Monday, May 11, 2026

Beer and cannabis could share ‘sex switch’, UCD-lead study find

University College Dublin

image:
Photo of cannabis plant
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Credit: CCO

Researchers identify genetic “switch” that determines the sex of cannabis plants, and find the same system may exist in hops.

The study, published in New Phytologist, pinpoints a specific section of the X chromosome that influences whether cannabis plants develop as male, female, or both.

“It was known for quite a while that female cannabis plants possess two X chromosomes and male plants carry an X and a Y chromosome, but there are thousands of genes on those chromosomes,” said Associate Professor Rainer Melzer, senior author of the study.

“Which of those genes determines whether a plant becomes male or female was unknown.”

Within a small stretch of DNA, researchers identified three closely linked genes that act together to control both male and female development.

Using genetic mapping, genome sequencing and gene expression analysis, the UCD team, in collaboration with international partners, identified this region, known as Monoecy1, as a major control point for sex expression.

The same key genes were also found in hops, located in a matching region of the X chromosome.

This suggests the genetic “switch” predates the divergence of the two plants around 28 million years ago.

“We were quite surprised when a lot of evidence pointed to a small region on the X chromosome as a key driver of sex determination, because in many other species, including humans, the Y chromosome determines sex,” said Matteo Toscani, a PhD student at UCD and first author of the study.

The findings have practical implications for agriculture, particularly for crops like hops and cannabis where female plants are economically preferred.

In brewing, only female hop plants produce the cones that give beer its aroma and flavour, while in cannabis, female plants are cultivated for cannabinoids such as CBD.

Being able to identify and control plant sex could reduce crop losses and allow growers to reliably produce all-female plants for cannabinoid or hop cone yields, or uniform monoecious crops for fibre production.

The study was funded by Taighde Éireann – Research Ireland and led by researchers at UCD in collaboration with Université Paris-Saclay.

Journal

New Phytologist

DOI

10.1111/nph.71185

Subject of Research

Cells

Article Title

Beer and cannabis could share ‘sex switch’, UCD-lead study finds

Edible cannabis and pain, sleep, and mental health management in older adults

JAMA Network Open

About The Study:

In this qualitative study, older adults were motivated to use cannabis as an alternative approach to address health concerns. These findings highlight the importance of physician awareness of older adults’ motivations and concerns to support informed counseling and resources.

Corresponding Author: To contact the corresponding author, Rebecca K. Delaney, PhD, email rebecca.delaney@hsc.utah.edu.

To access the embargoed study: Visit our For The Media website at this link https://media.jamanetwork.com/

(doi:10.1001/jamanetworkopen.2026.11718)

Editor’s Note: Please see the article for additional information, including other authors, author contributions and affiliations, conflict of interest and financial disclosures, and funding and support.

# # #

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About JAMA Network Open: JAMA Network Open is an online-only open access general medical journal from the JAMA Network. On weekdays, the journal publishes peer-reviewed clinical research and commentary in more than 40 medical and health subject areas. Every article is free online from the day of publication.

Journal

JAMA Network Open

Study reveals why older adults are using cannabis edibles

University of Utah Health

For adults over 60, cannabis use is increasing faster than in any other demographic.

But science has yet to keep up with why older adults are using cannabis products, which products they choose, and how they make decisions about which products to use.

A new study by researchers from University of Utah Health and University of Colorado Boulder reveals that many older adults start cannabis seeking more effective or non-pharmaceutical options to manage sleep, pain, or mental health, and that many people base their decisions on word of mouth rather than discussions with health care providers.

The results are published in JAMA Network Open.

Many seek more effective options to manage common health conditions

The researchers interviewed 169 adults over 60 who were about to purchase cannabis for the first time to identify common motivations.

“Overall, they really wanted better quality of life, reducing their pain, getting better sleep, and being able to enjoy time with family and friends a little bit more,” says Rebecca Delaney, PhD, assistant professor of population health sciences at U of U Health and first author on the study.

“For the most part, we found that these folks aren’t really interested in getting high. They just want to feel better,” adds Angela Bryan, PhD, professor of psychology and neuroscience at CU Boulder and senior author on the study.

Many participants had heard positive anecdotes about product usefulness from friends or family members, which tended to influence decisions. “They brought a lot of feedback from other people to inform their opinions,” Delaney says. “Word of mouth has a really big impact.”

Discussions with medical providers were rarely part of the picture, suggesting that better informational materials for patients and providers could be needed to drive conversations and help people make informed decisions about their health.

To CBD or to THC, that is the question

Older adults also faced the question of which products to use. Edible cannabis products may contain tetrahydrocannabinol (THC, the main psychoactive component of cannabis), cannabidiol (CBD), or both, and it was unclear what motivated and informed their decisions about which to purchase.

Many people perceived CBD-only products as therapeutically beneficial, which was often driven by anecdotal claims. People tended to perceive THC as offering benefits like improving mood. But most people chose combination products containing both, seeing them as a “Goldilocks option” that gives the best of both worlds.

Toward better decision-making

An important caveat is that the survey was conducted in Colorado, where recreational cannabis is legal. For older adults in Utah and other states where only medical use is permitted, the decision-making process may look different. But Delaney suspects that people’s core motivations—using cannabis to attempt to treat chronic pain, poor sleep, or mental health concerns—are probably the same.

Delaney says that the results help show people’s baseline understanding of using cannabis to address health concerns, providing a foundation to develop better informational tools and clinical support.

“The ultimate goal is to develop resources to help people make decisions and find products that meet their needs, and to figure out how we can distill information to patients and physicians,” Delaney says. “We would really love to see more of these conversations happening between physicians and patients to make sure that people feel supported and informed when seeking alternative ways to address their pain.”

###

This research is published in JAMA Network Open as “Edible Cannabis and Pain, Sleep, and Mental Health Management in Older Adults.”

This work was supported by the National Institutes of Health, including the National Institute of Aging (R01AG066698) and the National Center for Advancing Translational Sciences (1K12TR004413) through the Utah Clinical and Translational Science Institute, as well as the American Heart Association (23SCEFIA1154397) and the University of Utah Office of Undergraduate Research. Content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Journal

JAMA Network Open

Method of Research

Survey

Subject of Research

People

Article Title

Edible Cannabis and Pain, Sleep, and Mental Health Management in Older Adults

Article Publication Date

8-May-2026

Psychedelic substances: Who can they help – and who might they harm?

Charité study collates global therapeutic experiences for the first time

Charité - Universitätsmedizin Berlin

Psychedelic substances: Who can they help – and who might they harm? — image:
PD Dr. Felix Betzler, Head of the Recreational Drugs research group at Charité
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Credit: © Charité – Universitätsmedizin Berlin

Psychedelic-assisted therapy is the subject of renewed focus. It involves using psilocybin – a substance found in psychoactive fungi – or LSD to treat mental disorders. Numerous studies are currently underway, with talk rife of a “revolution in psychiatry”. However, doubts also persist. While some patients benefit from this therapy, others do not, and some patients even deteriorate as a result. Scientists led by Charité – Universitätsmedizin Berlin have now collated experiences from therapists around the world in an effort to identify suitable patients more precisely in the future. The researchers have described for the first time the profile of a good candidate for psychedelic-assisted therapy in an article published in Nature Mental Health*.

“Treating patients with psychedelic substances is akin to using a sharp blade. With that in mind, it’s very important to know when to use it – and when not to,” says PD Dr. Felix Betzler, who led the study. Betzler is also Head of the Recreational Drugs research lab at the Department of Psychiatry and Neurosciences on Campus Charité Mitte. There are patients like the middle-aged woman. When she first came to the clinic, she had already been suffering from depression for years.To the point she was no longer able to feel happiness. All medication-based treatment attempts had failed to improve her symptoms, as had years of psychotherapy. She said that her friends, her partner and her dog kept her going. She had been unfit for work for some time. Prior to the therapy, she had no experience with the mind-altering substance psilocybin.

However, she agreed to a session in a controlled study setting. It proved a very intense experience for the patient, who felt her emotions break through. She later described the experience as simultaneously painful and healing, as though she had been sailing through a storm when, suddenly, the sun pierced through the clouds. Six weeks after the treatment, her depression lifted for the first time in over a decade. A recognized depression test identified no measurable signs of the disorder whatsoever.

Intoxicants deployed as therapeutics

The positive effects of both natural and synthetic psychoactive substances have long been known. Psychedelic substances can influence a person’s perception, emotional experiences and state of consciousness, and have a long history of use as intoxicants. Such substances have also been the subject of scientific research for more than 70 years, not least with a view to developing new treatment methods. Hallucinogens such as psilocybin and LSD have yielded success, especially when used to treat severe therapy-resistant depression not alleviated by conventional medications, as well as anxiety disorders, addiction and other mental disorders. It is possible that this exceptional, artificially induced state promotes the formation of new connections between nerve cells, making the brain more “flexible”. The fundamental mechanisms are not yet understood in detail. However, even one or two guided sessions usually achieve a significant impact.

Nevertheless, the treatment outcomes vary significantly, as another example illustrates. Once again, the patient was a middle-aged woman. She received the same diagnosis, had experienced similar symptoms and found herself in similar personal circumstances. Unlike the first patient, however, she experienced the session as a sort of inner torture. There was no breakthrough; she was simply happy once the session was over. Her depression did not lift. Quite the opposite, in fact: after the therapy session, she felt even an even stronger sense of hopelessness, with another straw less to clutch at.

Predicting treatment success

Two seemingly similar patients, yet two treatment outcomes that could hardly be more different. How is this possible? Could demographic or health-related factors that determine treatment success? Might other influences indicate less favorable outcomes, such as severe fear responses, sleep disorders or even a deterioration in depression symptoms? In pursuit of answers, Felix Betzler and his team worked with researchers in Germany, France and the USA to survey therapists around the world who regularly conduct psychedelic-assisted therapies.

In addition to the therapist’s professional experience, therapy approach and therapy context, the comprehensive index of questions developed by the researchers also examined numerous potential characteristics of patients who underwent psychedelic-assisted therapy, including their personal circumstances, aspects of their personality, and the duration and severity of their condition. Their research also scrutinized the therapy setting, the intensity of supervision, and the administered dosage of psychedelic substances. They collected responses from a total of 158 therapists, regardless of whether they worked within a regulated statutory framework – with legal approval based on clinical studies – in countries where the use of these substances is permitted, or whether they provide therapy “underground”, outside the law.

“The most important outcome is the overall patient profile as such because, from a therapist’s perspective, this provides an indication of a good treatment response,” explains Betzler. “We identified a number of pronounced characteristics that the respondents agreed on.” In addition to a stable environment and support from family and friends, certain personality traits also appear conducive to treatment success. “An openness to new experiences, the ability to come to terms with certain circumstances, accept them and let them go, and the ability to form secure attachments are all decisive factors,” says Grace Viljoen, a junior research at the Department of Psychiatry and Neurosciences, and the paper’s lead author. Prior experiences with altered states of consciousness, including through meditation and special breathing techniques, also prove helpful. By contrast, the use of other substances such as cocaine, amphetamines, alcohol and cannabis exerts a negative influence.

The surveyed therapists also believe that personality type has a role to play. Patients with avoidant, dependent or compulsive personality types are particularly well suited to psychedelic-assisted therapy. Caution should be taken with patients who have paranoid, schizoid and schizotypal personal types. Narcissistic and antisocial personality types and emotionally unstable borderline personalities proved more difficult to categorize. “The knowledge of which patient profiles are fundamentally suited to this form of therapy, and the profiles that can be harmed, will enable us to better control who receives such therapy. It represents a further step toward precision psychiatry in a highly dynamic field,” underscores Betzler.

The right setting

The study emphasized another point: psychedelic-assisted therapy is far from an easy “miracle cure”. Instead, treatment success depends to a significant extent on careful preparation, professional guidance during the session, and diligent follow-up care to process the experience. Prior to the therapy, patients should have the opportunity to build trust with their therapist, formulate clear objectives and state their fears. It is also advisable to undergo therapy exclusively at specialized centers and within the context of clinical studies. This is the only way to ensure that therapists operate on a scientific basis and take decisions accordingly.

Therapists who offer psychedelic substances in other settings not subject to clinical controls or regulation view the prospects of success more optimistically across the board. “Analysis of data for this sub-group showed that, whether among older people, those with severe illnesses or those with limited social support – and even putting aside previous negative experiences – reservations about using substances in underground settings were significantly lower than in legal settings,” says Betzler. “In an ideal scenario, the parameters we have identified as being decisive will be used in patient selection in the future.” Support could also come in the form of a digital tool, which the study team hopes to develop with the data collected to help forecast the probability of success of psychedelic-assisted therapy.

*Viljoen G et al. Therapist-rated predictors of response to psychedelic-assisted therapy. Nat. Mental Health 2026 Apr 29. doi: 10.1038/s44220-026-00642-4

Links:
Original publication
Department of Psychiatry and Neurosciences, CCM
PREPARE (Predictors of Psychedelic Assisted Therapy Response)
EPIsoDE study on the effects of psilocybin in people with depression

Journal

Nature Mental Health

DOI

10.1038/s44220-026-00642-4

Method of Research

Survey

Subject of Research

People

Article Title

Therapist-rated predictors of response to psychedelic-assisted therapy.

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Huxley, Aldous The Doors of Perception

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Key magic mushroom ingredient makes fish less aggressive and lazier

Chemical compound in magic mushrooms may reduce energetically costly social behaviors like aggressive swimming bursts, shows study demonstrating first evidence of calming effect in fish

Frontiers

More than 200 mushrooms – primarily those belonging to a genus of gilled mushrooms called Psilocybe – contain the psychoactive compound psilocybin. In the brain of mammals, this chemical can bind to serotonin receptors and influence behavior and emotions, including aggression, appetite, and mood. Its effects on the social behavior of animals, however, remain largely undescribed.

In a new Frontiers in Behavioral Neuroscience study, researchers in Canada have tested whether the effects of psilocybin extend to the social behavior of the amphibious mangrove rivulus fish (Kryptolebias marmoratus).

“We show that an acute, low dose of psilocybin significantly reduces activity and aggressive attack behavior during social interactions in adult mangrove rivulus fish, a species that is naturally highly aggressive,” said first author Dayna Forsyth, a research associate and former MSc student at Acadia University in Nova Scotia.

“These findings provide the first evidence that psilocybin can selectively reduce escalated aggression in a vertebrate model without suppressing social interaction,” added senior author Dr Suzie Currie, a biologist at The University of British Columbia.

Calm waters

Mangrove rivulus fish are innately aggressive, especially when paired with another individual. Their aggressive behaviors are straightforward and subtle changes can easily be detected. These fish are also self-fertilizing and produce embryos that are genetically identical. Therefore, this model ensures all observed effects are caused by psilocybin treatment rather than genetic differences between fish.

The team used three genetically distinct, laboratory-bred lines. Fish from one line were exposed to psilocybin, fish from a second served as stimulus fish. A third line was used to quantify whole-body concentrations and absorption of psilocybin.

For the first phase of the experiment, the focal fish was added into a tank containing a stimulus fish to measure baseline behavior. The fish were separated by an opaque cover placed over a fiberglass mesh barrier through which the fish could see and smell, but not reach, each other. After a five-minute adjustment period to the shared tank, the opaque barrier was removed and interaction monitored.

24 hours later, the same focal fish was put in a water tank in which psilocybin was dissolved. After exposure to the substance for 20 minutes, the fish was added into the tank occupied by the same stimulus fish of the day before. After removal of the opaque barrier, interaction was observed again.

Magic mushroom, mellow fish

Observation of behaviors to measure activity (time spent moving) and aggression levels (including swimming bursts) revealed that fish dosed with psilocybin showed decreased levels of activity and performed fewer swimming bursts compared to specimen that hadn’t received psilocybin treatment.

“Swimming bursts are high‑energy attack behaviors that represent an escalation of aggression towards the stimulus fish without making physical contact,” explained Currie. “Other types of aggressive behaviors, like head‑on displays, are more about communication and social assessment and require very little energy.”

“Psilocybin’s calming effect appears to selectively reduce energetically costly, escalated behaviors while lower‑energy social display behaviors remained largely unchanged,” said Forsyth. “This suggests that this compound can selectively dampen escalated social conflict rather than shutting down behavior altogether.”

Psilocybin also influenced activity levels, with dosed fish spending less time moving than control fish when paired with a conspecific.

Diving deeper

In the long run, non-human models in drug-screening experiments like this can provide robust results that can later be translated to humans. In the future, findings like those made here could help inform therapeutic research by clarifying which aspects of social behavior are most sensitive to psilocybin. The team cautioned, however, that the current study did not test clinical treatments and results from fish cannot be directly extrapolated to humans.

The study also focused on single doses and short periods of exposure, and didn’t examine long-term effects, repeated dosing, or adaptation over time. Future studies are needed to confirm whether the lower level of aggression observed here can be sustained.

“Future studies can build on this work to explore how psilocybin alters neural signaling, which serotonin pathways are involved, and why some aspects of social behavior are affected while others are not,” concluded Currie. “These are questions that are difficult or impossible to answer directly in humans.”

Journal

Frontiers in Behavioral Neuroscience

DOI

10.3389/fnbeh.2026.1767175

Method of Research

Experimental study

Subject of Research

Animals

Article Title

The magic of mushrooms: Psilocybin influences behaviour in the mangrove rivulus fish, Kryptolebias marmoratus

Article Publication Date

7-May-2026

Drug contamination traces may linger in cars, even after ventilation

Testing on methamphetamine smoke taint under controlled conditions

Flinders University

Meth manufacturing — image:
Methamphetamine can be manufactured in vehicles in transportable and generally small-scale clandestine laboratories. Additionally, private and commercial vehicles can be used for transportation or smoking of the drug.
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Credit: Flinders University

Environmental health experts at Flinders University have found open windows and ventilation can reduce but not completely remove methamphetamine contamination on most hard surfaces of a car after an extended period.

In a new study, researchers tested various parts of a car’s interior to show concentrations in the air and surfaces exposed to controlled release of methamphetamine smoke. While levels generally dropped over time, the experts warn indirect exposure could still occur, in particular in textile or soft surfaces.

The latest results, published in the journal Forensic Chemistry, highlight the complexity of managing meth contamination in contained spaces where various fabric types showed differing levels of meth smoke taint – even after eight weeks of ventilation.

“Redistribution of methamphetamine can occur, and remediation attempts may be hampered by methamphetamine ‘stored’ in non-surface material including the air-conditioning unit, upholstery, and underlying foam,” says lead author Gemma Kerry, from Flinders University’s College of Science and Engineering.

“And some fabric concentrations appeared to slightly increase after venting for a total of eight weeks. This may have occurred because of relatively high temperatures reported inside the car during the venting period, volatilising the drug and resulting in transfer.”

Lead author, PhD in Forensic Chemistry and Environmental Health Gemma Kerry, is investigating levels and subsequent risk to other people’s health of meth contamination left on household upholstery, underlying foam and even air-conditioning units.

Senior researcher Professor Kirstin Ross adds: “Testing and remediation for methamphetamine in contaminated vehicles, residences and elsewhere is important to protect public health.

“This latest data on methamphetamine distribution from smoking and ventilation could aid in further investigation of contamination and remediation in cars.

“Individuals exposed to indirect contamination may have adverse health symptoms including respiratory problems, headaches and behavioural and cognitive issues.”

This makes it important to determine the overall methamphetamine contamination extent of cars to provide the public with safeguards when buying or using vehicles, the Flinders University experts conclude.

Under a special licence, the Flinders University team used controlled emissions of methamphetamine smoke in a car with no known prior contamination.

After three smoking events, there was a general concentration increase on the car surfaces, on four fabric types placed on the car seat and seat backrests, and in the sampled air.

The highest surface concentrations were reported from the driver’s overhead – likely due to rising smoke.

The highest methamphetamine concentrations were observed from cotton and faux leather, with the lowest concentrations from polyester and neoprene fabrics. For cotton, faux leather, and neoprene fabrics generally lower concentrations were reported from the seat back when compared to the seat.

Air concentrations ranged from 0.19 to 0.96 micrograms per cubic metre (μg/m3) in the driver area and the rear storage area after three controlled smokes.

Air testing detected small amounts of methamphetamine in the air. By comparison, tobacco smoke could contain hundreds of thousands of micrograms per cubic metre of airborne particles in indoor environments.

After the contaminated car’s windows were opened for decontamination purposes, the concentrations in the air and on the surfaces generally decreased after venting for a total of eight weeks after the last smoking event.

The Flinders University research will help law enforcement agencies, vehicle dealerships, vehicle lenders and owners faced with testing and cleaning contaminated vehicles, in particular stolen or second-hand cars.

The new article, ‘Controlled smoking of methamphetamine in a car and initial remediation by ventilation: Analysing air, surfaces and fabrics’ (2026) by Gemma L Kerry, Kirstin E Ross, Jackie Wright and G Stewart Walker was published Forensic Chemistry DOI: 10.1016/j.forc.2025.100723.

All testing activities were done with Flinders University Risk Assessment and Safe Work Procedure and under Government of South Australia Research, Instruction, Training or Analysis Permit (Controlled Substances Act, 1984 Permit Number: 2024-83442).

Journal

Forensic Chemistry

DOI

10.1016/j.forc.2025.100723

Method of Research

Observational study

Subject of Research

Not applicable

Article Title

Controlled smoking of methamphetamine in a car and initial remediation by ventilation: Analysing air, surfaces and fabrics’