Continuous THC Infusion in Four Monkeys Produced Delayed Disruption After Withdrawal

A 1986 study in four rhesus monkeys found that food-maintained responding could remain largely stable during continuous THC infusion but fall after it stopped. Little overt disruption during exposure did not rule out a later withdrawal-associated change.

The timing was part of the finding

Response-rate reductions generally emerged after a delay and could persist beyond a week in the initial experiments. That is a description of this infusion model, not a standard timeline for human cannabis withdrawal.

Re-exposure supplied another comparison

In a later phase, resuming THC halted the withdrawal-associated rate decreases, and stopping it again was followed by another decrease. The authors used this pattern to support a dependence interpretation. It did not directly measure subjective distress or every component of a clinical use disorder.

The model had substantial boundaries

The sample was small and exposure was continuous and intravenous. The investigators also repeated initial observations with lower solvent concentrations. These details matter when considering formulation effects and the limits of translating an experimental regimen to ordinary cannabis use.

Interpreting the evidence

This experiment separates on-drug behavior from behavior after discontinuation. It does not establish that every tolerant user is dependent or that a stable response rate during exposure proves absence of later withdrawal. Species, dosing method and the actual task remain essential.

Related reading: interpreting cannabis tolerance claims.

Research reference

Beardsley PM; Balster RL; Harris LS (1986). Dependence on tetrahydrocannabinol in rhesus monkeys. The Journal of pharmacology and experimental therapeutics. PubMed research record.

This analysis draws on the supplied study abstract.