Marijuana May Speed Cortical Loss in Boys at Risk for Schizophrenia
In boys, a decrease in the thickness of the cortex is a part of normal maturation. However, according to a recent study, this process is sped up in boys at high risk for schizophrenia when they use marijuana before the age of 16.
Early use of marijuana has been linked to subsequent development of schizophrenia. Schizophrenia begins about 5 years earlier in males than in females, and the male brain goes through more structural changes during adolescence.
A 2015 article by Tomáš Paus in the journal JAMA Psychiatry incorporated data from three studies, which took place in parts of Canada and England and eight European cities. The studies all included magnetic resonance imaging (MRI) scans of the participants, a measure of their genetic risk of developing schizophrenia, and questions about their past marijuana use. In boys at high risk for schizophrenia based on their genetic profile, cortical thickness dropped more among the ones who used high amounts of marijuana before the age of 16 compared to those who did not.
Paus hypothesizes that the development of schizophrenia is a “two-hit process.” People who develop schizophrenia may have an early risk factor, such as their genetic profile or a problem that occurs in utero, and a later stressor such as drug use in adolescence.
Link Between Childhood Trauma and Difficult Course of Bipolar Disorder Clarified
A collaboration between Norwegian and French researchers led by Bruno Etain has clarified the pathway by which childhood trauma is linked to worse outcomes among people with bipolar disorder. The researchers, who presented their work in a poster at the 2015 meeting of the Society of Biological Psychiatry, replicated earlier findings by this editor (Robert Post) that patients who experienced trauma as a child had a more adverse course of bipolar disorder. Etain and colleagues found a link between childhood trauma and an earlier age of onset of bipolar disorder, rapid cycling, suicide attempts, and cannabis misuse.
The researchers identified more than 550 patients with bipolar disorder, who answered questionnaires about their history of bipolar disorder and childhood trauma. Their DNA was also analyzed, and the researchers found that the effect of childhood trauma on age of onset was mediated by the presence of common genetic variants in proteins related to stress (the serotonin transporter) and immune function (Toll-like receptors). They also found that the traits of mood lability (or moodiness) and impulsivity mediated the effects of trauma on clinical outcomes.
The lasting epigenetic effects of child maltreatment and adversity noted in the above abstract are consistent with a large literature showing more epigenetic effects in these individuals than in controls. While genetics are important, the impact of the environment is also substantial.
Halting Marijuana Use Might Improve Memory
Researcher Amanda Roten reported at the 2014 meeting of the American Academy of Child and Adolescent Psychiatry that adolescents who stopped heavy marijuana use showed improvements in multiple areas of learning and memory. These data support previous findings that pot can cause impairments in cognitive functioning, but that abstaining from the drug can bring about improvement relative quickly.
These data contrast with some others. A 2009 study by J. Jacobus et al. in the journal Pharmacology Biochemistry and Behavior suggested that some changes in brain structure resulting from marijuana use, such as decreases in cortical volume, can persist for one to three months following abstinence.
Madeline Meier, another researcher at the meeting, reported that 1,037 participants who used marijuana persistently from about age 13 to age 38 lost an average of 8 IQ points. Controlling for years of education and other potential confounds such as alcohol and drug use did not affect these findings. Moreover, Meier found that “cessation of cannabis use did not fully restore IQ among adolescent-onset cannabis users.”
Editor’s Note: The popular view that marijuana is a benign substance overlooks some key facts. The main pharmacological effect of pot is an amotivational syndrome, causing apathy and lack of drive to participate in work, study, and other activities. Heavy use of pot doubles the risk of psychosis, and this risk is further increased if a user has a common genetic variation in the enzyme catechol-o-methlyl transferase (COMT), which metabolizes dopamine. The more efficient allele of COMT (known as val-56-val, identifying two valine amino acids) lowers frontal cortex dopamine more, and increases the risk of delusions and hallucinations. Marijuana alters brain structure and impairs memory. It may now be legal in some states, and while reducing penalties for smoking marijuana may be a good idea, this does not mean the drug is a harmless substance.
The moral of the story is that avoiding marijuana use in the first place, especially for people with bipolar disorder, should make it easier to get well and stay well. For current marijuana users, N-acetylcysteine (NAC, a nutritional supplement available without a prescription from health food stores) has been shown to help adolescents decrease marijuana use more than placebo.
How the Chemicals in Marijuana Work in the Brain
Raphael Mechoulam, who first synthesized THC, the main ingredient in marijuana, gave the history of marijuana and its receptors in the central nervous system in a plenary talk at the 2014 meeting of the International College of Neuropsychopharmacology. In Syria hundreds of years ago the drug was named ganzigunnu, meaning “the drug that takes away the mind.” It has also been called azalla, meaning “hand of the ghost.” Among the 100 compounds in marijuana, the best-known ingredient is delta-9-tetrahydrocannabinol (delta-9 THC), which produces most of the actions of the drug. There is another active ingredient, cannabidiol (CBD), which has calming and anti-anxiety effects, but is present in very low levels.
The brain has cannabinoid receptors that respond to ingredients in marijuana in addition to other chemicals produced in the brain. They modulate calcium ions and decrease the release of many neurotransmitters.
THC acts at CB-1 receptors, producing the high. The CB-1 receptor is synthesized on demand, post-synaptically, and is transferred to the pre-synaptic terminal where it decreases calcium and transmitter release. Consistent with marijuana’s appetite-stimulating properties (“the munchies”), if the CB-1 receptor is blocked in animals, they lose their appetite and die of hunger.
There are also low levels of CB-2 receptors in the brain, whose activation does not cause a high, and whose levels may increase dramatically in pathological situations. Activation of the CB-2 receptor is anti-inflammatory and, in the same way that the immune system acts against foreign proteins, CB-2 acts as a protector against non-proteins.
CBD does not bind to any cannabinoid receptors, but its actions are blocked by cannabinoid antagonists.
There are two chemicals in the brain (endogenous ligands) that act at cannabinoid receptors—anandamide and 2-arachidonoylglycerol (2-AG). They are soluble only in lipids (not in water), and have never been given to people. In animals, 2-AG has neuroprotective effects, decreases the size of a stroke by 60%, and increases recovery from stroke.
Marijuana and CBD in particular have also had beneficial effects in people. Marijuana decreases the nausea and vomiting associated with chemotherapy in children, has anti-inflammatory effects in rheumatoid arthritis (decreasing inflammatory marker TNF alpha), and has anti-diabetes and anti-convulsant effects.
In 2012, researcher F. Markus Leweke and colleagues showed that CBD was about as effective as the atypical antipsychotic amisulpiride in alleviating the psychotic symptoms of schizophrenia. CBD’s other effects include reducing anxiety and improving psoriasis by increasing DNA methylation (Pucci et al. 2013).
It seems possible that some of these myriad effects of marijuana and endogenous ligands at CB receptors could be exploited for clinical therapeutics, as Mechoulam endorses, but when and how that will take place remains an unanswered question.
Editor’s Note: Despite all these potential positives of CBD, it should be noted that its levels are very low in marijuana, and that heavy smoking of marijuana has substantial adverse effects. These include low motivation, a doubling of the risk of psychosis, a hastening of the onset of bipolar disorder and schizophrenia, and cognitive impairment, as well as some changes in brain structure seen via magnetic resonance imaging (MRI). It may be becoming legal in many states, but is a bad idea for those at high risk for mood, anxiety, or bipolar disorders or for schizophrenia.
Marijuana Addiction Associated with White Matter Loss and Brain Changes in Healthy People and Those with Schizophrenia
In an image from an MRI, the blue color depicts low blood volume, indicating areas of white matter.
It has been established that cannabis use is associated with impairments in working memory, but researchers are still investigating how these impairments come about. A 2013 study by Matthew J. Smith et al. in the journal Schizophrenia Bulletin compared regular marijuana users both with and without schizophrenia with demographically similar people who did not use marijuana.
Using magnetic resonance imaging (MRI), the researchers were able to map each participant’s brain structures. Healthy people who were marijuana users showed deficits in white matter (axons of neurons that are wrapped in myelin) compared to healthy people who did not use the drug. Similarly, patients with schizophrenia who used marijuana regularly had less white matter than those patients with schizophrenia who did not use the drug. There were also differences in the shapes of brain structures, including the striatum, the globus pallidus, and the thalamus, between cannabis users and non-users.
Differences in the thalamus and striatum were linked to white matter deficits and to younger age of cannabis use disorder onset.
Differences between cannabis users and non-users were more dramatic across the populations with schizophrenia than across the healthy populations.
Editors note: Future research is needed to determine whether marijuana causes these brain changes, or whether the brain changes are a biomarker that shows a vulnerability to marijuana addiction (although the latter is less likely than the former).
Other data show that marijuana is associated with an increase in psychosis (with heavy use), cognitive deficits, and an earlier onset of both bipolar disorder and schizophrenia in users compared to non-users. These findings make pot begin to look like a real health hazard. With legalization of marijuana occurring in many states, ease of access will increase, possibly accompanied by more heavy use. The most consistent pharmacological effect of marijuana is to produce an amotivational syndrome, characterized by apathy or lack of interest in social activities. Particularly for those already struggling with depression, pot is not as benign a substance as it is often thought to be.
Adolescent Brain Particularly Susceptible to Decline in IQ from Marijuana Use
A decades-long study in New Zealand suggests that people who use marijuana persistently during adolescence lose 8 IQ points by adulthood compared to their peers who never use marijuana. Quitting or reducing cannabis use after adolescence did not restore the intellectual abilities in those who used it persistently in their youth. This is the first study of its kind that controlled for differences in functioning that existed before adolescence.
Participants took part in neuropsychological testing at the age of 13, prior to any cannabis use, and then were periodically interviewed about their use of the drug (at the ages of 18, 21, 26, 32, and 38). At age 38 they underwent IQ testing again.
Although persistent cannabis users tended to have fewer years of education, the lack of education was not responsible for the difference in adult IQ.
Those participants who only began using cannabis persistently in adulthood did not see a decline in IQ, suggesting that the adolescent brain is particularly susceptible to damage from cannabis use.
Synthetic Marijuana Comes with Serious Risks, Including Risks to Fetus
Synthetic marijuana, otherwise known as spice, skank, or K2, is not only vastly more potent than the tetrahydrocannabinol (THC) in marijuana plants, but it also lacks cannabidiol (CBD), the calming, antipsychotic substance also present in the plants. This makes spice much more likely to induce major psychiatric effects.
New evidence links use
of spice during pregnancy to a tragic birth defect, anencephaly, or absence of the cerebral cortex. It can also lead to the later development of attention-deficit hyperactivity disorder, learning disabilities, memory impairment, depression, and aggression.
Effects of THC on gestation may occur as early as two weeks after conception, meaning by the time a woman realizes she is pregnant, the fetus may have been harmed by exposure to the drug.
Other new finding associate use of spice with acute coronary syndrome and the kind of acute kidney injury that can lead to the organ shutting down.
Editor’s Note: It has now been found that synthetic marijuana, or spice, can lead to psychosis, delirium, acute coronary syndrome (heart attack) in young people, and now kidney dysfunction, in addition to causing birth defects if used by pregnant women. Not only is spice made up of more potent THC without the calming effects of CBD, but it is often laced with unknown contaminants, which are likely the cause of the heart and kidney damage.
Smoking regular marijuana is bad enough—it doubles the risk of psychosis and may precipitate the onset of schizophrenia. It may also cause long-lasting effects on cognitive function. Since many states are legalizing marijuana, it is important to know the risks. In any case the risks are much more serious with the synthetic product, and synthetic marijuana should be avoided at all costs.
Psychosis Risks with Marijuana Use
At a recent conference Robin Murray, a researcher based in London, gave a talk about the potential adverse effects of tetrahydrocanabinol (THC). Considerable data indicate that chronic long-term smoking of marijuana is associated with the doubling of the risk of psychosis. Moreover, if a marijuana user has a common genetic variant in the catechol-o-methyltransferase enzyme (COMT), they are at substantially increased risk for the development of psychosis. New data also indicate that frequent use of marijuana can also be associated with an earlier onset of schizophrenic psychosis than would ordinarily occur without the substance use. Data also suggest that the psychosis associated with THC use is more difficult to treat than that without such use.
Murray also reported on a new risk that is associated with more potent new products. Older, natural forms of marijuana contained a compound called cannabidiol, which is associated with calming effects and possible antipsychotic effects. In a new synthetic preparation of THC called skank or spice, there is a higher amount of THC, but none of the positive diol compound. Thus there are some important caveats to the prevailing view that marijuana is relatively harmless.
Editor’s Note: Marijuana use brings a clear-cut increased risk for psychosis, which appears to interact with a common gene polymorphism and which is increased with use of a new synthetic preparation called skank or spice. If a marijuana user has a concurrent mood disorder, the risks appear to be even greater. The one sure pharmacological effect of marijuana is an amotivational syndrome, and motivational deficits are one of the core components of depression.
Given the difficulty of treating the mood and schizophrenic disorders, a patient should not risk worsening their illness with marijuana. N-acetylcysteine is one treatment option that may bring about decreased craving for and avoidance of marijuana and a number of other abused substances, as well as being helpful for mood and negative symptoms in schizophrenia.
