A new study published in Psychopharmacology investigates the biological phenomenon known as reintoxication in cannabis users. The findings indicate that acute physical stress caused by cold water immersion does not release stored THC back into the bloodstream. This research suggests that moderate physical stressors encountered in daily life are unlikely to cause a person to test positive for cannabis or experience impairment long after their last use.

The primary psychoactive compound in cannabis is delta-9-tetrahydrocannabinol, commonly known as THC. This chemical is highly lipophilic, meaning it dissolves readily in fats rather than water.

When a person consumes cannabis, the body metabolizes much of the THC, but a significant portion is absorbed and stored in fat tissue throughout the body. These fat deposits can act as a long-term storage depot for the drug. Traces of THC have been detected in human fat biopsies weeks after consumption has stopped.

This biological storage mechanism has led scientists to propose the reintoxication hypothesis. The body naturally breaks down fat deposits for energy when it faces a deficit, such as during periods of starvation or intense physical stress. This process is called lipolysis. The hypothesis suggests that when the body breaks down fat cells during stress, the stored THC could be released back into the bloodstream along with the stored energy.

“It has been suggested that THC stored in body fat could be released back into circulation during periods of acute stress, potentially increasing blood THC concentrations,” said study author Danielle McCartney, an associate lecturer in pharmacology at the University of Sydney.

“This idea has been discussed in scientific and legal contexts, but there is very little direct human evidence to support it. We wanted to test this under controlled conditions to see whether acute stress actually increases blood THC concentrations in regular cannabis users.”

Previous research on animals has provided some evidence for this phenomenon. Studies involving rats showed that stress hormones and food deprivation could increase blood THC concentrations in animals that had been pre-treated with the drug.

Human studies, however, have been less conclusive. One study found that intense exercise significantly raised plasma THC levels in regular users. Another study involving food deprivation and running produced mixed results. The authors of the current study aimed to clarify these findings by using a different form of stress.

The researchers recruited fifteen volunteers for the experiment. The sample included nine females and six males. All participants were regular cannabis users who reported consuming the drug at least three days per week. On average, the group used cannabis five days a week. To ensure that any THC detected was not from immediate use, participants were required to abstain from cannabis for at least twelve hours before the test. They also fasted for more than eight hours to ensure their bodies were ready to metabolize fat.

The chosen stressor for this experiment was cold water immersion. This method is known to trigger a robust “fight or flight” response and stimulate the breakdown of fats. Participants sat in a bath filled with water cooled to approximately 10 degrees Celsius, or 50 degrees Fahrenheit. They remained submerged up to their clavicles for ten minutes. This duration and temperature were selected to induce significant physiological stress without posing a danger to the volunteers.

The research team collected detailed measurements at three specific time points. They took baseline measurements immediately before the cold water immersion. They collected a second set of data five minutes after the participants exited the bath. A final set of data was collected two hours after the intervention. At each point, the team drew blood samples and administered cognitive tests.

The blood samples were analyzed for several chemical markers. The researchers looked for plasma THC and its metabolites to see if concentrations rose after the stress. They also measured levels of glycerol and free fatty acids. These compounds are byproducts of fat breakdown. An increase in glycerol and free fatty acids serves as biological proof that lipolysis is occurring. Additionally, the team monitored heart rate, blood pressure, and body temperature to quantify the physiological stress response.

Subjective and cognitive effects were also assessed. Participants completed computerized tasks designed to measure attention, processing speed, and psychomotor function. Specifically, they performed the Digit Symbol Substitution Task, the Divided Attention Task, and the Paced Serial Addition Task. Participants also used visual scales to rate how “stoned” or “euphoric” they felt, as well as their levels of calmness and nervousness.

The results demonstrated that the cold water immersion successfully induced a stress response. Participants exhibited elevated heart rates and higher systolic blood pressure following the bath. Their body temperature dropped as expected. Subjective ratings confirmed that the participants felt less calm and more nervous after the exposure.

The blood analysis confirmed that the intervention triggered the breakdown of fat. Concentrations of glycerol and free fatty acids increased significantly from the baseline to the post-intervention measurements.

Despite the successful induction of stress and fat breakdown, the researchers found no corresponding increase in blood THC levels. The concentrations of THC remained stable across all three time points. The levels of 11-COOH-THC, a primary metabolite of the drug, also did not rise following the cold water stress. In fact, the concentration of this metabolite tended to decrease slightly over the two-hour monitoring period, likely due to natural clearance from the body.

Cognitive performance remained unaffected by the stressor. The participants showed no signs of impairment on any of the computerized tasks. Their reaction times and accuracy scores did not change significantly after the cold water immersion. This aligns with the lack of change in blood THC concentrations. Without a spike in the drug’s presence in the bloodstream, functional impairment would not be expected.

There was a minor change in subjective sensations. Participants reported a slight increase in feeling “stoned” immediately after the cold bath. However, the researchers note that this effect was negligible. The average rating on a 100-point scale increased by fewer than three points. The authors suggest this was likely a result of the general physiological shock of the cold water or a placebo effect, rather than true intoxication.

The researchers also examined oral fluid, which is commonly tested in roadside drug screenings. The researchers found that the cold water stress did not lead to a surge in positive results for oral fluid tests. This provides evidence that stress-induced fat breakdown is unlikely to cause a false positive on saliva-based drug tests used by law enforcement.

“We found that brief physical stress, like cold water immersion, does not increase blood THC concentrations or cause intoxication in regular cannabis users,” McCartney told PsyPost. “This suggests that everyday stressors are unlikely to meaningfully impact blood THC concentrations. That said, our participants were moderate regular users rather than very heavy or dependent users, so the findings should be interpreted in that context.”

The researchers offered several explanations for why their results differed from the previous study that found exercise increased THC levels. The primary factor appears to be the intensity of the stress. The exercise study involved thirty-five minutes of cycling, which raised heart rates to roughly 130 beats per minute. The cold water immersion in this study only raised heart rates to about 80 beats per minute.

Consequently, the exercise study induced a much stronger metabolic response. The increase in free fatty acids observed in the exercise study was nearly six times greater than the increase observed in the cold water study.

It appears that while cold water causes some fat breakdown, it may not be intense enough to liberate a detectable amount of stored THC. The stressor in the real world would likely need to be severe and prolonged to mimic the effects seen in the exercise study.

Another factor could be the usage habits of the participants. The volunteers in this study were moderate regular users. Individuals with heavier consumption habits might store larger quantities of THC in their fat tissue. It is possible that a similar stressor could trigger a release in very heavy users or those with a higher body mass index.

Studies involving heavier cannabis users or different types of psychological and physical stress would provide a more complete picture. For now, the evidence indicates that brief, moderate physical stress is not a risk factor for sudden cannabis intoxication.

The study, “Does acute stress induced via cold water immersion increase blood THC concentrations in regular cannabis users,” was authored by Danielle McCartney, Jordan Levoux, Rebecca Gordon, Laura Sharman, Katie Walker, Jonathon C. Arnold, and Iain S. McGregor.

A compound found in cannabis may help protect the brain from early memory and social problems linked to Alzheimer’s disease. A new animal study published in Neuropsychopharmacology found that cannabidiol prevented cognitive decline in rats by reducing brain inflammation and activating key brain receptors.

Alzheimer’s disease is a progressive brain disorder best known for causing memory loss, but it also affects thinking, decision-making, and social engagement. Scientists increasingly recognize that inflammation in the brain plays a major role in driving these symptoms, especially in the early stages of the disease.

Cannabidiol is a chemical compound extracted from the cannabis plant that does not cause a “high.” In recent years, it has gained attention for its potential anti-inflammatory and neuroprotective properties. While cannabidiol is already used in some medical treatments, its possible role in preventing or slowing Alzheimer’s disease remains under investigation.

Roni Shira Toledano and Irit Akirav from the University of Haifa, Israel, wanted to explore whether cannabidiol could stop Alzheimer-like symptoms from developing in the first place, rather than trying to reverse damage after it occurs. They were particularly interested in the role of type 1 cannabinoid receptors, which are found throughout the brain and are involved in memory, learning, and inflammation control.

To test this, the scientists conducted experiments using male rats. The rats were injected with a substance known as streptozotocin, which triggers brain changes similar to those seen in Alzheimer’s disease, including amyloid β-protein accumulation and tau phosphorylation. Some of the rats then received regular doses of cannabidiol, while others did not.

The researchers monitored the animals’ behavior using standard tests of memory, learning, and social interaction. They also examined brain tissue to measure levels of inflammation and to determine whether type 1 cannabinoid receptors were involved in cannabidiol’s effects.

The results revealed that the rats that did not receive cannabidiol showed clear memory problems and reduced interest in social interaction—behaviors commonly seen in Alzheimer’s disease. In contrast, rats treated with cannabidiol performed normally on memory tasks and continued to interact socially with other rats.

Brain analysis revealed that cannabidiol-treated rats had lower levels of inflammation compared to untreated rats. When researchers blocked type 1 cannabinoid receptors using a different substance, many of cannabidiol’s protective effects disappeared, suggesting that these receptors play an important role in how cannabidiol protects the brain.

The findings suggest that cannabidiol may help prevent cognitive and social decline by calming inflammation in the brain and supporting normal brain signaling. The researchers emphasize that cannabidiol did not simply mask symptoms, but appeared to prevent damage from developing in the first place.

“As current Alzheimer’s disease treatments are limited, our study highlights cannabidiol as a promising candidate, demonstrating for the first time that a low dose can prevent behavioral and molecular deficits in a rodent model of [the disease],” the authors concluded.

However, the study has important limitations. It was conducted only in male rats, and animal models do not perfectly replicate human Alzheimer’s disease. Additionally, the study focused on early-stage changes rather than long-term disease progression.

The study, “Cannabidiol prevents cognitive and social deficits in a male rat model of Alzheimer’s disease through CB1 activation and inflammation modulation,” was authored by Roni Shira Toledano and Irit Akirav.

Recent survey data suggests that cannabis-infused beverages may serve as an effective tool for individuals looking to curb their alcohol consumption. People who incorporated these drinks into their routines reported reducing their weekly alcohol intake and engaging in fewer episodes of binge drinking. The findings were published in the Journal of Psychoactive Drugs.

Alcohol consumption is a well-documented public health concern. It is linked to nearly 200 different health conditions. These include liver disease, cardiovascular issues, and various forms of cancer.

While total abstinence is the most effective way to eliminate these risks, many adults choose not to stop drinking entirely. This reality has led public health experts to explore harm reduction strategies. The goal of harm reduction is to minimize the negative consequences of substance use without necessarily demanding complete sobriety.

Cannabis is increasingly viewed through this harm reduction lens. It generally presents fewer physiological risks to the user compared to alcohol. The legalization of cannabis in many U.S. states has diversified the market beyond traditional smokable products. Consumers can now purchase cannabis-infused seltzers, sodas, and tonics. These products are often packaged in cans that resemble beer or hard seltzer containers.

This similarity in packaging and consumption method is notable. It allows users to participate in the social ritual of holding and sipping a drink without consuming ethanol. Jessica S. Kruger, a clinical associate professor of community health and health behavior at the University at Buffalo, led an investigation into this phenomenon. She collaborated with researchers Nicholas Felicione and Daniel J. Kruger. The team sought to understand if these new products are merely a novelty or if they serve a functional role in alcohol substitution.

The researchers designed a study to capture the behaviors of current cannabis users. They distributed an anonymous survey between August and December of 2022. Recruitment took place through various channels to reach a broad audience.

The team placed recruitment cards with QR codes in licensed dispensaries. They also utilized email lists from these businesses. Additionally, they posted links to the survey on nearly 40 cannabis-related communities on the social media platform Reddit.

The final analytic sample consisted of 438 adults. All participants had used cannabis within the past year. The survey incorporated questions from the Behavioral Risk Factor Surveillance System. This is a standard tool used by the Centers for Disease Control and Prevention to track health-related behaviors. The researchers used these questions to assess alcohol consumption frequency and intensity.

The study aimed to compare the behaviors of those who drank cannabis beverages against those who used other forms of cannabis. It also sought to compare alcohol habits before and after individuals began consuming cannabis drinks. Roughly one-third of the respondents reported using cannabis beverages. These users typically consumed one infused drink per session.

The researchers found differences in substitution behaviors between groups. Participants who consumed cannabis beverages were more likely to report substituting cannabis for alcohol than those who did not drink them. The data showed that 58.6 percent of beverage users reported this substitution. In contrast, 47.2 percent of non-beverage users reported doing so.

The study provided specific data regarding changes in alcohol intake levels. The researchers asked beverage users to recall their alcohol consumption habits prior to adopting cannabis drinks. Before trying these products, the group reported consuming an average of roughly seven alcoholic drinks per week. After they started using cannabis beverages, that average dropped to approximately 3.35 drinks per week.

Binge drinking rates also saw a decline. The researchers defined a binge drinking episode based on standard gender-specific thresholds. Before initiating cannabis beverage use, about 47 percent of the group reported binge drinking less than once a month or never. After incorporating cannabis drinks, the proportion of people reporting this low frequency of binge drinking rose to nearly 81 percent.

Most participants did not replace alcohol entirely. The survey results indicated that 61.5 percent of beverage users reduced their alcohol intake. Only about 1 percent reported stopping alcohol consumption completely.

A small minority, roughly 3 percent, reported increasing their alcohol use. This suggests that for most users, cannabis beverages act as a moderator for alcohol rather than a complete replacement.

The study also examined the potency of the beverages being consumed. Most respondents chose products with lower doses of Tetrahydrocannabinol (THC). Two-thirds of the users drank beverages containing 10 milligrams of THC or less. This dosage allows for a milder experience compared to high-potency edibles. It may facilitate a more controlled social experience similar to drinking a glass of wine or a beer.

Daniel J. Kruger, a co-author of the study, noted the potential reasons for these findings. He suggests that the similarity in the method of administration plays a role. People at parties or bars are accustomed to having a drink in their hand. A cannabis beverage allows them to maintain that behavior. It fits into the social context more seamlessly than smoking a joint or taking a gummy.

There are limitations to this research that require consideration. The study relied on retrospective self-reports. Participants had to recall their past alcohol consumption. This relies on memory and can be subject to bias. The sample was also a convenience sample rather than a nationally representative one. Many respondents were recruited from New York State dispensaries or specific online communities.

The researchers also point out potential risks associated with these products. Cannabis beverages and edibles have a slower onset of effects compared to inhalation. It takes time for the digestive system to process the cannabinoids. This delay can lead inexperienced users to consume more than intended. Accidental overconsumption can result in negative physical and mental health outcomes.

Furthermore, there is the issue of dual use. Most participants continued to drink alcohol, albeit in smaller quantities. Combining alcohol and cannabis can intensify impairment. The authors note that this interaction needs further study to ensure public safety.

Future research is necessary to validate these preliminary findings. The authors suggest that longitudinal studies would be beneficial. Such studies would track individuals over time rather than relying on past recall. This would provide a clearer picture of whether the reduction in alcohol use is sustained in the long term.

Public education will be key as this market expands. Consumers need to understand the differences between alcohol and cannabis impairment. They also need accurate information regarding dosing and onset times. Policies that ensure clear labeling and child-proof packaging remain essential for harm reduction.

Despite the caveats, the study offers a new perspective on alcohol harm reduction. It highlights a potential avenue for individuals seeking to lower their alcohol intake. As the market for these beverages grows, understanding their role in consumer behavior becomes increasingly important for public health officials.

The study, “The Exploration of Cannabis Beverage Substitution for Alcohol: A Novel Harm Reduction Strategy,” was authored by Jessica S. Kruger, Nicholas Felicione, and Daniel J. Kruger.