
Is Cannabis Use Increasing Schizophrenia?
Is cannabis’ effect on schizophrenia being downplayed?
COMMENTARY
The juxtaposition of 2 recent research reports should give us pause for concern. In September, the National Institute on Drug Abuse reported that
The National Institute of Mental Health (NIMH) website describes itself as “the lead federal agency for research on mental disorders.” Schizophrenia is generally considered to be the most disabling mental disorder and in 2013 was estimated to cost the US $155.7 billion annually.6 One would therefore expect NIMH to have accurate information on the incidence and prevalence of schizophrenia and some idea whether they are increasing, decreasing, or constant over time. However, when a health reporter asked NIMH for its reaction to the report on cannabis and
In fact, NIMH says that it does not know the prevalence of schizophrenia in the US other than within broad limits.8,9 For the last 4 years, the NIMH website has combined schizophrenia with other “related psychotic disorders” and claimed that together, their prevalence is “between 0.25% and 0.64%” of the population, which translates to between 772,000 and 2.0 million individuals. For every other mental disorder, except schizophrenia, NIMH provides a precise prevalence number.
Part of the problem is that NIMH has not undertaken a serious study of the incidence or prevalence of
In order to ascertain whether any disease is increasing or decreasing over time, one needs a reliable baseline number as well as repeated surveys. Since NIMH has never repeated the prevalence survey for the 40-year-old study or established another reliable baseline number, it has no way to tell whether schizophrenia is increasing or decreasing. In fact, since the 1990s, there are suggestions that it may be increasing. The number of seriously mentally ill individuals who are homeless or incarcerated has appeared to increase in recent years, and schizophrenia is a significant part of that population. Schizophrenia is a major, and apparently increasing, contributor to the cost of the Medicaid and Medicare programs. And the “mental disorders” diagnostic category has been 1 of the fastest-growing parts of the Supplemental Security Income and Social Security Disability Income programs.14
It is an embarrassment to American medicine that NIMH has so little to contribute on such an important question. At a minimum, NIMH should issue a request for proposals to try and confirm the Danish study in another country which has appropriate data so that we will have a definitive answer to this question.
Dr Torrey is the founder of the Treatment Advocacy Center and the author of American Psychosis: How the Federal Government Destroyed the Mental Illness Treatment System.
References
1. Marijuana use at historic high among college-aged adults in 2020. National Institute on Drug Abuse. September 8, 2021. Accessed December 22, 2021.
2. Hjorthøj C, Posselt CM, Nordentoft M.
3. Boydell J, Van Os J, Lambri M, et al.
4. Ajdacic-Gross V, Lauber C, Warnke I, et al.
5. Bray I, Waraich P, Jones W, et al.
6. Cloutier M, Aigbogun MS, Guren A, et al.
7. Hunt K. Schizophrenia linked to marijuana use disorder is on the rise, study finds. CNN Health. July 22, 2021. Accessed December 22, 2021.
8. Gordon JA. On the prevalence of schizophrenia-and transforming care through research. Psychiatric Times. March 14, 2018.
9. Gordon JA. Letter to Senator Bernard Sanders. February 6, 2019.
10. Regier DA, Narrow WE, Rae ES, et al.
11. Kessler RC, Birnbum H, Demler O, et al.
12. Torrey EF, Sinclair E. Hocus pocus: how the NIMH made 2 million people with schizophrenia disappear. Psychiatric Times. March 14, 2018.
13. Torrey EF, Simmons W. Where did the schizophrenics go? The Wall Street Journal. March 26, 2019. Accessed December 22, 2021.
14. Torrey EF. Severe psychiatric disorders appear to be increasing. Psychiatric Times. April 1, 2002.
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