Rhesus monkeys develop physical dependence on THC with daily use | Research

The takeaway

Rhesus monkeys given THC twice daily developed clear physical dependence, showing a 20-fold increase in activity when withdrawal was triggered, while monkeys given THC only every 3 days did not.

Researchers studying cannabis dependence, daily cannabis users, and addiction medicine specialists.

20-fold activity increase during precipitated withdrawal

What the researchers found

Chronic THC (1 mg/kg every 12 hours) produced dependence: rimonabant-precipitated withdrawal caused up to 20-fold increase in home-cage activity. Intermittent THC (0.1 mg/kg every 3 days) did not produce dependence signs. Abrupt discontinuation of chronic THC caused immediate (within 24 hours) and progressive increases in activity. THC was somewhat more potent in reducing activity in the intermittent group, consistent with tolerance development in the chronic group.

Why it matters

Primate models are more translatable to humans than rodent models. This study establishes clear, measurable physical dependence in primates using a simple behavioral measure.

The numbers in context

Chronic: 1 mg/kg every 12 hours. Intermittent: 0.1 mg/kg every 3 days. Rimonabant doses: 0.1-3.2 mg/kg. Up to 20-fold activity increase during precipitated withdrawal. Spontaneous withdrawal began within 24 hours.

How the study worked

Two groups of rhesus monkeys: one receiving chronic THC (1 mg/kg every 12 hours) and one receiving intermittent THC (0.1 mg/kg every 3 days). Home-cage activity was measured continuously. Withdrawal was assessed via rimonabant challenge and abrupt discontinuation.

What this study cannot tell us

Animal study (primates). Activity is only one measure of withdrawal. Dose and frequency may not directly correspond to human use patterns.

How to read the evidence

Well-controlled primate study with objective behavioral measures, but animal model with limited sample size.

When this study was published

2019 preclinical study.

The bigger picture

The contrast between chronic and intermittent dosing directly parallels the human experience where daily heavy users report withdrawal but occasional users typically do not.

Questions still open

At what frequency of use does physical dependence begin to develop? Would a gradual taper prevent the withdrawal activity increase?

Common questions

Does daily cannabis use cause physical dependence?

In this primate study, monkeys receiving THC twice daily developed clear physical dependence with measurable withdrawal signs, while those receiving THC every 3 days did not.

What does THC withdrawal look like?

In these monkeys, withdrawal manifested as dramatic increases in home-cage activity (up to 20-fold), beginning within 24 hours of the last dose and increasing over time.

Read the original research

Tolerance and dependence to Δ9-tetrahydrocannabinol in rhesus monkeys: Activity assessments.

PloS one, 14(3), e0209947

View on PubMed ↗Publisher’s paper ↗

Citation

Wilkerson, Jenny L; Schulze, David R; McMahon, Lance R. (2019). Tolerance and dependence to Δ9-tetrahydrocannabinol in rhesus monkeys: Activity assessments.. PloS one, 14(3), e0209947. https://doi.org/10.1371/journal.pone.0209947