In a study of 40 cannabis-dependent patients vs 40 healthy controls, cannabis abuse was associated with significant psychiatric symptoms but did not significantly alter thyroid hormones or cardiovascular parameters, likely due to tolerance development.
Psychiatrists, endocrinologists, and anyone interested in how chronic cannabis use affects different body systems differently.
Significant psychiatric symptoms (P < 0.001) but non-significant thyroid/cardiovascular changes
What the researchers found
Cannabis-dependent patients showed highly significant differences (P < 0.001) in positive, negative, and general psychopathology scores on the PANSS compared to controls. Among patients, 47.5% had schizophrenia, 20% schizoaffective symptoms, 10% manic symptoms, and 22.5% both manic and psychotic symptoms. Thyroid hormones (TSH, T3, T4) and cardiovascular parameters did not differ significantly between groups.
Why it matters
The dissociation between significant psychiatric effects and non-significant thyroid/cardiovascular changes in chronic cannabis users suggests tolerance may develop to some physiological effects while psychiatric vulnerability persists or worsens.
The numbers in context
40 patients vs 40 controls; 47.5% schizophrenia; PANSS scores P < 0.001; thyroid and cardiovascular parameters non-significant
How the study worked
Prospective multicenter study comparing 40 cannabis-dependent patients with psychotic symptoms (selected by DSM-IV criteria and urine testing) to 40 healthy controls. Thyroid hormones measured by immunoassay, psychiatric symptoms by PANSS, and cardiovascular parameters assessed.
What this study cannot tell us
Small sample. Cross-sectional comparison cannot determine whether cannabis caused psychiatric symptoms. All patients already had psychotic symptoms at enrollment. No dose-response analysis.
How to read the evidence
Small multicenter study with validated psychiatric assessments, but cannot establish causation and patients were pre-selected for psychotic symptoms.
When this study was published
Published in 2021.
The bigger picture
The finding that the body adapts (develops tolerance) to cannabis's thyroid and cardiovascular effects while psychiatric effects remain prominent suggests different biological systems respond differently to chronic exposure.
Questions still open
- Would thyroid effects appear in non-tolerant users? Does tolerance to cardiovascular effects provide false reassurance while psychiatric risk persists? Are the psychiatric symptoms truly cannabis-caused or pre-existing?
Common questions
Does cannabis affect thyroid hormones?
What psychiatric symptoms were found?
Read the original research
Clinical Investigation on the Impact of Cannabis Abuse on Thyroid Hormones and Associated Psychiatric Manifestations in the Male Population.
Frontiers in psychiatry, 12, 730388
Citation
Muzaffar, Anum; Ullah, Sami; Subhan, Fazal; Nazar, Zahid; Hussain, Syed Mehdi; Khuda, Fazli; Khan, Abuzar; Khusro, Ameer; Sahibzada, Muhammad Umar Khayam; Albogami, Sarah; El-Shehawi, Ahmed M; Emran, Talha Bin; Javed, Binish; Ali, Javed. (2021). Clinical Investigation on the Impact of Cannabis Abuse on Thyroid Hormones and Associated Psychiatric Manifestations in the Male Population.. Frontiers in psychiatry, 12, 730388. https://doi.org/10.3389/fpsyt.2021.730388
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