Association between increased retinal background noise and co-occurrent regular cannabis and alcohol use.
Alice Lucas, Audrey Thirion, Raymund Schwan, Julien Krieg, Karine Angioi-Duprez, Vincent Laprevote, Thomas Schwitzer
Progress in neuro-psychopharmacology & biological psychiatry March 8, 2019 DOI: 10.1016/j.pnpbp.2018.10.002 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cross-sectional study Peer reviewed |
|---|---|
| Sample size | 71 |
| Population | 26 healthy controls and 45 regular cannabis consumers, the latter divided by alcohol consumption (4 or fewer versus more than 4 glasses per week) |
| Measures | Flash electroretinogram (ERG), 3.0 flicker-response sequence, harmonic -1 and harmonic +1 magnitudes |
| Topics | Cannabis |
| Keywords | Alcohol Electroretinogram Retinal background noise |
| Key findings | Among regular cannabis users, those drinking more than 4 glasses of alcohol per week showed significantly greater retinal low-frequency background noise (harmonic -1 magnitude 6.78 versus 5.69) and greater average noise across two harmonics (5.12 versus 4.36) than those drinking 4 or fewer glasses. No significant difference appeared for harmonic +1. The authors propose the increased noise may reflect cannabis neurotoxicity potentiated by alcohol. |
Abstract
Cannabis consumption is widespread across the world, and the co-occurrence of cannabis use and alcohol consumption is common. The study of background noise - resting-state neural activity, in the absence of stimulation - is an approach that could enable the neurotoxicity of these substances to be explored. Preliminary results have shown that delta-9-tetrahydrocannabinol (Δ9-THC) causes an increase in neural noise in the brain. Neurons in the brain and the retina share a neurotransmission system and have similar anatomical and functional properties. Retinal function, evaluated using an electroretinogram (ERG), may therefore reflect central neurochemistry. This study analyses retinal background noise in a population of regular co-occurrent cannabis and alcohol consumers. We recorded the flash ERGs of 26 healthy controls and 45 regular cannabis consumers, separated into two groups based on their alcohol consumption: less than or equal to 4 glasses per week (CU ≤ 4) or strictly >4 glasses per week (CU >4). In order to extract the background noise, the Fourier transform of the pseudo-periodic and sinusoidal signals of the 3.0 flicker-response sequence was calculated. This sequence represents the vertical transmission of the signal from cones to bipolar cells. The magnitude of the background noise is defined as the average of the magnitudes of the two neighbouring harmonics: harmonic -1 (low frequency noise) and harmonic +1 (high frequency noise). The magnitude of harmonic -1 was significantly increased between the groups CU > 4 (6.78 (±1.24)) and CU ≤ 4 (5.69 (±1.80)) among regular users of cannabis and alcohol. A significant increase in the average magnitude of the two harmonics was found between the groups CU > 4 (5.12 (±0.92)) and CU ≤ 4 (4.36 (±1.14)). No significant difference was observed with regard to the magnitude of the harmonic +1. The increase in background noise may reflect the neurotoxicity of cannabis, potentiated by alcohol consumption, on retinal neurons dynamic. This neural disruption of the response generated by retinal stimulation may be attributable to altered neurotransmitter release.
Comparable studies
Other cross-sectional and survey studies on cannabis, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Cannabis use before age 15 and subsequent executive functioning 104 chronic cannabis users (49 early-onset before age 15, 55 late-onset after age 15)... | 2011 | Observational cross-sectional study | n = 148 |
| Patterns of simultaneous polysubstance use in drug using university students Drug-using university students | 2006 | Cross-sectional survey | n = 149 |
| Persisting Reductions in Cannabis, Opioid, and Stimulant Misuse After Naturalistic Psychedelic Use: An Online Survey Online survey respondents | 2020 | Cross-sectional survey | |
| User perceptions of the benefits and harms of hallucinogenic drug use: A web-based questionnaire study Users of hallucinogenic drugs who completed a web-based questionnaire | 2010 | Cross-sectional survey | n = 600 |
| Illicit Use of LSD or Psilocybin, but not MDMA or Nonpsychedelic Drugs, is Associated with Mystical Experiences in a Dose-Dependent Manner Adults recruited from the MAPS website and newsletter, most reporting use of various... | 2012 | Cross-sectional survey | n = 337 |