Perspectives on cannabis and cannabis policy based on the research of prominent Danish scientist, Dr. Carsten Hjorthoj:
How can cannabis be causal for schizophrenia if the incidence of schizophrenia stays the same while cannabis use rises? There has been no consistent tracking of both cannabis use and schizophrenia in the United States. However, a powerful new study by Dr. Hjorthoj and colleagues demonstrates that as cannabis use disorder increased from 1992 to 2016 in Denmark, the incidence of schizophrenia also increased markedly. He writes “our study challenges the often cited argument against causality that an expected increase in cases of schizophrenia attributable to cannabis use has not been observed.”
Development Over Time of the Population-Attributable Risk Fraction for Cannabis Use Disorder in Schizophrenia in Denmark – PubMed
The results from these longitudinal analyses show the proportion of cases of schizophrenia associated with cannabis use disorder has increased 3- to 4-fold during the past 2 decades, which is expected given previously described increases in the use and potency of cannabis. This finding has important …
Is THC potentially harmful even at low doses? Yes, according to Dr.Hjorthoj: “there has been an increase in public perception of cannabis as relatively harmless, as well as international movements to legalise cannabis for medicinal or recreational purposes….It is thus of utmost importance that the public and politicians are informed of the most up-to-date evidence on cannabis…there are at least transient psychiatric symptoms associated with even relatively low doses of THC.”
Cannabis is a substance that is shrouded in myth, paradox, and controversy. On the one hand, a host of literature indicates detrimental effects on areas such as mental health (eg, increased risk of schizophrenia and poorer prognosis among patients with psychiatric disorders who also use cannabis), risk of addiction, and psychosocial functioning.1-4 On the other hand, there has been an increase in public perception of cannabis as relatively harmless, as well as international movements to legalise cannabis for medicinal or recreational purposes.
Following a substance induced psychosis, which drug results in the highest conversion rate to either schizophrenia or bipolar disorder?
“The highest conversion rate was found for cannabis, with 47.4% (95% CI542.7–52.3) converting to either schizophrenia or bipolar disorder”.
See our blog post, New Study Out of Denmark has Implications for Marijuana Legalization. It contains a podcast interview about Dr. Hjorthoj’s latest research.