“Widespread use of cannabis amongst the young population makes it a public health issue.”
—Professor Andrea Cipriani, NIHR Research Professor of Psychiatry at the University of Oxford.
Dr Neil Singh, close to the end of his presentation, ‘Cannabis use and depression in young adults’, summed up the potential effects of marijuana use with the above quote. Head of the Health Services Unit, The University of the West Indies (UWI), St Augustine Campus, he, in a panel of six, presented at the Catholic Commission of Social Justice’s virtual symposium, ‘Marijuana and cannabinoids: Health, research and regulatory considerations’ on June 7.
Brain development and the young user
An OAS Inter-American Drug Abuse controlled commission study, CCAD, in 2010 indicated substance abuse began at the age of 13 across Caribbean countries. Dr Singh added later that peak usage occurred in the 17–25 age group.
In an earlier presentation, ‘Marijuana and risk-taking behaviours’, Dr Christine Descartes, lecturer in Psychology in the Department of Behavioral Sciences at UWI, St Augustine Campus said: “The literature tells us, that the brain remains in a state of constant neuro-development up until approximately 25 years.” All presenters acknowledged diminishing cognitive skills with early and frequent use, and the need for greater research.
Dr Ian Hypolite, Medical Doctor and Psychiatrist, St Ann’s Mental Hospital, in ‘The effects of cannabis on the young brain’ detailed the various parts of the brain affected. Cannabinoid receptors, he said, are widely distributed throughout the brain, and are located mainly in the hippocampus and the pre-frontal cortex, important parts of the brain. One study indicated that there was volume decline in the hippocampus which is responsible for memory, and in the pre-frontal cortex, responsible for executive functioning.
The amygdala, the seat of emotion, saw an increase in volume, indicating emotional involvement in the use of cannabis. Both grey and white matter were also affected.
With regard to white matter, Dr Hypolite made the analogy of computer processing speeds. “In respect of performance on tasks that tested attention, working memory, and processing speed, it was noted that white matter, was impacted, and led to impairment in these particular parameters, with young cannabis users.”
Cannabis use can also impact negatively on the amount of grey matter. Ultimately, with both white and grey matter affected, there may be alterations in the cannabinoid receptor systems that may lead to neurochemical or neurostructural abnormalities and consequently to poor cognition and emotional outcomes later on in adulthood.
Impact on the young adult
Dr Singh clarified the term ‘marijuana use’ in terms of impact, explaining that variables with regard to concentration in the type of marijuana and frequency had to be taken into consideration.
‘Skunk’ for example, had a 14 per cent concentration of Tetrahydrocannabinol (THC). It was also important to note that the effects described in past studies, are most likely negatively greater, due to genetic modification which has increased the psychoactive compound.
Especially vulnerable are the “marijuana naives” who may consume large amounts of high-potency marijuana and who can develop psychosis. “People who use skunk (14 to 15 per cent THC) on a daily basis have a five times greater ratio of having a psychotic episode.
Cannabis, Dr Hypolite said, can be many things: a stimulant, a depressant, a hallucinogen, and it can be different things to different people. “We have all been aware of people who have developed psychosis…so they may develop hallucinations, in any of the five sentry modalities [the five senses], delusions….”
These he explained, are consistent with symptoms of schizophrenia spectrum illness but what is not known is whether marijuana usage had actually caused the psychosis. “….but given a particular situation, or particular environment, and for example genetic vulnerability, it can produce psychotic disorder, and in some instances, induce or exacerbate schizophrenia.”
The short-term impact of marijuana usage are: effects on time perception, driving ability, increased appetite, blunted motor coordination, and reduced impulse control. In the long term, the effects can be: paranoia, panic, depression, suicide, anxiety, bipolar disorders, and cannabis use disorder. Cannabis use can also cause chronic bronchitis, emphysema, testicular cancer, and it is a possible gateway drug.
“THC primes the brain and enhances the response to other drugs….with co-existence to cocaine and alcohol,” said Dr Singh.
A large-scale study done in New Zealand in 2012, found that there was a decline in IQ with persistent cannabis dependence. Dr Singh indicated that the decline was an eight-point drop in IQ for those using cannabis from childhood to adulthood. Those who use marijuana heavily in childhood, do not recover the loss of their IQ.
With regard to permanence in cognitive changes, Dr Hypolite admitted: “As in any scientific study, there isn’t always a 100 per cent unanimous agreement….And certainly in respect of cognition, it is the same.”
He referenced a study, which showed that over an eight-year period of abstinence, “if there was initial cognitive dysfunction, then that cognitive dysfunction disappeared after a while”.
Another study showed that after three weeks, there was still an attention deficit, “but the literature on a whole from my review, showed that many of the subtle cognitive changes, may resolve after long-term abstinence.”
The big question that remained, however, according to Dr Hypolite “is what is the rate of abstinence after having initiation at an early age. In many cases, once you start early, you do not necessarily abstain after.”
Dr Singh said that the perception of the risk of marijuana use is at an all-time low. “Youths think that marijuana is harmless, which may be the result of the ongoing dialogue about possible benefits.”
There is the misconception that marijuana in its raw form will give the beneficial effects of those drugs derived by a manufacturing process, cannabidiol (CBD) extracts. —SD