Cannabis use has increased significantly around the world.
st research shows that regular cannabis use can increase a person’s risk for several health concerns, including risk factors for dementia.
Scientists from the University of Colorado Anschutz Medical Campus have found that heavy cannabis use may negatively impact a person’s working memory.
Recent research shows the use of cannabis has grown significantly around the world, from about 180.6 million people in 2011 to 219 million in 2021.
Much of this growth has been spurred on by recent moves to legalize the use of cannabis in many countries, including the United States, Canada, Thailand, Spain, South Africa, the Netherlands, and Uruguay.
Past studies show that regular cannabis use can increase a person’s risk for certain health issues such as lung damage, mental health issuesTrusted Source, strokeTrusted Source, and heart attackTrusted Source.
Additionally, previous research shows a potential link between cannabis use and known risk factors for dementia.
Now researchers from the University of Colorado Anschutz Medical Campus report that heavy cannabis use may negatively impact a person’s working memoryTrusted Source, which helps in completing cognitive tasks such as learning and understanding language.
For this study, researchers analyzed data from more than 1,000 young adults aged 22 to 36 who were categorized as one of the following:
heavy cannabis users — used more than 1,000 times over their lifetime
moderate users 10 to 999 times used during their life
nonusers who used cannabis less than 10 times.
Scientists analyzed the neural responses in the brains of participants captured through magnetic resonance imaging (MRI) as they completed seven different cognitive tasks, including tasks testing motor skills, emotion, reward, and working memory.
“I have had an interest in learning how substances such as cannabis affect brain function since I was a teenager,” Joshua L. Gowin, PhD, assistant professor in the Department of Radiology at the University of Colorado Anschutz Medical Campus and first author of this study, told Medical News Today.
“I was fortunate to have an opportunity to do some of that work with this study. I was not only interested in working memory, but I wanted to see how cannabis affected a range of different brain functions, so we looked at seven tasks,” he added.
Of the seven cognitive tasks, Gowin said working memory was the only one that showed an effect of cannabis.
Researchers found that 63% of lifetime heavy cannabis-using participants and 68% of recent cannabis users showed reduced brain activity during their working memory task.
“We found that brain function related to working memory showed effects of cannabis, where heavy cannabis users had lower brain activation,” Gowin explained.
While the adjustment for potential confounding factors indicated that the link between cannabis use and memory problems was not a strong one, the researchers maintain that the potential connection remains a significant one to take into account.
“The effects were small but reliable, so it won’t turn Einstein into Fred Flintstone, but it could add a few clouds into an otherwise clear sky,” said Gowin.
Additionally, scientists discovered that participants who were heavy cannabis users also had reduced brain activity in certain areas of the brain, including the dorsolateral prefrontal cortex, dorsomedial prefrontal cortex, and anterior insulaTrusted Source, which are not only important for memory, but also other processes such as attention and decision-making.
“The cannabinoid system is widespread in the brain, so modulating cannabinoid function with products like THC could have a wide range of possible effects. We wanted to better understand which brain functions show the biggest effects. But the other effects could all be important in their own way. I hope that these results will add to our understanding of possible effects of cannabis and help people make informed choices for their own health.”
– Joshua L. Gowin, PhD
“We are currently exploring whether controlled administration of THC reduces brain activation relative to a placebo, since the current study did not control for when the participants used cannabis,” Gowin added.
MNT spoke with Clifford Segil, DO, neurologist at Providence Saint John’s Health Center in Santa Monica, CA, about this study.
“This study in young adults shows what we see in clinical practice that people that choose to use CBD or THC as either edible or smokeable products have proven memory issues,” Segil, who was not involved in the study, commented.
“This shows that people that were young adults, that had heavy use and recent use, had memory problems. So the expectation is choosing to use cannabis products is going to cause you to have memory loss in the long term and the short term,” he explained.
“There’s two things I’d like to see (as next steps for this research,” Segil continued. “I’d like to see, one, if they could reproduce this with driving tasks, to see if both recent and chronic use decreases people’s ability to drive.“
“And two, I would like to see them do this with a subset of patients that are using medical marijuana, to see if that group of patients that are getting medical marijuana have the same kind of memory cognitive issues. So you can do a risk-benefit ratio for people choosing to use cannabis for medical uses,” he added.
MNT also spoke with Jasdeep S. Hundal, PsyD, ABPP-CN, a board-certified clinical neuropsychologist and director of The Center for Memory & Healthy Aging Hackensack Meridian Jersey Shore University Medical Center in New Jersey, about this study.
“As a neuropsychologist who works with patients at risk for cognitive decline, my first reaction to this study was concern, but not surprise,” Hundal, who was also not involved in the study, said.
“We have long suspected that regular, heavy cannabis use may have consequences for brain function, particularly in areas related to working memory and executive functioning. The findings align with what we often observe clinically that some patients who use cannabis regularly report subjective memory difficulties, slower processing speed, and reduced cognitive flexibility, even if they do not have a diagnosed neurodegenerative condition.”
– Jasdeep S. Hundal, PsyD, ABPP-CN
“Findings like these should prompt more cautious and informed discussions between doctors and patients, especially those at high risk for Alzheimer’s disease or other memory-related conditions,” he continued. “While cannabis is often perceived as harmless or even beneficial for certain medical conditions, this study underscores potential negative cognitive effects, particularly on working memory and executive function, both of which are crucial for maintaining independence and quality of life.”
Taking care of oneself requires a multi-faceted approach: brain, heart, and metabolic health. What research in 2024 has shown us is that improving our health in these areas comes down to three main factors: sleep, diet, and exercise. But how does one start taking action with this intention? And how can we break down such lifestyle changes into manageable steps? In this podcast episode, Medical News Today shares three actionable resolutions that can help improve your health in the new year.
As humans, we are all capable of growth and change. And perhaps, one of the most influential times of the year for transformation and setting the stage for change is New Year’s.
When it comes to making resolutions for health or any other area of life, we may set unrealistic or very large goals that set us up for failure from the start. The key, according to experts, is to start small and be as specific as possible—whether that be via setting a time frame or measurable results.
In our August 2023 podcast episode, we had touched on how human behavior inherently resists change unless the optimal conditions are present. One such factor was whether it would be beneficial.
As many as 70 million people have consistent sleeping issues.
Not getting enough sleep each night can raise a person’s risk for several health concerns, including cognitive decline and dementia.
For the first time a new study describes the synchronized oscillations during sleep that power the brain’s glymphatic system to help remove ‘waste’ associated with neurodegenerative diseases, via a mouse model.
Researchers also found that a commonly prescribed sleep aid might suppress those oscillations, disrupting the brain’s waste removal during sleep.
Looking at all the possible factors that might contribute to potential cognitive decline risk is important, particularly as new research estimates that dementia risk the risk after the age of 55 among Americans has now more than doubled.
Although doctors recommend that adults over the age of 18 get at least 7 hoursTrusted Source of quality sleep each night, the most recent data suggest that many may face consistent sleep issues, such as insomnia and sleep apnea.
Data from 2022 suggest that, in the United States alone, 39% of adultsTrusted Source over the age of 45 were not getting sufficient sleep.
Past studies report that not getting enough sleep each night can increase a person’s risk for several health concerns, including brain-related conditions, such as cognitive declineTrusted Source and dementia.
“Sleep allows the brain to go offline, shut down processing of the external world and focus on maintenance tasks, such as immune surveillance and removal of waste,” Natalie Hauglund, PhD, a postdoctoral fellow at the Universities of Copenhagen in Denmark, and Oxford in the United Kingdom, explained to Medical News Today. “The lack of sleep is associated with cognitive impairment and disease development.”
But could some sleep aids also contribute to poorer brain health as we age? It is now more important than ever to study all the possible factors that might contribute to cognitive decline, particularly seeing that a new study published in Nature MedicineTrusted Source estimates that dementia risk after the age of 55 among Americans has more than doubled, compared to past figures.
Hauglund is the first author of another study, which appears in the journal CellTrusted Source, and that, for the first time, describes the synchronized oscillations during sleep that power the brain’s glymphatic system to help remove “waste” associated with neurodegenerative diseases, via a mouse model.
The study also reports that the commonly prescribed sleep aid zolpidemTrusted Source — marketed under the name Ambien — may suppress those oscillations, disrupting the brain’s waste removal during sleep.
For this study, researchers used various technologies to record brain activity while mice were both awake and asleep.
Scientists observed that slow synchronized oscillations of the neurotransmitter norepinephrine, along with cerebral blood and cerebrospinal fluid (CSF)Trusted Source, combine during non-rapid eye movement (non-REM) sleep, essentially power the brain’s waste-removing glymphatic system.
“Our brain is unique in that it does not have lymphatic vessels, which removes waste products such as dead cells and bacteria from the rest of our body,” Maiken Nedergaard, MD, PhD, professor at the Universities of Rochester and Copenhagen and lead author of this study told MNT.
“Instead, the brain uses cerebrospinal fluid, a brain fluid that is produced inside the brain, to flush the brain tissue and wash away unwanted molecules,” she explained.
“The cleaning system of the brain is called the glymphatic system. Importantly, the glymphatic system is only on during the deep part of sleep called non-REM sleep. This is because of a neuromodulator called norepinephrine, which during non-REM sleep is released in slow cycles roughly every 50 seconds.”
– Maiken Nedergaard, MD, PhD
“Norepinephrine binds to the muscle cells of the arteries, which makes them constrict,” Nedergaard told us. “Therefore, the slow oscillation in norepinephrine concentration drives a slow fluctuation in the diameter of the arteries and in the blood volume in the brain.”
”This dynamic change in blood volume works like a pump to transport cerebrospinal fluid along the arteries towards the brain and through the brain tissue. Thus, norepinephrine coordinates the synchronized constriction and dilation of the blood vessels which drives the glymphatic system,” she detailed.
Researchers also examined if sleep aids might replicate the natural oscillations needed for glymphatic function. They focused their research on the sedative zolpidem.
They discovered that zolpidem appeared to halt norepinephrine oscillations, interrupting the glymphatic system’s waste removal in the brain during sleep.
“Sleep aids may provide a short-cut to sleep, but our study shows that the sleep you get with sleep medication may lack the beneficial effects of natural, restorative sleep,” Hauglund said. “Our findings underscore that sleep aids should only be used for short periods of time and as a last resort.”
Nedergaard explained that:
“Sleep is crucial as it gives the brain time to perform homeostatic housekeeping tasks such as waste removal. On the contrary, sleep aids block the neuromodulators that drive the waste removal system and prevent the brain [from] properly preparing for a new day.”
MNT also spoke with Clifford Segil, DO, a neurologist at Providence Saint John’s Health Center in Santa Monica, CA, about this study.
According to Segil, who was not involved in the recent research, “it is extremely unlikely the benefits of increased sleep which occurs when patients use a sleep aid like zolpidem are outweighed by any claimed potential adverse effect of this medication decreasing REM sleep, which then in turn decreases brain neurotransmitter levels, [which] then in turn decreases brain protein levels,”
“There are too many ‘in turn’ claims to cause me any concern [that] there is any clinical significance to the research,“ he told us. “Clinical neurologists like me are not concerned [that] using zolpidem appropriately in elderly patients who can’t sleep will cause dementia.”
Furthermore, he pointed out: “In the year 2025, there remains no accepted response on why we sleep. Different researchers make different claims and sometimes these are the same and sometimes they are different. We know healthy sleep makes us healthy and poor sleep makes us unhealthy.”
“For clinical neurologists like me, it is challenging to agree that a sleeping medication will cause dementia, and I would reassure my patients the benefits or a good night sleep outweigh any claimed potential risk these can cause memory loss as you age or dementia,” Segil added.
Finally, MNT spoke with Peter G. Polos, MD, PhD, FCCP, FAASM, an assistant professor of sleep medicine at the Hackensack Meridian Neuroscience Institute at JFK University Medical Center in New Jersey, about this research.
Polos, who was not involved in the study, commented that he found the results intriguing.
“There is no doubt that the interaction between the glymphatic system and various transmitters and waste products in the brain can work in synchrony,” he said.
“This study suggests that alterations in this tight balance have potential cellular and perhaps clinical consequences. While fascinating, we must remind ourselves that this is an animal study and, as is often the case, extrapolation of animal data to humans must be done cautiously. Nonetheless, it does give clinicians a phenomenon that is deserving of some discussion.”
– Peter G. Polos, MD, PhD, FCCP, FAASM
“If more work were to be done in this area, we certainly would like to see if studies could assess the impact of sleep aids on human glymphatic flow,” Polos continued. “This of course would require noninvasive techniques and perhaps some advanced imaging. Such information, even if in small numbers, would be of benefit.”
“The interaction between the brain, quality sleep, and overall health cannot be understated,” he added. “The rhythmic nature of sleep and the regular cycling of sleep stages have been well studied, We have learned much about the effects of alterations in the brain and their impact on sleep, We do have much more to learn and so we, as sleep physicians, fully support continued research in the relationship between the brain, sleep, and overall health.”
Fetuses of pregnant people who gained excess weight in the first trimester of pregnancy show signs of excess fat distribution in the upper arm and in the abdomen, according to a study by researchers at the National Institutes of Health. These findings may inform efforts to prevent excessive weight gain early in life, a risk factor for adult obesity and related conditions, such as heart disease, high blood pressure and diabetes. The study, conducted by researchers at NIH'sEunice Kennedy ShriverNational Institute of Child Health and Human Development and other institutions, appears in theAmerican Journal of Clinical Nutrition.
The authors analyzed data from an earlier study of more than 2,600 singleton pregnancies, which included information on maternal weight before and during pregnancy and three-dimensional (3D) ultrasound scans (up to five) throughout pregnancy.The authors found that pregnant people with excessive weight gain -- defined as more than 2 kilograms (about 4.4 pounds) in the first trimester -- had fetuses with larger abdominal circumference and abdominal area and larger fetal arm fat thickness, when compared to pregnant people with adequate weight gain.
Fetuses from the excessive weight gain group continued to have greater arm thickness and abdominal measurements through the end of pregnancy, even when weight gain was not considered excessive during the second and third trimesters.
In contrast, most previous studies have not examined fetal 3D measures during pregnancy and have only linked total weight gain across pregnancy, not just in the first trimester, with birthweight.
The authors wrote that their findings suggest that the timing of weight gain, instead of total weight gain, could be important for developing efforts to prevent excess fetal size and reduce the risk of heart disease and other conditions later in life.
