Cannabis and health from the NZ Cohorts

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Cannabis and health from the NZ cohorts

In a Radio NZ interview, Professor Richie Poulton reported on cannabis use in New Zealand.1 Although illegal, 80% of New Zealanders born in the 1970s reported using cannabis at least once.2

There was a risk of psychosis in a small proportion of those using cannabis under the age of 18 but not in older persons.

4 – 10% of past users were at risk of cannabis dependence syndrome that impaired psychological, social and educational functioning. Most users had no discernible impacts on health.

There was a dose-response relation with increasing and persistent use of cannabis and loss of cognitive capacity, respiratory function, periodontal disease, compromised educational and employment performance, criminal convictions, relationship difficulties, and driving impairment.

95% of those arrested did not stop using cannabis. Māori rates of arrest and conviction were three times higher than in non-Māori, even when other factors were accounted for.


  1. How does cannabis use affect New Zealanders' health? Radio NZ (2020) View here
  2. Patterns of recreational cannabis use in Aotearoa-New Zealand and their consequences: evidence to inform voters in the 2020 referendum. Journal of the Royal Society of New Zealand (2020) View here

Gems are chosen by the Goodfellow director Dr. Bruce Arroll to be either practice changing or practice maintaining. The information is educational and not clinical advice.

As published in NZ Doctor 12/08/2020