Month: June 2021

As of June 2022, 37 US states have passed medical cannabis laws and 19 states have legalized recreational cannabis. Cannabis has proven beneficial for a range of conditions such as childhood seizure disorders, nausea, vomiting, and loss of appetite in people with HIV/AIDs.

In the meantime, a new generation of cannabis products has exploded onto the scene, driven by marketing that fuels a multibillion-dollar industry. The average content of THC (tetra-9-tetrahydrocannabinol, the psychoactive and potentially addictive chemical in cannabis) in smoked whole-plant products has risen from 1% to 4% in the 1970s to 15% to 30% from today’s cannabis dispensaries. Edibles and vapes may contain even higher concentrations of THC.

While public perception that cannabis is a harmless substance is growing, the long-term benefits and risks of cannabis use remain unclear. However, one consistent pattern of research has emerged: heavy long-term cannabis use can impact midlife cognition.

New research on cannabis use and cognition in midlife

Recent research published in The American Journal of Psychiatry closely followed nearly 1,000 individuals in New Zealand from age 3 to age 45 to understand the impact of cannabis use on brain function. The research team discovered that individuals who used cannabis long-term (for several years or more) and heavily (at least weekly, though a majority in their study used more than four times a week) exhibited impairments across several domains of cognition.

Long-term cannabis users’ IQs declined by 5.5 points on average from childhood, and there were deficits in learning and processing speed compared to people that did not use cannabis. The more frequently an individual used cannabis, the greater the resulting cognitive impairment, suggesting a potential causative link.

The study also found that people who knew these long-term cannabis users well observed that they had developed memory and attention problems. The above findings persisted even when the study authors controlled for factors such as dependence on other drugs, childhood socioeconomic status, or baseline childhood intelligence.

The impact of cannabis on cognitive impairment was greater than that of alcohol or tobacco use. Long-term cannabis users also had smaller hippocampi (the region of the brain responsible for learning and memory). Interestingly, individuals who used cannabis less than once a week with no history of developing dependence did not have cannabis-related cognitive deficits. This suggests there is a range of recreational use that may not lead to long-term cognitive issues.

More studies are needed on cannabis use and brain health

The new research is just one of several studies suggesting there is a link between long-term heavy cannabis use and cognition. Still, future studies are needed to establish causation and explore how long-term cannabis use might impact the risk of developing dementia, since midlife cognitive impairment is associated with higher rates of dementia.

What should you do if you experience cognitive effects of cannabis?

Some people who consume cannabis long-term may develop brain fog, lowered motivation, difficulty with learning, or difficulty with attention. Symptoms are typically reversible, though using products with higher THC content may increase risk of developing cognitive symptoms.

Consider the following if you are experiencing cannabis-related cognitive symptoms:

• Try a slow taper. Gradually decrease the potency (THC content) of cannabis you use or how frequently you use it over several weeks, especially if you have a history of cannabis withdrawal.
• Work with your doctor. Be open with your doctor about your cognitive symptoms, as other medical or psychiatric factors may be at play. Your doctor can also help you navigate a cannabis taper safely, and potentially more comfortably, using other supportive means. Unfortunately, most patients are not comfortable talking with their doctors about cannabis use.
• Give it time. It may take up to a month before you experience improvements after reducing your dose, as cannabis can remain in the body for two to four weeks.
• Try objective cognitive tracking. Using an app or objective test such as the mini-mental status exam to track your brain function may be more accurate than self-observation. Your mental health provider may be able to assist with administering intermittent cognitive assessments.
• Consider alternative strategies. Brain function is not static, like eye color or the number of toes on our feet. Aerobic exercise and engaging in mindfulness, meditation, and psychotherapy may improve long-term cognition.

Cannabis is an exciting yet controversial topic that has drawn both hype and skepticism. It is important for individuals and healthcare professionals to place emphasis on research studies and not on speculation or personal stories. Emerging studies suggesting the connection between long-term heavy use of cannabis and neurocognition should raise concern for policymakers, providers, and patients.

About the Authors

Kevin Hill, MD, MHS, Contributor

Dr. Kevin Hill is director of addiction psychiatry at Beth Israel Deaconess Medical Center, and an associate professor of psychiatry at Harvard Medical School. He earned a master’s in health science at the Robert Wood Johnson … See Full Bio View all posts by Kevin Hill, MD, MHS

Michael Hsu, MD, Guest Contributor

Dr. Michael Hsu is a resident psychiatrist and is currently the chief resident of outpatient psychiatry at Brigham and Women's Hospital, a teaching hospital of Harvard Medical School. After graduating from the University of Pennsylvania with … See Full Bio View all posts by Michael Hsu, MD

Weight stigma, as defined in a recent BioMed Central article, is the “social rejection and devaluation that accrues to those who do not comply with prevailing social norms of adequate body weight and shape.” Put simply, weight stigma is a form of discrimination based on a person’s body weight.

The authors of this article assert that weight stigma can trigger changes in the body, such as increased cortisol levels, that lead to poor metabolic health and increased weight gain. In addition, those with higher body weight may cope with weight stigma by increasing alcohol and substance use, overeating to deal with negative emotions, and avoiding health care settings or social encounters. The subsequent negative health outcomes are a result of what they call chronic social stress, and studies have found the harmful effects of weight discrimination resulted in a 60% increased risk of death, even when body mass index (BMI) was controlled for.

What can be done to combat weight stigma?

There are many ways to address weight stigma. The first is to acknowledge that it exists, since we cannot combat something if we do not first acknowledge it.

Another step we can take is to make changes in the way we think and speak about people who have excess weight. One important way to do this is to remove the word “obese” from our vocabularies. When referring to someone who has excess weight, we should aim to keep in mind that they are a person with a disease, and strive to identify them as a person instead of as the disease they have. For example, the phrase “person with obesity” should be used instead of “obese person.” This way of speaking is called using person-first language.

Addressing weight stigma in health care settings

The health care setting is one in which weight stigma is particularly rampant, leading to significant health consequences for people with overweight or obesity. Studies have shown that physicians show strong anti-fat bias in health care situations. This bias results in reduced quality of care, and is yet another way in which weight stigma contributes to poor health in people with overweight and obesity.

Just as in everyday situations, there are many ways to address stigma in health care settings. Clinicians should of course follow the same recommendations as above, to acknowledge the existence of weight stigma and strive to use person-first language in their speech and medical documentation.

In addition, dispensing with the standard cookie-cutter advice to eat less and exercise more to lose weight would be of great benefit to patients. This type of advice doesn’t take into account the many environmental, genetic, and physiologic causes of obesity, and puts blame on the patient as the sole cause and contributor of their obesity.

Clinicians should also take care not to assume a patient with obesity is automatically engaging in overeating behaviors, and should believe their patients’ reports of dietary intake and physical activity. The clinical visit should be focused on information gathering and understanding of a patient's particular situation. Referral to an obesity specialist may be warranted if the clinician is not comfortable with discussing or prescribing different treatment options.

It is of utmost importance for patients with obesity to seek care from compassionate and knowledgeable health care providers, to optimize the quality of their care and reduce the negative effects of weight bias.

Where to go for more information and resources

The following organizations have plenty of information and resources for both patients and health care providers to learn more about obesity as a disease and how to combat weight stigma.

The Obesity Action Coalition is an organization that works to help individuals with obesity improve their health through education, advocacy, awareness, and support.

The Obesity Medicine Association has a search tool to find a clinician who is board-certified in obesity medicine within a specific geographic area.

The American Society for Metabolic and Bariatric Surgery has information for those with severe obesity, or with milder obesity and other medical complications, who are interested in bariatric surgery.

About the Author

Chika Anekwe, MD, MPH, Contributor

Chika V. Anekwe, MD, MPH is an obesity medicine physician at Massachusetts General Hospital (MGH) Weight Center and Instructor in Medicine at Harvard Medical School (HMS). Her professional interests are in the areas of clinical nutrition, … See Full Bio View all posts by Chika Anekwe, MD, MPH