Homegrown cannabis raises risk of psychosis

CANNABIS users are exposing themselves to “higher risks of psychosis” by smoking super-strong homegrown herbal cannabis.

Research shows that herbal cannabis grown in factories here imposes a double whammy on users through a combination of high potency and the lack of protective chemicals typically found in cannabis resin.

Resin dominated the Irish cannabis market for decades, but there has been a shift to the herbal variety over the past five years. This switch has been particularly dramatic in the past three years, as the number of cannabis factories has soared.

A report conducted by the Forensic Science Laboratory (FSL), on behalf of the National Advisory Committee on Drugs (NACD), found that herbal cannabis seized here tended to be around three times the strength of resin.

Tests on samples of cannabis seized between September and November 2010 showed:

* The potency (THC content) of herbal cannabis ranged from 4% to 16%, while the strength of resin ranged from less than 1% to 5%.

* The potency in herbal cannabis seizures was far higher in the two homegrown factories (11% and 16%) compared to imported herbal cannabis (ranging between 4% and 9%). The factories in question were uncovered in Bandon, Co Cork, in September 2010.

In addition, the research found that the presence of another chemical, CBD, tended to be either low or very low in herbal cannabis, but in medium quantities in resin. CBD content was lowest in herbal cannabis grown here in factories.

The report’s author, Colette Arnold of the Forensic Science Laboratory said: “A recent study has shown that there is a higher risk of psychosis in those who smoke high-potency cannabis pro- ducts. Whilst it is the high THC and frequency of use of these products that may cause psychotic episodes, it is also thought to be attributed to the amount of CBD or lack thereof, in these products, as CBD is thought to decrease the effects of THC when ingested together.”

Cannabis seizures have jumped from 50 in 2006 to about 230 in 2009. In total about 20,000 plants have been seized.

The report said that while resin and herb were seized in equal numbers up to 2009, three times as many herb seizures were made in 2010, reflecting a trend across Europe.

It said the strength of homegrown cannabis was very similar to tests done in Britain. It said the potency of imported herbal cannabis was consistent, apart from the seizure in Tallaght (13%), which may have actually been cultivated here.

NACD chairman Dr Des Corrigan said: “Many of the plants being grown here are genetically selected to ensure they produce high levels of THC but they also lack a substance called CBD, which seems to protect the brain from the effects of THC, which can include psychosis.”


Potent reminder

DRUG treatment centres are seriously concerned at the number of young people using more potent forms of cannabis.

The Matt Talbot Adolescent Services in Cork has seen 280 adolescents so far this year, all of whom have used cannabis.

Director Geraldine Ring said the potency of cannabis now was causing “a lot of concern”.

She said: “Young people themselves agree that cannabis is much stronger in the last few years, but they love it.”

Ms Ring said they refer to this cannabis as “good stuff”, especially skunk (herbal cannabis), “squidgy black” (a form of cannabis resin) and “Marley” (a form of herbal cannabis).

“The strength of today’s marijuana is as much as 10 times greater than the marijuana used in the early 1970s,” said Ms Ring. “This more potent marijuana increases physical and mental effects and the possibility of health problems for the user.

“Young people with vulnerabilities to mental health [problems] need to avoid this drug.”

She said one young person told her it was “the only thing that calms the voices”, while others reported having “acute panic anxiety reaction” afterwards.

Dr Fiona Weldon, clinical director of the Rutland Centre in Dublin, said they were “very concerned” at the strength of cannabis.

“The one we are most aware of is skunk, which I think is the homegrown version. This has three times higher concentration of THC than cannabis resin,” she said.

Dr Weldon said users were not aware of the potency of the drug and that there was stronger evidence now linking cannabis to mental health problems, including psychosis and schizophrenia.

Dr Weldon said she would have “huge concern” with adolescents using the drug: “Their brain is still developing, so there are huge problems potentially to do with things like memory, language and planning, higher-level functions.”

* Contact: Matt Talbot on 021 4896400 or mtas.ie; Rutland Centre on 01 4946358 or rutlandcentre.ie

Cormac O’Keeffe

More in this section

Puzzles logo

Puzzles hub

Visit our brain gym where you will find simple and cryptic crosswords, sudoku puzzles and much more. Updated at midnight every day. PS ... We would love to hear your feedback on the section right HERE.

Let Me Tell You

Let Me Tell You is a new bespoke podcast series from 

Logo IE

Hosts Daniel McConnell and Paul Hosford take a look back at some of the most dramatic moments in recent Irish political history from the unique perspective of one of the key players involved.

Bespoke political podcast series from

Logo IE