Cannabis DependenceNCT01793961
Effects of Chronic Intake of Cannabis on Contrast Sensitivity
A study testing electroretinogram and contrast sensitivity tests in people with Cannabis Dependence, run by University Hospital, Strasbourg, France at 1 site in France.
Trial summary
Rates of driving under the influence of cannabis have risen in recent years. Cannabis is involved in 1/3 of motor vehicle collisions. The chronic use of cannabis is known to affect dopaminergic regulation and may thus impair contrast sensitivity. Read more about this study
- Who is it for?
- Ages 18 to 50 yearsHealthy volunteers can take part
- Conditions the study is for
- Cannabis Dependence
- What is being tested?
- electroretinogram and contrast sensitivity tests
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 95 participants
- Where
- 1 siteFrance
- Study dates
- 22 Mar 2013to 10 Sep 2018
- Phase
- Interventional
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 50 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- "Cannabis" Arm
- patient addicted to cannabis
- Positive CAST test result
- Urine tested positive for cannabis metabolites
- "Tobacco" Arm
- positive Fagerström test result
Show all 11Show fewer
- No cannabis intake in the last year before inclusion
- No previous history of cannabis use
- "Healthy Volunteers"
- No tobacco or cannabis intake in the last year before inclusion
- No history of addictive disorders
Who cannot join
- addiction to other substances than cannabis or tobacco
- benzodiazepine treatment
- patient with history of benzodiazepine treatment
- patient with history of general anesthesia in the last 3 months before inclusion
- patient with history of head trauma
- Pregnant woman
- breast feeding woman
- Adults under supervision or guardianship
Trial locations and contacts
1 site in 1 country.
About this study
Rates of driving under the influence of cannabis have risen in recent years. Cannabis is involved in 1/3 of motor vehicle collisions. The chronic use of cannabis is known to affect dopaminergic regulation and may thus impair contrast sensitivity. In turn, contrast sensitivity disorders could originate difficulties to anticipate and avoid collision with objects, especially when objects are in movement. The investigators goal is to examine the effects of a chronic intake of cannabis on contrast sensitivity. The observed values will be compared to standard references. In addition, since smoking cannabis is always associated with tobacco, the investigators will control the effects of tobacco on contrast sensitivity.
In this study, the investigators will include 36 cannabis addicts, 36 tobacco addicts and 36 no smokers. The investigators will present gratings with different spatial frequencies and the investigators will determine contrast thresholds for static and dynamic (moving) gratings. The investigators predict that cannabis addicts will present abnormal contrast sensitivity especially in case of dynamic presentation of gradings.
- Conditions
- Cannabis Dependence
- Being tested
- electroretinogram, contrast sensitivity tests
- Medical subject headings
- Marijuana Abuse
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
electroretinogramOther
contrast sensitivity testsOther
| Study group | Role | What they receive |
|---|---|---|
| "Cannabis" Arm | Other | patient addicted to cannabis Receives: Other: electroretinogram; Other: contrast sensitivity tests |
| "Tobacco" Arm | Other | patient addicted to tobacco Receives: Other: electroretinogram; Other: contrast sensitivity tests |
| "Healthy volunteers" | Other | no smokers Receives: Other: electroretinogram; Other: contrast sensitivity tests |
What is being measured
The primary outcome is the main question the study is designed to answer.
The contrast detection treshold
Comparison of the contrast detection threshold of the 3 groups
Measured: up to 9 days after inclusion
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted18 Feb 2013 (estimated)
- Study start22 Mar 2013
- Primary completion30 Nov 2015
- Study completion10 Sep 2018
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Cannabis DependenceStudies of the same condition, open and under way.
- More trials run by University Hospital, Strasbourg, FranceThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 95 participants (actual)
Sponsor and investigators
- Lead sponsor
- University Hospital, Strasbourg, France
- Sponsor type
- University, hospital or other
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01793961
- Sponsor's protocol ID
- 5331
- Other IDs
- 2012-A00991-42
- Status last verified
- Jul 2019
- First submitted
- 12 Feb 2013
- Last updated
- 8 Jun 2026
- Results posted
- No
Study at a glance
From the registry record, last updated by the sponsor on 8 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Effects of Chronic Intake of Cannabis on Contrast Sensitivity
- ClinicalTrials.gov ID
- NCT01793961
- Acronym / sponsor ID
- 5331
- Conditions
- Cannabis Dependence
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 95 participants (actual)
- Lead sponsor
- University Hospital, Strasbourg, FranceUniversity, hospital or other
- Study start
- 22 Mar 2013 (actual)
- Primary completion
- 30 Nov 2015 (actual)
- Study completion
- 10 Sep 2018 (actual)
- First posted
- 18 Feb 2013 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
Rates of driving under the influence of cannabis have risen in recent years. Cannabis is involved in 1/3 of motor vehicle collisions. The chronic use of cannabis is known to affect dopaminergic regulation and may thus impair contrast sensitivity. In turn, contrast sensitivity disorders could originate difficulties to anticipate and avoid collision with objects, especially when objects are in movement. The investigators goal is to examine the effects of a chronic intake of cannabis on contrast sensitivity. The observed values will be compared to standard references. In addition, since smoking cannabis is always associated with tobacco, the investigators will control the effects of tobacco on contrast sensitivity.
In this study, the investigators will include 36 cannabis addicts, 36 tobacco addicts and 36 no smokers. The investigators will present gratings with different spatial frequencies and the investigators will determine contrast thresholds for static and dynamic (moving) gratings. The investigators predict that cannabis addicts will present abnormal contrast sensitivity especially in case of dynamic presentation of gradings.
Study design
- Primary purpose
- Other
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| "Cannabis" Arm | Other | Other: electroretinogram, Other: contrast sensitivity testspatient addicted to cannabis |
| "Tobacco" Arm | Other | Other: electroretinogram, Other: contrast sensitivity testspatient addicted to tobacco |
| "Healthy volunteers" | Other | Other: electroretinogram, Other: contrast sensitivity testsno smokers |
Who may qualify
- Ages
- 18 to 50 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (11 listed)
- "Cannabis" Arm
- patient addicted to cannabis
- Positive CAST test result
- Urine tested positive for cannabis metabolites
- "Tobacco" Arm
Key exclusion criteria (8 listed)
- addiction to other substances than cannabis or tobacco
- benzodiazepine treatment
- patient with history of benzodiazepine treatment
- patient with history of general anesthesia in the last 3 months before inclusion
- patient with history of head trauma
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| electroretinogram | Other | "Cannabis" Arm, "Healthy volunteers", "Tobacco" Arm |
| contrast sensitivity tests | Other | "Cannabis" Arm, "Healthy volunteers", "Tobacco" Arm |
Primary outcome
The contrast detection treshold
Time frame: up to 9 days after inclusion
Comparison of the contrast detection threshold of the 3 groups
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Jun 2026.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
The record lists no contact. Use the official record to reach the sponsor.
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing electroretinogram and contrast sensitivity tests in people with Cannabis Dependence, run by University Hospital, Strasbourg, France at 1 site in France.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 11 inclusion and 8 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 8 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in France. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
The contrast detection treshold (time frame: up to 9 days after inclusion). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 8 Jun 2026.