Researchers report that the acute use of cannabinoids depresses motor neuron activity

February 23rd, 2015 in Neuroscience

Enlarge

The researchers of the NeuroDegeneration and NeuroRepair Group of the University of Cadiz.

Why does the habitual marijuana user have difficulties speaking, breathing or swallowing food? Is it true that people who use marijuana may suffer acute lack of motor coordination? Does the use of cannabis cause muscular weakness? The answers to these and other similar questions are explored by the researchers of the NeuroDegeneration and NeuroRepair Group of the University of Cadiz, directed by professor Bernardo Moreno, and who recently published a study related to this topic in the prestigious journal Neuropharmacology.

This study reveals that synthetic analogues of the psychoactive compounds of marijuana significantly reduce the activity of motor neurons. To fully understand the importance of this discovery, it is necessary to bear in mind that up until now there were no studies focusing on this subject. All the work known to date related to cannabis and its effects had been based on the psychomotor mechanisms (the higher central nervous system) and there was no study focused on describing the direct impact of cannabinoids on the motor neurons that control the muscles. Therefore, the researchers decided to work on this topic using the motor hypoglossal nucleus that controls the movements of the tongue as a model, given that "the tongue is an important muscle used in respiratory phenomena, including speech and swalling food.

Thus, "during the investigation, we used an animal model in which we studied the alterations produced by synthetic cannabinoids on the activity of the motor neurons of the hypoglossal nucleus. In doing so, we discovered that these psychoactive compounds inhibit the information that reaches these neurons via the synapses (structures specialized in the communication of information between neurons). In other words, cannabinoids hinder the transmission of information between neurons." One consequence of this fact is that muscular weakness is produced as "the motor neuron, that is the one that gives the order to the muscle to contract, sees its activity reduced which, as a consequence, would weaken the strength of the muscle contraction," says Moreno. All of this could lead to problems speaking, breathing and even swallowing food.

Nevertheless, this action mechanism could also explain the beneficial therapeutic effects that marijuana has on motor disturbances in people suffering from neurodegenerative diseases such as multiple sclerosis for example, since "in pathological processes associated with muscular hyperactivity phenomena, the reduction in motor neuron activity induced by cannabis could lead to a symptomatological improvement." 

This study, carried out after studies on synaptic mechanisms performed by this group at the University of Cadiz, opens a new avenue of research for the scientific community. In spite of this, "our work will be steered towards other territories. At this time, we are in the middle of a study focusing on the effects of cannabinoids as possible mediators of synaptic plasticity (phenomenon involved in motor learning), although it must be made clear that these compounds are not the central theme of the work of our research group," concludes Moreno.

More information: García Morales, Victoria; Montero, Fernando; Moreno López, Bernardo: "Cannabinoid agonists rearrange synaptic vesicles at excitatory synapses and depress motor-neuron activity in vivo".Neuropharmacology. (2015) DOI: 10.1016/j.neuropharm.2014.12.036

Provided by Universidad de Cádiz

"Researchers report that the acute use of cannabinoids depresses motor neuron activity." February 23rd, 2015. 
http://medicalxpress.com/news/2015-02-acute-cannabinoids-depresses-motor-neuron.html

How cannabis use affects people with Bipolar Disorder

March 13th, 2015 in Psychology & Psychiatry

Enlarge

Bipolar disorder is characterized by transitions between depression and mania. Credit: Wikipedia

The first study to examine the use of cannabis in the context of daily life among people with Bipolar Disorder has shown how the drug is linked to increases in both manic and depressive symptoms.

Around 2% of the UK population has Bipolar Disorder, with up to 60% using cannabis at some point in their lives, but research in this area is limited and reasons for high levels of use are unclear.

Dr Elizabeth Tyler of the Spectrum Centre for Mental Health Research at Lancaster University led the study published in PLOS ONE with Professor Steven Jones and colleagues from the University of Manchester, Professor Christine Barrowclough, Nancy Black and Lesley-Anne Carter.

She said: "One theory that is used to explain high levels of drug use is that people use cannabis to self-medicate their symptoms of bipolar disorder. " The study looked at people diagnosed with bipolar disorder but who were not experiencing a depressive or manic episode during the six days the research was carried out.

Each participant completed a paper diary about their emotional state and drug use at several random points daily over a period of week. This enabled people to log their daily experiences in the moment before they forgot how they were feeling.

An individual with experience of bipolar disorder and cannabis use commented: "I do smoke a small amount to lift my mood and make myself slightly manic but it also lifts my mood and switches me into a different mind-set".

"I do not use weed to manage depression as it can make it worse, making me anxious and paranoid".

"I have found though that if I have smoked more excessively it can make me feel depressed for days afterwards".

The study found that the odds of using cannabis increased when individuals were in a good mood. Cannabis use was also associated with an increase in positive mood, manic symptoms and paradoxically an increase in depressive symptoms, but not in the same individuals.

Dr Tyler said: "The findings suggest that cannabis is not being used to self-medicate small changes in symptoms within the context of daily life. However, cannabis use itself may be associated with both positive and negative emotional states. We need to find out whether these relationships play out in the longer term as this may have an impact on a person's course of bipolar disorder."

More information: The Relationship between Bipolar Disorder and Cannabis Use in Daily Life: An Experience Sampling Study by Elizabeth Tyler, Steven Jones, Nancy Black, Lesley-Anne Carter, Christine Barrowclough , Published: March 4, 2015, DOI: 10.1371/journal.pone.0118916 . http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118916

Provided by Lancaster University

"How cannabis use affects people with Bipolar Disorder." March 13th, 2015. http://medicalxpress.com/news/2015-03-cannabis-affects-people-bipolar-disorder.html

Cannabis consumers show greater susceptibility to false memories

April 21st, 2015 in Psychology & Psychiatry

Enlarge

Brain activation pattern which permits ruling out a stimulus as a false memory. In the control group, the activations are much more intense and extensive than in the group of cannabis consumers. Credit: Hospital Sant Pau

A new study published in the American journal with the highest impact factor in worldwide, Molecular Psychiatry, reveals that consumers of cannabis are more prone to experiencing false memories. The study was conducted by researchers from the Human Neuropsychopharmacology group at the Biomedical Research Institute of Hospital de Sant Pau and from Universitat Autònoma de Barcelona, in collaboration with the Brain Cognition and Plasticity group of the Bellvitge Institute for Biomedical Research (IDIBELL - University of Barcelona). One of the known consequences of consuming this drug is the memory problems it can cause. Chronic consumers show more difficulties than the general population in retaining new information and recovering memories. The new study also reveals that the chronic use of cannabis causes distortions in memory, making it easier for imaginary or false memories to appear.

On occasions, the brain can remember things that never happened. Our memory consists of a malleable process which is created progressively and therefore is subject to distortions or even false memories. These memory "mistakes" are seen more frequently in several neurological and psychiatric disorders, but can also be observed in the healthy population, and become more common as we age. One of the most common false memories we have are of situations from our childhood which we believe to remember because the people around us have explained them to us over and over again. Maintaining an adequate control over the "veracity" of our memories is a complex cognitive task which allows us to have our own sense of reality and also shapes our behaviour, based on past experiences.

In the study published in the journal Molecular Psychiatry, researchers from Sant Pau and Bellvitge compared a group of chronic consumers of cannabis to a healthy control group while they worked on learning a series of words. After a few minutes they were once again shown the original words, together with new words which were either semantically related or unrelated. All participants were asked to identify the words belonging to the original list. Cannabis consumers believed to have already seen the semantically related new words to a higher degree than participants in the control group. By using magnetic resonance imaging, researchers discovered that cannabis consumers showed a lower activation in areas of the brain related to memory procedures and to the general control of cognitive resources.

The study found memory deficiencies despite the fact that participants had stopped consuming cannabis one month before participating in the study. Although they had not consumed the drug in a month, the more the patient had used cannabis throughout their life, the lower the level of activity in the hippocampus, key to storing memories.

The results show that cannabis consumers are more vulnerable to suffering memory distortions, even weeks after not consuming the drug. This suggests that cannabis has a prolonged effect on the brain mechanisms which allow us to differentiate between real and imaginary events. These memory mistakes can cause problems in legal cases, for example, due to the effects the testimonies of witnesses and their victims can have. Nevertheless, from a clinical viewpoint, the results point to the fact that a chronic use of cannabis could worsen problems with age-related memory loss.

Provided by Universitat Autonoma de Barcelona

"Cannabis consumers show greater susceptibility to false memories." April 21st, 2015. 
http://medicalxpress.com/news/2015-04-cannabis-consumers-greater-susceptibility-false.html

Cannabis psychosis, gender matters

July 22, 2015 in Medicine & Health / Psychology & Psychiatry

There has been much research exploring the nature of the relationship between cannabis and psychosis, however the role of gender in relation to cannabis psychosis is less well explored and understood.

Department of Health Sciences' researchers Ian Hamilton, Paul Galdas and Holly Essex used large datasets over a period of 11 years to investigate the differences in men and women as they progress from exposure to cannabis through to developing cannabis psychosis.

Cannabis is the most widely used illicit drug in the United Kingdom. Trends in cannabis use suggest that twice as many males as females use the drug. This gender ratio is mirrored in rates of psychosis with males outnumbering females by 2:1. However there is a significant widening of this ratio for cannabis psychosis, where males outnumber females by four to one.

"The marked gender difference in rates of cannabis psychosis is puzzling," said Ian. "It is possible that mental health and specialist drug treatment services, which have a disproportionate number of men, are identifying and treating more males with combined mental health and cannabis problems.

"However it is also possible that women with cannabis psychosis are not being identified and offered treatment for the problems they develop.

"When it comes to cannabis psychosis gender does matter."

More information: Advances in Dual Diagnosis Volume 8, Issue 3 
www.emeraldinsight.com/doi/abs/10.1108/ADD-12-2014-0039 

Provided by University of York

"Cannabis psychosis, gender matters" July 22, 2015 
http://medicalxpress.com/news/2015-07-cannabis-psychosis-gender.html

Cannabis use may influence cortical maturation in adolescent males

August 26, 2015 in Medicine & Health / Psychology & Psychiatry

Male teens who experiment with cannabis before age 16, and have a high genetic risk for schizophrenia, show a different brain development trajectory than low risk peers who use cannabis.

The discovery, made from a combined analysis of over 1,500 youth, contributes to a growing body of evidence implicating cannabis use in adolescence and schizophrenia later in life.

The study was led by Baycrest Health Sciences' Rotman Research Institute in Toronto and is reported in JAMA Psychiatry today, ahead of print publication.

Adolescence is a period of vulnerability with regard to the emergence of psychotic disorders, especially in boys. Environmental influences on the continuing maturation of neural circuits during adolescence are of great interest to neuroscientists and medical professionals.

"Given the solid epidemiologic evidence supporting a link between cannabis exposure during adolescence and schizophrenia, we investigated whether the use of cannabis during early adolescence (by 16 years of age) is associated with variations in brain maturation as a function of genetic risk for schizophrenia," said senior author Tomas Paus, MD, PhD, the Anne and Max Tanenbaum Professor and Chair in Population Neuroscience at Baycrest, University of Toronto, and the Dr. John and Consuela Phelan Scholar at Child Mind Institute, New York.

"Our findings suggest that cannabis use might interfere with the maturation of the cerebral cortex in male adolescents at high risk for schizophrenia by virtue of their polygenic risk score. Their brains showed lower cortical thickness compared with low-risk male participants and low-or-high risk female participants who used the drug."

Dr. Paus, a prominent researcher and pioneer in the field of population neuroscience, strongly cautioned that more research is needed to determine whether lower cortical thickness actually increases the probability of schizophrenia in at-risk males later in life.

The research team used observations from three large samples of typically developing youth in Canada and Europe. Researchers examined data from a total of 1,577 participants (aged 12 - 21 years, 57% male / 43% female), that included information on cannabis use, brain imaging results, and polygenic risk score for schizophrenia. The data came from the Saguenay Youth Study in Quebec (Canada), the Avon Longitudinal Study of parents and Children in the U.K., and the IMAGEN Study in the U.K., Germany, France and Ireland.

According to the National Alliance on Mental Illness: "It is too early to classify schizophrenia as either a neurodevelopmental (impairment of the growth and development of the brain) or a neurodegenerative (progressive loss of structure or function of neurons) disorder, as both seem to occur over the course of the illness. Research strongly suggests the emergence of schizophrenia is a result of both genetic and environmental factors."

"Brain aging is about brain development," said Dr. Paus. "Our study shows the importance of understanding environmental influences on the developing brain in early life as this can have important implications for brain health through the lifespan."

More information: JAMA Psychiatry. Published online August 26, 2015. DOI: 10.1001/jamapsychiatry.2015.1131 

Provided by Baycrest Centre for Geriatric Care

"Cannabis use may influence cortical maturation in adolescent males" August 26, 2015 
http://medicalxpress.com/news/2015-08-cannabis-cortical-maturation-adolescent-males.html

What Marijuana Does to Your Metabolism

Posted: 09 Sep 2015 03:03 AM PDT

The effects of marijuana use are wide-ranging. Some strains make you feel sleepy and relaxed, others make you feel energetic and creative; but one of the most universal effects of getting stoned is acute, unremitting hunger. It is a phenomenon known as "the munchies," and though it is commonly associated with late night, high-calorie diets, recent studies suggest that the relationship between cannabis use and the human metabolic system is more complex than it might seems.

In fact, the rate of obesity and diabetes among weed smokers is dramatically reduced compared to non-marijuana users, researchers found. Also, frequent marijuana users are generally slimmer than non-users, with waistlines that are 1.5 inches smaller, on average, than their former or non-using counterparts.

After surveying 786 adults in an Inuit community—where more than half of the indigenous population reported frequent cannabis use—researchers at Université Laval in Quebec, Canada, determined that smoking pot statistically correlated with lower body mass index (BMI), lower fat percentages, and lower fasting insulin levels.

Published in the journal Obesity earlier this year, the study's findings support what several other research institutions have found regarding the effects of marijuana on metabolism. In 2013, the American Journal of Science released a report that also noted the low prevalence of obesity in cannabis users despite an abundance of empirical and anecdotal evidence linking stoners to high caloric diets.

"The most important finding is that current users of marijuana appeared to have better carbohydrate metabolism than nonusers," Murray Mittleman, an associate professor of medicine at Harvard Medical School and the lead author of the study, told Time. "Their fasting insulin levels were lower, and they appeared to be less resistant to the insulin produced by their body to maintain a normal blood-sugar level."

In that study, researchers analyzed data reported by more than 4,600 people participating in the National Health and Nutrition Examination Survey—48 percent of whom had used cannabis at least once and 12 percent reported they were active users at the time of the survey—and what they discovered seemed to defy explanation. Current marijuana users had 16 percent lower fasting insulin levels than former and non-users; they also showed, on average, 17 percent reduction in insulin resistance.

Remarkably, population-based data from these reports also indicate that regular marijuana users are about 30 percent less likely to develop Type 2 diabetes. So even though smoking pot might give you the munchies, rending you defenseless against a bag of Doritos (as the cliche would have it, at least), rates of obesity and diabetes are reduced nonetheless among stoners.

"Cannabis smoking may also result in similarly increased energy expenditure as with cigarette smoking," Michel Lucas, an epidemiologist at Université Laval, told:. "In fact, cannabis smoking directly increases heart rate and blood pressure for several hours, as with tobacco."

"[It would] be very interesting to see if the cannabis effect is the same when you eat or smoke it," he added.

Courtesy: ATTN

Cannabis increases the noise in your brain

December 3, 2015 in Medicine & Health / Psychology & Psychiatry 

Cannabis indica. Credit: Wikipedia

Several studies have demonstrated that the primary active constituent of cannabis, delta-9-tetrahydrocannabinol (∆9-THC), induces transient psychosis-like effects in healthy subjects similar to those observed in schizophrenia. However, the mechanisms underlying these effects are not clear.

A new study, published in the journal Biological Psychiatry, reports that ∆9-THC increases random neural activity, termed neural noise, in the brains of healthy human subjects. The findings suggest that increased neural noise may play a role in the psychosis-like effects of cannabis.

"At doses roughly equivalent to half or a single joint, ∆9-THC produced psychosis-like effects and increased neural noise in humans," explained senior author Dr. Deepak Cyril D'Souza, a Professor of Psychiatry at Yale School of Medicine.

"The dose-dependent and strong positive relationship between these two findings suggest that the psychosis-like effects of cannabis may be related to neural noise which disrupts the brain's normal information processing," added first author Dr. Jose Cortes-Briones, a Postdoctoral Associate in Psychiatry at Yale School of Medicine.

The investigators studied the effects of ∆9-THC on electrical brain activity in 24 human subjects who participated in a three-day study during which they received two doses of intravenous ∆9-THC or placebo in a double-blind, randomized, cross-over, and counterbalanced design.

If confirmed, the link between neural noise and psychosis could shed light on the biology of some of the symptoms associated with schizophrenia.

"This interesting study suggests a commonality between the effects on the brain of the major active ingredient in marijuana and symptoms of schizophrenia," stated Dr. John Krystal, Editor of Biological Psychiatry. "The impairment of cortical function by ∆9-THC could underlie some of the cognitive effects of marijuana. Not only does this finding aid our understanding of the processes underlying psychosis, it underscores an important concern in the debate surrounding medical and legalized access to marijuana."

More information: Jose A. Cortes-Briones et al. The Psychosis-like Effects of Δ9-Tetrahydrocannabinol Are Associated With Increased Cortical Noise in Healthy Humans, Biological Psychiatry (2015). 

DOI: 10.1016/j.biopsych.2015.03.023 

Provided by Elsevier

"Cannabis increases the noise in your brain" December 3, 2015 

http://medicalxpress.com/news/2015-12-cannabis-noise-brain.html