The effects of chronic marijuana use on the brain may depend on age of first use and duration of use, according to researchers at the Center for BrainHealth at The University of Texas at Dallas.

In a paper published today in Proceedings of the National Academy of Sciences (PNAS), researchers for the first time comprehensively describe existing abnormalities in brain function and structure of long-term marijuana users with multiple magnetic resonance imaging (MRI) techniques. Findings show chronic marijuana users have smaller brain volume in the orbitofrontal cortex (OFC), a part of the brain commonly associated with addiction, but also increased brain connectivity.

“We have seen a steady increase in the incidence of marijuana use since 2007,“said Dr. Francesca Filbey, Associate Professor in the School of Behavioral and Brain Sciences at the University of Texas at Dallas and Director of the Cognitive Neuroscience Research in Addictive Disorders at the Center for BrainHealth. “However, research on its long-term effects remains scarce despite the changes in legislation surrounding marijuana and the continuing conversation surrounding this relevant public health topic.”

The research team studied 48 adult marijuana users and 62 gender- and age-matched non-users, accounting for potential biases such as gender, age and ethnicity. The authors also controlled for tobacco and alcohol use. On average, the marijuana users who participated in the study consumed the drug three times per day. Cognitive tests show that chronic marijuana users had lower IQ compared to age-and gender-matched controls but the differences do not seem to be related to the brain abnormalities as no direct correlation can be drawn between IQ deficits and OFC volume decrease.

What’s unique about this work is that it combines three different MRI techniques to evaluate different brain characteristics,” said Dr. Sina Aslan, founder and president of Advance MRI, LLC and adjunct assistant professor at The University of Texas at Dallas. “The results suggest increases in connectivity, both structural and functional that may be compensating for gray matter losses. Eventually, however, the structural connectivity or ‘wiring’ of the brain starts degrading with prolonged marijuana use.

Tests reveal that earlier onset of regular marijuana use induces greater structural and functional connectivity. Greatest increases in connectivity appear as an individual begins using marijuana. Findings show severity of use is directly correlated to greater connectivity.

Although increased structural wiring declines after six to eight years of continued chronic use, marijuana users continue to display more intense connectivity than healthy non-users, which may explain why chronic, long-term users “seem to be doing just fine” despite smaller OFC brain volumes, Filbey explained.

“To date, existing studies on the long-term effects of marijuana on brain structures have been largely inconclusive due to limitations in methodologies,” said Dr. Filbey. “While our study does not conclusively address whether any or all of the brain changes are a direct consequence of marijuana use, these effects do suggest that these changes are related to age of onset and duration of use.”

The study offers a preliminary indication that gray matter in the OFC may be more vulnerable than white matter to the effects of delta-9-tetrahydrocannabinol (THC), the main psychoactive ingredient in the cannabis plant. According to the authors, the study provides evidence that chronic marijuana use initiates a complex process that allows neurons to adapt and compensate for smaller gray matter volume, but further studies are needed to determine whether these changes revert back to normal with discontinued marijuana use, whether similar effects are present in occasional marijuana users versus chronic users and whether these effects are indeed a direct result of marijuana use or a predisposing factor.

The research was funded by the National Institute on Drug Abuse to Dr. Filbey (R01 DA030344, K01 DA021632).

Source: Center for Brain Health

Cannabis Strains

Study Finds Patients Report Subjective Relief, Satisfaction from Different Strains of Medical Cannabis

In a study, the majority of patients prescribed medical cannabis reported that they experienced therapeutic relief from the plant, regardless of the strain they consumed.

Investigators at the Netherlands Institute of Mental Health and Addiction assessed patients’ therapeutic satisfaction with pharmaceutical-grade cannabis and compared the effects of several different strains of the marijuana plant. The study included 102 patients who consumed one of three differing types of cannabis dispensed by the Netherlands Office of Medicinal Cannabis. Investigators evaluated strains with varying levels of THC. Strains were either high in THC, with 19 percent, low in THC, with 12 percent, or contained relatively equal percentages of both THC and cannabidiol. Chronic pain was the most prevalent medical indication, followed by multiple sclerosis (MS).

According to data from the survey, patients experienced relatively equal satisfaction from cannabis across strains and consumed approximately equal doses of cannabis, regardless of the levels of THC or CBD. The type of cannabis used mostly influenced patients’ subjective feelings of anxiety, appetite, and/or feelings of dejection. Results showed that medicinal cannabis offers therapeutic relief for various conditions, many of which are characterized by chronic pain. Therapeutic satisfaction was independent of which strain of medicinal cannabis used, which is in agreement with several previous studies describing the therapeutic efficacy of cannabis products against pain, particularly neuropathic pain.

Investigators noted that the different ways of cannabis administration may have contributed to different subjective (adverse) effects. Most of the participants in the study inhaled the product, which generally produces a stronger high but also more dizziness, irritability, feelings of depression, stronger feelings of dependence, and withdrawal, among others, according to the study.

“In summary, the present results present a unique insight into a previously unstudied population of Dutch consumers of a pharmaceutically cultivated product, which has continuously raised both interest and controversy in the clinical community. It seems that this unique array of pharmaceutical cannabis products has a high therapeutic satisfactory profile within this group of patients. It largely confirms earlier findings that chronic pain and neuropathic pain are alleviated to the patient’s satisfaction. Interestingly, the pharmacologic composition of the different strains available affected the extent of different subjective (adverse) effects, with a high-THC/low-CBD product leading to more appetite stimulation but also to feelings of dejection and anxiety in comparison with low-THC/high-CBD product. The results of this study may aid medical practitioners and patients alike in selecting which strain of pharmaceutical cannabis could be most suited for their particular condition. It also contributes to a growing insight into the various effects of cannabinoids in general.”

Source: Therapeutic satisfaction and subjective effects of different strains of pharmaceutical-grade cannabis,” appears in the Journal of Clinical Psychopharmacology.


National Association of Cannabis Pharmacy Launches

The National Association of Cannabis Pharmacy (NACP) launched today during the Specialty Pharmacy EXPO, hosted by the National Association of Specialty Pharmacy (NASP), in Tampa.


The purpose of the new association is to support pharmacists who dispense, administer and compound cannabis-based products to treat specialty diseases including multiple sclerosis, HIV, oncology and Rheumatoid arthritis.


“The focus has to be on the patient and how they are receiving guidance and education to manage conditions in which medical marijuana is incorporated as part of the treatment plan,” Joseph Friedman RPh., MBA said. “There is an immediate need for the development of advanced training and parameters for pharmacists to lead the process.”


Initially, the NACP will focus on building an educational platform focused on the compounding, administration and use of medical marijuana for specialty therapeutic categories. Through the NACP, pharmacists will receive the necessary training to utilize cannabis for concomitant therapy, specifically in the retail channel. NACP will also investigate the development of an accreditation program for pharmacies and a professional certification program for pharmacists.


“The legislation guiding the use of medical marijuana varies by state and does not include the pharmacist in a role that allows them to use their knowledge and expertise to protect the patient and improve their outcomes,” Mathew Sherwood, NACP Cannabis Industry Consultant, said. “This is an opportunity to close that gap.”


Source: National Association of Cannabis Pharmacy (NACP)

Last updated: 4/8/14; 4:20pm EST