For a lot of young Nigerians, smoking cannabis (weed) — often considered a ‘soft drug’— is thought of as a rite of passage no more dangerous than taking their first sip of beer or wine.
Recently, legislation passed in several states in the United States, legalising marijuana for both medical and recreational use has only served to bolster public opinion that pot use, even regular pot use, is pretty benign and can alleviate certain health problems.
But a report commissioned by the National Academies of Sciences, Engineering and Medicine, released in mid-January, warns against the dangers of pot use, especially in adolescence.
The report cites evidence that heavy pot use, prolonged length of exposure and age at the beginning of exposure may all be risk factors in triggering a first episode of psychosis. Where mental illness, especially schizophrenia, already exists, the report concludes, heavy and prolonged pot use may make symptoms worse.
Over the past decade, multiple studies have shown that marijuana use in adolescence can be a contributing factor in triggering or worsening the symptoms of serious psychotic mental illnesses, most notably schizophrenia. But studies have also found that young people with a predisposition to developing a psychotic illness may be drawn to pot at an earlier age, possibly as a form of self-medication, than other adolescents. So it goes both ways.
The report, which assessed more than 1,000 studies, emphasised how little is still known about the health effects of marijuana, calling the lack of scientific information “a public health risk,” especially when it comes to the effects of marijuana on the developing brains of adolescents.
“We need more data,” says Michael Birnbaum, MD, a child and adolescent psychiatrist and director of the Early Treatment Program at Northwell Health.
Because Birnbaum treats early psychosis and works with young adults with schizophrenia, he notes, “inevitably pot, and drugs, and alcohol become a part of the conversation.”
Schizophrenia
The debate surrounding the link between weed smoking (cannabis use) and schizophrenia has been ongoing for decades, garnering attention from researchers, medical professionals, and the public alike.
As cannabis becomes increasingly legalised and socially accepted worldwide, understanding its potential mental health implications is crucial. Among the various concerns, the association between cannabis use and the onset of schizophrenia stands out due to its complex and potentially severe nature.
Schizophrenia is a chronic and severe mental disorder characterised by symptoms such as hallucinations, delusions, disorganised thinking, and impaired cognitive functioning. The exact cause of schizophrenia remains unclear, but it is widely accepted that a combination of genetic, environmental, and neurobiological factors contributes to its development. The disorder typically manifests in late adolescence or early adulthood, a period often marked by significant life changes and stressors.
Cannabis, commonly referred to as weed, contains numerous compounds, with delta-9-tetrahydrocannabinol being the primary psychoactive component. THC interacts with the brain’s endocannabinoid system, influencing mood, perception, and cognitive functions.
While many users consume cannabis for its relaxing and euphoric effects, it can also produce adverse reactions, including anxiety, paranoia, and psychotic symptoms, particularly at high doses, experts have noted.
Research exploring the link between cannabis use and schizophrenia has yielded compelling, albeit complex, findings.
Several studies have shown that cannabis use, especially heavy or frequent use during adolescence, is associated with an increased risk of developing schizophrenia later in life.
A meta-analysis published in the journal ‘Lancet Psychiatry’ in 2019 indicated that daily cannabis users had a threefold higher risk of developing psychotic disorders compared to non-users.
A medical practitioner, Dr Tosin Ajala, said the relationship appeared to be dose-dependent. According to her, higher THC concentrations and more frequent use are correlated with greater risks.
Additionally, individuals with a predisposition to mental health disorders, such as those with a family history of schizophrenia, are more vulnerable to the psychosis-inducing effects of cannabis.
She said, “One of the key aspects of the cannabis-schizophrenia link is the interplay between genetic and environmental factors.
“Certain genetic variants, particularly those affecting the dopamine system, may increase an individual’s susceptibility to both cannabis use and schizophrenia. Studies have shown that cannabis can trigger or exacerbate psychotic symptoms in individuals already at genetic risk for schizophrenia, suggesting a gene-environment interaction.
“Moreover, environmental factors such as early-life stress, trauma, and urban living conditions can also contribute to the development of schizophrenia and may interact with cannabis use to heighten the risk.”
A senior psychologist based in Uyo, Akwa Ibom State, Dr Usen Essien, noted that while there was strong evidence of an association between cannabis use and schizophrenia, it was crucial to differentiate between causation and correlation.
“Cannabis use alone is unlikely to cause schizophrenia in individuals without other risk factors. Instead, it is considered a contributing factor that can precipitate or worsen psychotic symptoms in predisposed individuals. The majority of cannabis users do not develop schizophrenia, indicating that multiple factors must converge for the disorder to manifest.
“The growing acceptance and legalisation of cannabis necessitates a balanced approach to its use, recognising both its potential benefits and risks. Public health campaigns should focus on educating the public, especially adolescents and those at high risk, about the potential mental health implications of cannabis use.
“The connection between weed smoking and schizophrenia is complex, involving a combination of genetic, environmental, and neurobiological factors.”
In a landmark research, a professor of clinical psychiatry at the Columbia University College of Physicians and Surgeons, Dr Michael Compton, said he conducted several studies and meta-analyses focusing on the association between first-episode psychosis and cannabis use.
The two studies Compton and his colleagues conducted involved, respectively, 109 and 247 hospitalised first-episode psychosis patients.
“Very detailed and rigorous retrospective data were collected on the onset of prodromal and psychotic symptoms, as well as the initiation and escalation of nicotine, alcohol, marijuana, and other drug use,” said Compton.
Both studies revealed an association between the escalation of marijuana use and an earlier age at the onset of prodromal symptoms and an earlier age at the onset of psychotic symptoms.
“These findings,” Compton said, “suggest that adolescent/premorbid marijuana use is not only a risk factor for the later development of primary psychotic disorders (which has been shown in prior studies) but is also a risk factor for an earlier onset of those disorders.”
Age of onset matters because studies show that the long-term outlook for a person with schizophrenia is better the later the disorder develops. Compton’s studies also fortified the idea that age at onset is “a crucial prognostic indicator for the long-term course of schizophrenia and other psychotic disorders.”
Link with psychosis
The connection between cannabis use and psychosis is a topic of increasing concern, especially as cannabis becomes more widely used and accepted globally.
In Nigeria, the growing use of cannabis, particularly among young people, has raised alarms about its potential mental health implications.
Psychosis is a mental health condition characterized by a disconnection from reality, manifesting as hallucinations, delusions, and impaired thinking.
Conditions like schizophrenia often involve psychotic symptoms. The onset of psychosis is typically influenced by a combination of genetic, environmental, and neurobiological factors.
Research has consistently shown a link between cannabis use and an increased risk of developing psychosis.
The risk was even higher for those using high-potency cannabis. This association is particularly concerning for adolescents and young adults, whose brains are still developing and are more vulnerable to the drug’s effects.
A resident psychiatrist based in the United States, Peju Emmanuel-Kofo, said the relationship between cannabis and psychosis was complex, involving both genetic and environmental factors.
According to her, certain genetic variants, particularly those affecting the dopamine system, may increase susceptibility to both cannabis use and psychosis.
“Cannabis use can trigger or exacerbate psychotic symptoms in genetically predisposed individuals.
“Additionally, environmental factors such as early-life stress, trauma, and urban living conditions can interact with cannabis use to heighten the risk,” she noted.
In Nigeria, several ratings noted that cannabis was the most widely used illicit drug.
According to the National Drug Use Survey in 2020, approximately 10.8 per cent of the population, or 10.6 million people, reported using cannabis.
In 2024, an estimated 20.8 million people in Nigeria use cannabis, making it the country with the highest rate of cannabis consumption globally. This represents about 19.4% of Nigeria’s population over the age of 15. Despite its illegal status, the cannabis market in Nigeria is valued at approximately $15.3 billion annually, according to the National Bureau of Statistics.
The survey also indicated that cannabis use is more prevalent among young adults aged 25 to 39.
This widespread use, coupled with the high-potency strains available, raises significant concerns about mental health impacts, particularly psychosis.
Nigeria faces unique challenges regarding mental health care, including limited access to services, stigma, and inadequate funding. The rising use of cannabis and its potential link to psychosis exacerbate these challenges, placing additional strain on the healthcare system.
Emmanuel-Kofo added, “Addressing the issue of cannabis use and psychosis in Nigeria requires a multi-faceted approach. Public health campaigns should focus on educating the population, especially young people, about the risks of cannabis use. Schools and community organisations can play a crucial role in spreading awareness and promoting healthy lifestyles.
“Moreover, improving mental health services and reducing stigma around seeking help are vital steps. Policymakers should allocate more resources to mental health care, ensuring that those affected by psychosis and other mental health conditions receive the support they need.”
Another medical doctor doing a residency in neurology in Akure, Ondo State, Dr Michael Agip, said smoking weed frequently and starting at a young age may be risk factors for developing psychosis.
He said, “Research has shown that smoking weed can trigger a psychotic illness in a kid who might already be at risk for a disorder like schizophrenia.
“Smoking weed can both trigger and worsen psychotic symptoms. Studies have shown that adolescent marijuana use is not only a risk factor for the later development of primary psychotic disorders but is also a risk factor for an earlier onset of those disorders.”
According to the National Library of Medicine (National Centre for Biotechnology Information) in an article as far back as June 2008 noted that regular cannabis use and psychotic disorders (such as schizophrenia) are associated in the general population and heavy cannabis users are over-represented among new cases of schizophrenia.
These findings, and rising rates of cannabis use among young people in many developed countries, have prompted debates about whether cannabis use may be a contributory cause of psychosis, that is, it may precipitate schizophrenia in vulnerable individuals.
This hypothesis assumes that cannabis use is one factor among many others (including genetic predisposition and other unknown causes) that together cause schizophrenia.
There are also other possible explanations of the association. Common factors may increase the risk of cannabis use and psychosis, without the two being directly related.
Cannabis could also be used to self-medicate the symptoms of schizophrenia.
The consistent finding of an association between cannabis use and psychosis makes chance an unlikely explanation of the association, and there are also now several prospective studies showing that cannabis use often precedes psychosis.
The more difficult task has been excluding the hypothesis that the relationship is due to other factors, such as other drug use or a genetic predisposition to develop schizophrenia and use cannabis.
According to the research, the strongest evidence that cannabis use is a contributory cause of schizophrenia comes from longitudinal studies of large representative samples of the population who have been followed over time to see if cannabis users are at higher risk of developing schizophrenia.
French researchers also studied the relationship between cannabis use and psychotic symptoms using an “experience sampling method”.
These investigators asked 79 college students to report their drug use and psychotic symptoms at randomly selected time points, several times each day over seven consecutive days.
The students gave their ratings after being prompted to do so by a signal sent to a portable electronic device. High cannabis users (n=41) and students identified as vulnerable to psychosis (n=16) were over-represented.
In periods when cannabis was used, users reported more unusual perceptions and vulnerable individuals who used cannabis were more likely to report strange impressions and unusual perceptions than individuals who lacked this vulnerability.
There was no relationship between reporting unusual experiences and using cannabis, as would be expected if self-medication were involved.
Moore et al 23 reported a meta-analysis of six major longitudinal studies of the relationship between cannabis use and psychosis.
They found an increased risk (odds ratio, OR =1.4; 95 per cent confidence interval, CI: 1.20, 1.65) of psychotic disorder if someone ever used cannabis.
There was also a dose-response relationship between self-reported frequency of cannabis use and the risk of subsequently developing psychotic symptoms or a psychotic disorder (OR=2.09; 95 per cent CI: 1.54, 2.84).
They argued that reverse causation had been better controlled in the majority of these studies (by either excluding cases reporting psychotic symptoms at baseline or by statistically adjusting for pre-existing psychotic symptoms). In all studies the association between cannabis use and psychosis was attenuated after statistical adjustment for potential confounders.
Essien, explaining the findings of the research, noted that, given this evidence, excessive cannabis use can lead to hallucinations and subsequently schizophrenia.
The expert also added that given residual uncertainties about the evidence for a causal relation between cannabis and psychosis, the possible costs and benefits of different policy actions need to be considered.
Essien added that there was reasonable evidence that individuals with psychoses who are regular cannabis users have more positive symptoms, more frequent relapses, and require more hospitalisation.
“It is accordingly wise to encourage young people with psychotic symptoms who use cannabis to stop or, at the very least, to encourage them to reduce their frequency of use.
“The major challenges lie in finding ways to persuade individuals with schizophrenia to stop doing something they enjoy and to help those who want to stop using cannabis but find it difficult to do so.
“Recent evaluations of psychological interventions for cannabis dependence in individuals without psychoses report modest rates of abstinence at the end of treatment (20 to 40 per cent) and substantial rates of relapse thereafter.
“Many individuals with schizophrenia have characteristics that predict a poor outcome – they lack social support, they may be cognitively impaired, they are often unemployed, and they do not comply with treatment,” he added. (Punch)
