dollars,” said Rafla-Yuan, who also chairs the Committee to Protect Public Mental Health advocacy group. “This touches everyone’s life, even if they don’t realize it.”

OMB published the proposed rule May 29, opening a 45-day comment period that closes July 13.

Opposition to the proposed rule has mobilized multiple sectors of society. Professional groups representing cancer researchers, civil engineers, county governments, medical schools, housing agencies, city and municipal governments, nonprofits and others have publicly expressed concerns about potential consequences.

By midday Thursday, the Federal Register logged nearly 100,000 comments about the proposal, many of them expressing concern.

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“I understand the need for oversight, fiscal responsibility, and accountability. That is not the issue,” wrote Jack Feldman, a neuroscientist who holds the David Geffen School of Medicine Chair in Neuroscience at UCLA. “The issue is whether scientific research is to be judged by scientific merit, or whether it can be approved, denied, or terminated according to broad political criteria that may change from one administration to the next.”

Crucially, the rule converts policies governing federal grants from “guidance” into binding regulations that all agencies would be required to follow. It would give political appointees power to override federal agencies’ merit-based reviews and mandate that a political appointee review decisions to ensure that all awards “demonstrably advance the President’s policy priorities.”

The elevation of political appointees in what were previously merit-based decisions has alarmed many scientists.

“The proposed rule changes would all but end the use of scientific merit in the selection of grants and programs across the government,” read a statement from the Planetary Society, a nonprofit dedicated to space research.

Researchers and science groups have also expressed concern about a section of the rule prohibiting the promotion of “theories of disparate-impact liability” — a legal concept that refers to policies that appear neutral but cause disproportionate harm to certain groups.

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The section’s vague language and many loopholes could have a chilling effect on any research that studies the effects of a disease, policy or public health intervention on any specific group of people, Rafla-Yuan said.

As an example, he said, “if there’s a specific age range that is at higher risk for suicide, and we want to figure out, well, what’s going on with people that are aged 14 to 19 … we can’t do that under the wording in this rule.”

New restrictions on collaborations with scientists in other countries would hinder opportunities for U.S. researchers and limit innovation, said Joanne Padrón Carney, chief government relations officer for the American Assn. for the Advancement of Science.

“Science is a global enterprise. Especially in biomedical and public health fields, diseases don’t care about borders or government policies,” she said.

California’s congressional delegation sent a letter Wednesday asking OMB to rescind the proposal, outlining concerns about its impact on scientific innovation, U.S. competitiveness and the fiscal stability of local governments, many of which rely on federal grants for local services.

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The proposed rule grants the federal government broad powers to suspend or cancel grants for any reason, introducing “unprecedented unpredictability into local governance,” the lawmakers wrote, “leaving vital infrastructure projects unfinished and abandoning vulnerable populations who rely on these services.”

Republican Sen. Susan Collins has also asked the White House to withdraw certain parts of the letter and extend the public comment period, saying the proposed rule as written would “harm small and rural communities, undermine scientific and biomedical research, and conflict with Congress’ control over the federal funding process.”

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