A review article published in the journal Epidemiology describes the mental health impact of cannabis use in Australian and American youth.
Study: Cannabis use and its impact on youth mental health in Australia and the United States: A scoping review. Image credit: hikrcn / Shutterstock
Record
Cannabis has a centuries-old history of use for medicinal, spiritual and recreational purposes. Its popularity is increasing among young people worldwide, reflecting a global prevalence of 2.8%.
The estimated prevalence of cannabis use among youth in the United States is 7.1%, making it the second most used substance after alcohol. In Australia, the prevalence of cannabis use is around 34% among young people aged 14 and over.
The use of cannabis is increasing worldwide due to the general perception of its harmless nature and lack of dependence. However, a large body of evidence points to the negative health impact of long-term and frequent cannabis use.
The psychoactive compound 9 delta-tetrahydrocannabinol (THC) present in cannabis is primarily responsible for adverse mental health outcomes among users. Cannabis also contains a number of beneficial bioactive compounds, including cannabichromine (CBC), which is known to have analgesic, neuroprotective and anti-inflammatory properties.
In this review, the authors have extensively analyzed the existing evidence on the impact of cannabis use on mental health among Australian and American youth.
The nature of cannabis legalization is similar in these countries. The recreational and medical use of cannabis is already legal in many states, while others are in the process of legalizing it. Because of these factors, these two countries present a unique context for studying the effects of cannabis use on mental health.
Study design
The authors searched various online databases to select relevant human studies on the impact of cannabis use on mental health among young populations in Australia and the US. They included peer-reviewed journal articles published in English, including systematic reviews, meta-analyses and cohort studies, longitudinal and cross-sectional studies.
A total of 24 studies were selected and analyzed in the review, which included three systematic reviews and meta-analyses, seven cohort studies, seven longitudinal studies and seven cross-sectional studies. Of these studies, three were conducted in Australia and 21 in the USA.
Important observations
The studies selected in the review highlighted the negative impact of cannabis use on various mental health issues, including depression, anxiety, suicide risk, psychosis, cannabis dependence and other mental disorders.
Depression and anxiety
The analysis revealed that cannabis use significantly increases the risk of depression among young people aged 12 to 32. The risk was comparatively higher among African-American women and those belonging to LGBTQI groups.
A trend of increasing cannabis use from adolescence to adulthood was observed in some studies. However, no definitive correlation was found between the age of cannabis use and the development of depression.
Regarding the risk of anxiety, studies have produced mixed results, with some showing a significantly higher risk of developing anxiety due to cannabis use and others showing the absence of any such association.
Risk of suicide
The analysis revealed that cannabis use may increase the risk of suicidal ideation, suicidal thoughts and suicide plans among adolescents. An association of past-year cannabis use disorder, daily cannabis use, and non-daily cannabis use was also observed with higher rates of suicidal ideation, suicide planning, and attempted suicide among youth.
The increase in suicide risks associated with cannabis use was more significant among youth with or without a cannabis use disorder. However, females showed greater sensitivity than males.
Psychosis
A direct association between cannabis use frequency and cannabis use disorder and psychosis risk was observed among youth, with females showing a higher prevalence than males.
Young people who used cannabis more often had a higher risk of developing psychotic symptoms, such as hallucinations and paranoia.
Cannabis use disorder and dependence
Intensity of cannabis use showed a direct association with cannabis use disorder, with recent users at higher risk than non-users. Higher susceptibility to alcohol and opioid use was observed among adolescents with cannabis use disorder.
Considering the different forms of cannabis, the evidence showed that the risk of a cannabis use disorder, abuse and dependence is highest for blunt use, followed by dual use of cigars and both blunt and non-blunt use of marijuana.
Importance of study
This review article highlights that cannabis use in youth is associated with risk for depression, psychosis, suicidality, cannabis use disorder, dependence, cognitive impairment and externalizing behaviour, particularly attention deficit hyperactivity disorder.
The risk of developing mental health problems is related to the frequency, duration, intensity and types of cannabis use. Factors that can significantly increase the risk of mental health problems include being female, minority, LGBTQI, African American, Aboriginal and Torres Strait Islander, and age of initiation of cannabis use.
Overall, the findings highlight the need to increase youth awareness of the negative impact of cannabis use on mental health.
