Monitored Cannabis Abstinence Was Achievable for Many Schizophrenia Patients | Research

The takeaway

Using contingency management, 42% of cannabis-dependent schizophrenia patients achieved 28 days of verified abstinence, comparable to the 55% rate in non-psychiatric controls.

Psychiatrists, addiction specialists, and schizophrenia researchers.

42% of schizophrenia patients vs 55% of controls achieved 28-day cannabis abstinence (no significant difference).

What the researchers found

With contingency management incentives and twice-weekly urine monitoring, cannabis-dependent schizophrenia patients achieved abstinence rates statistically similar to controls (42.1% vs 55%, p=0.53). Both groups showed increased withdrawal symptoms during abstinence, confirming genuine cessation.

Why it matters

Cannabis use disorders are about 8 times more common in people with schizophrenia than in the general population. This study shows that structured abstinence programs can work for this population, and at rates not far from the general population.

The numbers in context

42.1% (8/19) of patients achieved 28-day abstinence vs 55% (11/20) of controls (p=0.53). Quantitative THC-COOH metabolite levels below 20 ng/mL confirmed abstinence.

How the study worked

19 cannabis-dependent schizophrenia patients and 20 non-psychiatric controls underwent 28 days of monitored abstinence with contingency management. Urine was tested twice weekly using qualitative and quantitative methods (GC-MS). Subjective withdrawal assessments were also used.

What this study cannot tell us

Small sample size (39 total). Contingency management provides financial incentives that may not reflect real-world motivation. 28 days may not indicate long-term abstinence capacity.

How to read the evidence

Preliminary - small pilot study without randomization or control condition for the intervention itself.

When this study was published

Published in 2018.

The bigger picture

The high rate of cannabis use disorders in schizophrenia has long concerned clinicians. Demonstrating that structured abstinence is feasible opens doors for studying how stopping cannabis affects psychiatric symptoms and cognitive function in this population.

Questions still open

What happens after the incentive structure is removed? Does achieving abstinence improve psychiatric symptoms? Would longer abstinence periods be achievable with continued support?

Common questions

Can people with schizophrenia quit cannabis?

This study found that with structured monitoring and incentives, 42% of cannabis-dependent schizophrenia patients achieved 28 days of verified abstinence - not significantly different from non-psychiatric controls.

What is contingency management for drug use?

Contingency management provides incentives (often financial) for meeting behavioral goals like abstinence, verified through urine testing. This study used it to help cannabis-dependent participants stay abstinent for 28 days.

Read the original research

A method to achieve extended cannabis abstinence in cannabis dependent patients with schizophrenia and non-psychiatric controls.

Schizophrenia research, 194, 47-54

View on PubMed ↗Publisher’s paper ↗

Citation

Rabin, Rachel A; Kozak, Karolina; Zakzanis, Konstantine K; Remington, Gary; Stefan, Cristiana; Budney, Alan J; George, Tony P. (2018). A method to achieve extended cannabis abstinence in cannabis dependent patients with schizophrenia and non-psychiatric controls.. Schizophrenia research, 194, 47-54. https://doi.org/10.1016/j.schres.2017.05.006