Electrophysiological Study of the Functioning of Magnocellular Visual Pathway in Regular Cannabis Users

Study Overview
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Brief Summary
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This study will evaluate the impact of regular use of cannabis on the spatial sensitivity of magnocellular system (visual event-related potential, visual ERP). Secondary purposes of this study are to evaluate the impact of regular use of cannabis on the temporal sensitivity of magnocellular system (visual event-related potential), on the dynamics of cortical visual processing during face perception test (visual event-related potential) and on functioning of retinal photopic and scotopic systems (electroretinogram). The ancillary study is a genetic analysis of a group of candidate genes that aims to identify biomarkers for changes in visual processing. This will allow to distinguish among more homogeneous and specific groups in future studies on larger cannabis user population. This ancillary study concerns all participants subject to their informed consent (facultative study).

Official Title
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Electrophysiological Study of the Functioning of Magnocellular Visual Pathway in Regular Cannabis Users

Conditions
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Cannabis Use

Intervention / Treatment
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* Other: Electroretinography
* Other: Contrast sensitivity test during Electroencephalography
* Other: Visual simultaneity test during Electroencephalography
* Other: Face perception test during Electroencephalography
* Other: CAST (cannabis abuse screening test)
* Other: PANSS (Positive And Negative Symptoms Scale) test
* Other: Delayed Matching to Sample (DMS) test
* Other: Spatial Working Memory (SWM) test
* Other: Rapid Visual Information Processing (RVP) test
* Other: Test for attentional performance (TAP) / Divided Attention
* Other: Collection of saliva sample


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Affiliation to social security plan Normal visual acuity or adjusted to normal and normal dilated fundus examination Signature of informed consent Cannabis user group: More than 7 cannabis uses per week during the previous month Cannabis user group: Positive urinary analysis for presence of cannabis Healthy, non user control group: Absence of cannabis and tobacco use during last 12 months Healthy, non user control group: Negative urinary analysis for presence of cannabis Healthy, non user control group: Age and sex matching with cannabis user group Healthy, tobacco user control group: Tobacco use from at least 12 months Healthy, tobacco user control group: Low to very strong addiction to tobacco (Fagerström test) Healthy, tobacco user control group: Absence of cannabis use from more than 12 months Healthy, tobacco user control group: Negative urinary analysis for presence of cannabis Healthy, tobacco user control group:Age and sex matching with cannabis user group Schizophrenia patient control group: Schizophrenia according to DMS IV criteria (MINI test) Schizophrenia patient control group: Absence of cannabis use from more than one month (regardless of tobacco use) Schizophrenia patient control group: Negative urinary analysis for presence of cannabis Schizophrenia patient control group: Age and sex matching with cannabis user group Exclusion Criteria: Acute psychiatric pathology (axis I of DSM IV, measured by MINI) except anxiety disorder (except schizophrenia group) Deficiency of the subject making difficult or impossible his/her participation to the study or the comprehension of the information Dyslexia Addiction to alcohol according to AUDIT scale Abuse or addiction to other substances according to DSM IV criteria Acute retinal disorder Chronic glaucoma Ophthalmic pathology affecting visual acuity Current ocular infection Persons under guardianship, curatorship or judicial protection Pregnant or breast-feeding women Persons with life-and-death emergency Absence of social security plan Results of preliminary medical examinations incompatible with the study Simultaneous participation to another therapeutic interventional study

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 55 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Other
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Cannabis users<br> | Other: Electroretinography<br> <br> Other: Contrast sensitivity test during Electroencephalography<br>* Stimuli are black and white grids, having different range of spatial frequencies, presented with different contrasts on a grey background thanks to a computer monitor, in a dark room. Participants are requested to maintain central fixation. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Visual simultaneity test during Electroencephalography<br>* Two vertical bars are showed on a monitor, on the link and right of point of central fixation. Bars appear simultaneously or with a 10 to 200 ms asynchrony. Participants must determine whether stimuli are simultaneous or asynchronous and answer pressing the link button for simultaneity or right button for asynchrony. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Face perception test during Electroencephalography<br>* Faces filtered in different spatial frequence ranges are showed randomly on a monitor, in a dark room. Participants must maintain a central fixation thank to a fixation cross. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: CAST (cannabis abuse screening test)<br> <br> Other: Delayed Matching to Sample (DMS) test<br> <br> Other: Spatial Working Memory (SWM) test<br> <br> Other: Rapid Visual Information Processing (RVP) test<br> <br> Other: Test for attentional performance (TAP) / Divided Attention<br> <br> Other: Collection of saliva sample<br>* In case of specific consent of participant to ancillary study, for ancillary study<br>|
| Other: Healthy volunteers, not cannabis/tobacco users<br> | Other: Electroretinography<br> <br> Other: Contrast sensitivity test during Electroencephalography<br>* Stimuli are black and white grids, having different range of spatial frequencies, presented with different contrasts on a grey background thanks to a computer monitor, in a dark room. Participants are requested to maintain central fixation. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Visual simultaneity test during Electroencephalography<br>* Two vertical bars are showed on a monitor, on the link and right of point of central fixation. Bars appear simultaneously or with a 10 to 200 ms asynchrony. Participants must determine whether stimuli are simultaneous or asynchronous and answer pressing the link button for simultaneity or right button for asynchrony. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Face perception test during Electroencephalography<br>* Faces filtered in different spatial frequence ranges are showed randomly on a monitor, in a dark room. Participants must maintain a central fixation thank to a fixation cross. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Delayed Matching to Sample (DMS) test<br> <br> Other: Spatial Working Memory (SWM) test<br> <br> Other: Rapid Visual Information Processing (RVP) test<br> <br> Other: Test for attentional performance (TAP) / Divided Attention<br> <br> Other: Collection of saliva sample<br>* In case of specific consent of participant to ancillary study, for ancillary study<br>|
| Other: Healthy volunteers, tobacco users<br> | Other: Electroretinography<br> <br> Other: Contrast sensitivity test during Electroencephalography<br>* Stimuli are black and white grids, having different range of spatial frequencies, presented with different contrasts on a grey background thanks to a computer monitor, in a dark room. Participants are requested to maintain central fixation. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Visual simultaneity test during Electroencephalography<br>* Two vertical bars are showed on a monitor, on the link and right of point of central fixation. Bars appear simultaneously or with a 10 to 200 ms asynchrony. Participants must determine whether stimuli are simultaneous or asynchronous and answer pressing the link button for simultaneity or right button for asynchrony. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Face perception test during Electroencephalography<br>* Faces filtered in different spatial frequence ranges are showed randomly on a monitor, in a dark room. Participants must maintain a central fixation thank to a fixation cross. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Delayed Matching to Sample (DMS) test<br> <br> Other: Spatial Working Memory (SWM) test<br> <br> Other: Rapid Visual Information Processing (RVP) test<br> <br> Other: Test for attentional performance (TAP) / Divided Attention<br> <br> Other: Collection of saliva sample<br>* In case of specific consent of participant to ancillary study, for ancillary study<br>|
| Other: Schizophrenia patients<br> | Other: Electroretinography<br> <br> Other: Contrast sensitivity test during Electroencephalography<br>* Stimuli are black and white grids, having different range of spatial frequencies, presented with different contrasts on a grey background thanks to a computer monitor, in a dark room. Participants are requested to maintain central fixation. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Visual simultaneity test during Electroencephalography<br>* Two vertical bars are showed on a monitor, on the link and right of point of central fixation. Bars appear simultaneously or with a 10 to 200 ms asynchrony. Participants must determine whether stimuli are simultaneous or asynchronous and answer pressing the link button for simultaneity or right button for asynchrony. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: Face perception test during Electroencephalography<br>* Faces filtered in different spatial frequence ranges are showed randomly on a monitor, in a dark room. Participants must maintain a central fixation thank to a fixation cross. During the test patients stay sit, head hold by chin strap. A pause can be asked by participant and done at every moment. This test lasts approximately 30 minutes.<br>Other: CAST (cannabis abuse screening test)<br> <br> Other: PANSS (Positive And Negative Symptoms Scale) test<br> <br> Other: Delayed Matching to Sample (DMS) test<br> <br> Other: Spatial Working Memory (SWM) test<br> <br> Other: Rapid Visual Information Processing (RVP) test<br> <br> Other: Test for attentional performance (TAP) / Divided Attention<br> <br> Other: Collection of saliva sample<br>* In case of specific consent of participant to ancillary study, for ancillary study<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Amplitude of P100 wave in contrast sensibility test |  | up to 1 month | 
| Culmination time of the P100 wave in contrast sensibility test |  | up to 1 month | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Amplitude of P100 wave in visual simultaneity test |  | up to 1 month | 
| Culmination time of P100 wave in visual simultaneity test |  | up to 1 month | 
| Amplitude of P100 wave in face perception test |  | up to 1 month | 
| Amplitude of N170 wave in face perception test |  | up to 1 month | 
| Culmination time of P100 wave in face perception test |  | up to 1 month | 
| Culmination time of N170 wave in face perception test |  | up to 1 month | 
| Amplitude of a wave in different ERG sequences |  | day 0 | 
| Amplitude of b wave in different ERG sequences |  | day 0 | 
| Culmination time of a wave in different ERG sequences |  | day 0 | 
| Culmination time of b wave in different ERG sequences |  | day 0 | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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cannabis, magnocellular pathway