Cannabis smokers are up to five times more likely to have suicidal thoughts than non-users, a new study reveals.
Researchers from the US National Institute on Drug Abuse (NIDA) studied data on the mental health and drug habits of more than 281,000 young adults.
They found that only 3 per cent of people who did not smoke cannabis had suicidal thoughts, but this rose to 14 per cent for those with a ‘cannabis use disorder’ — a near five-fold increase.
However, these stats were observed for people without depression, and the figures for those with depression were even more alarming.
Exactly half of the adults with both depression and a cannabis use disorder — defined as problematic cannabis use — were revealed to have suicidal thoughts.
Users of cannabis are more likely to think about, plan and attempt suicide even without a history of depression, a study has found — and woman are at more risk (stock image)
The team found incidences of suicidal thought or attempts increased with cannabis usage — with depressed women at 50 per cent more risk than their male peers.
Cannabis consumption is on the rise. In the US, for example, adult users have more than doubled in number from 22.6 million in 2008 to 45 million in 2019.
Over the same period, the number of adults with depression or having reported incidences of suicidal thoughts, planning or attempts has also increased.
CANNABIS: THE FACTS
Cannabis is an illegal Class B drug in the UK, meaning possession could result in a five year prison sentence and those who supply the drug face up to 14 years in jail.
However, the drug is widely used for recreational purposes and can make users feel relaxed and happy.
But smoking it can also lead to feelings of panic, anxiety or paranoia.
Scientific studies have shown the drug can alleviate depression, anxiety and stress, but heavy use may worsen depression in the long term by reducing the brain’s ability to let go of bad memories.
It can also contribute to mental health problems among people who already have them, or increase users’ risk of psychosis or schizophrenia.
Marijuana can be prescribed for medical uses in more than half of US states, where it is used to combat anxiety, aggression and sleeping problems.
Researchers are also looking into whether cannabis could also be used to help people with conditions including autism, eczema and psoriasis.
However, the exact nature of the relationship between cannabis use and suicidal thoughts remains unclear.
‘While we cannot establish that cannabis use caused the increased suicidality we observed in this study, these associations warrant further research,’ said paper author and psychiatrist Nora Volkow of NIDA.
This is especially important to do, she added, ‘given the great burden of suicide on young adults.’
‘As we better understand the relationship between cannabis use, depression and suicidality, clinicians will be able to provide better guidance and care to patients.’
In their study, Dr Volkow and colleagues analysed data on 281,650 young adults aged from 18–35 — the period during which most mood disorders and substance abuse problems emerge.
This data had been collected by the US Substance Abuse and Mental Health Services Administration from 2008–2019 as part of their National Surveys on Drug Use and Health, and features information on cannabis use and behavioural health.
Alongside looking for associations between these factors, the team also explored whether such varied by gender — with the subjects including a nearly even mix of men and women.
The researchers divided the subjects into four groups based on their level of cannabis use in the past year — specifically none, non-daily use, daily use and those with signs of cannabis use disorder.
Daily users were defined as those who used cannabis for at least 300 days in the preceding year, while cannabis use disorder is identified based on continued use in the face of negative consequences such as cravings and social withdrawal.
The team also looked in the data for evidence of major depressive episodes and the reported prevalence of suicidal ideation, planning and attempts.
Analysis revealed that even those who used cannabis on a non-daily basis — that is, for fewer than 300 days per year — were more likely to consider, plan or attempt suicide than people who did not use cannabis at all.
Furthermore, these associations were found to remain regardless of whether people were experiencing depression. Specifically, among the subjects without depression who did not report smoking cannabis, only around 3 per cent had suicidal thoughts.
This figure rose, however, to around 7 per cent with non-daily cannabis use, about 9 per cent with daily use and 14 per cent among those with a cannabis use disorder.
In those with depression, meanwhile, 35 per cent of non-cannabis use had suicidal ideation, compared with 44 per cent for nondaily cannabis users, 53 per cent with daily users and 50 per cent among those with a cannabis use disorder.
Similar associations, the researchers were noted, were seen between the extent of cannabis use and incidences of suicide planning or attempts.
In addition, the team found that women who use cannabis to any extent were more likely to report suicidal thoughts, planning or attempts than men with the same levels of cannabis use.
For example, among those subjects who had not experienced major depressive episodes, suicidal thoughts were reported by 13.9 per cent of women with cannabis use disorder vs 3.5 percent without — compared to 9.9 vs. 3.0 per cent of men.
And among the individuals suffering from both cannabis use disorder and major depressive episodes, the incidence of suicidal planning was 52 per cent higher among women (at 23.7 per cent) than men (15.6 per cent).
Among those subjects who had not experienced major depressive episodes, suicidal thoughts were reported by 13.9 per cent of women with cannabis use disorder vs 3.5 percent without — compared to 9.9 vs. 3.0 per cent of men (stock image)
‘Suicide is a leading cause of death among young adults in the United States and the findings of this study offer important information that may help us reduce this risk,’ said paper author and epidemiologist Beth Han, also of NIDA.
‘Depression and cannabis use disorder are treatable conditions, and cannabis use can be modified,’ she added.
‘Through better understanding the associations of different risk factors for suicidality, we hope to offer new targets for prevention and intervention in individuals that we know may be at high-risk.’
‘These findings also underscore the importance of tailoring interventions in a way that take sex and gender into account.’
The full findings of the study were published in the journal JAMA Network Open.