May 2026
Cannabis
What May 2026's 15 new studies found, synthesized from the papers below. All Cannabis research →
The synthesis
Synthesized from 15 studies in the library · AI-generated, grounded in the abstracts below
Found by searching the library for Cannabis, marijuana, THC, tetrahydrocannabinol, then ranked by relevance.
Research on cannabis in May 2026 consistently found that THC exposure impairs memory and alters brain connectivity, with effects varying by age, sex, and prior exposure. Acute THC also impaired driving, especially when combined with alcohol, and chronic use led to tolerance. However, findings on executive function were mixed, and most studies were preclinical or cross-sectional, limiting generalizability to humans.
Evidence by study
Direction is which way each study's own result points, not our rating of the study.
What the directions mean
- Supports:
- the study found the intervention worked, or its hypothesis held.
- Opposes:
- it found the opposite, no benefit or a harm.
- No effect:
- no significant difference either way.
- Mixed:
- effects in both directions within the same study.
- Unclear:
- the abstract does not report a direction.
| Study | Design | Sample size | Direction | Finding |
|---|---|---|---|---|
| Neuropsychological effects of cannabis use by continent and age: a systematic review 2026 | systematic review | 22 | Mixed | Memory impairments were consistent, but executive function deficits were heterogeneous and varied by age, exposure, study design, and cognitive task. |
| Retail Availability of Intoxicating Cannabis and Mushroom Products Across Eleven U.S. Cities: Sales Persist Despite Prohibitions. 2026 | cross-sectional survey | 1023 | Unclear | 51.4% of smoke shops sold intoxicating cannabis products, including 39.6% in states where illegal, and 59.7% sold hallucinogenic mushrooms regardless of legal status. |
| Cannabis, identity and the male teenage friendship group 2026 | qualitative study | Unclear | Cannabis use among teenage males was primarily social, facilitating identity exploration, and users viewed it as a temporary phase before adult responsibilities. | |
| The use of drug checking legislation to facilitate illicit drug consumption research: psychedelic microdosing as a case example 2026 | case study | Unclear | Drug checking legislation enabled research on microdosing and facilitated harm reduction information provision. | |
| Amanita muscaria in the evolving novel psychoactive substances landscape - toxicological risks and clinical implications: a narrative review 2026 | narrative review | Unclear | Amanita muscaria is increasingly used recreationally and for self-therapy, with adverse outcomes ranging from mild neurological symptoms to severe intoxication requiring hospitalization. | |
| Clinical and Pharmacological, Forensic and Pharmaceutical Profile of Hallucinogenic Sage Salvia Divinorum: Regulatory Restrictions, Internet Accessibility to Consumers, Risks to Public Health in Italy 2026 | review | Unclear | Effective counteraction to Salvia divinorum requires an integrated approach combining legislative control, monitoring, prevention, and health system preparedness. | |
| Prior cannabis vapor exposure impairs pattern separation in rodents of multiple ages but is rescued by citicoline administration. 2026 | randomized controlled trial | Supports | Vaporized THC or cannabis extract impaired spatial pattern separation in rats at all ages during early abstinence, and citicoline rescued these deficits. | |
| Effects of THC, CBD, and Their Combination on EEG Dynamics in Rats. 2026 | experimental study | Supports | Acute THC and THC+CBD increased low-frequency EEG power and altered functional connectivity in CB1 receptor-rich regions, with CBD alone having fewer effects. | |
| Prevalence and Reasons for Microdosing Cannabis, Psilocybin, LSD, and MDMA Among U.S. Adults 2026 | cross-sectional survey | 1523 | Unclear | Cannabis was the most commonly microdosed substance (9.4% lifetime prevalence), primarily for medical purposes, and microdosing was more common among those with poorer mental health and in less restrictive jurisdictions. |
| Effects of acute THC challenge on behavior and neuroinflammation in HIV-1 Tg26 mice vary based on HIV status, chronic THC history, and sex. 2026 | randomized controlled trial | 63 | Mixed | Chronic THC reduced sensitivity to acute THC's hypothermic, antinociceptive, and anxiolytic effects, especially in females, and this insensitivity development may depend on HIV genotype. |
| 0408 Insomnia Severity Differences by Psilocybin, LSD, and DMT Use Status Among Young Adult Daily Cannabis Consumers in the Herbal Heart Study 2026 | cross-sectional study | 100 | Mixed | LSD and DMT, but not psilocybin, were associated with moderate-to-severe clinical insomnia among young adult daily cannabis consumers. |
| Δ9-Tetrahydrocannabinol Alters Limbic and Frontal Functional Brain Connectomes Among Young Adult Cannabis Users. 2026 | within-subject, double-blind, randomized study | 33 | Supports | THC reduced within-network intrinsic connectivity in corticostriatal circuits and other networks, and reduced connectivity between anterior cingulate/dorsal insula and ventral insula/lingual gyrus networks. |
| Impact of Cannabis Edibles Combined With Alcohol on Driving, Field Sobriety Performance, and Subjective Effects: A Within-Participant Crossover Trial. 2026 | within-participant, double-blind, double-dummy crossover study | 25 | Supports | Cannabis edibles combined with alcohol augmented driving impairment, and the legal alcohol intoxication limit of 0.08% may be too liberal if a driver has co-used cannabis and alcohol. |
| Effects of sex and pre-exposure on Δ9-tetrahydrocannabinol (THC) vapor self-administration in rats. 2026 | preclinical experimental study | 96 | Supports | Rats self-administered THC vapor in a sustained manner, titrated intake based on concentration, showed sex differences in reinforcement, and THC pre-exposure increased subsequent self-administration. |
| Repeated Tetrahydrocannabinol Injections Induce Tolerance but Do Not Disrupt Ongoing Behaviour Upon Withdrawal in Male and Female Rats With Inflammatory Pain. 2026 | observational study with experimental manipulation | No effect | Persistent inflammatory pain did not alter the effects of repeated THC injections in male or female rats, and there was no evidence of spontaneous withdrawal. |
Memory impairments were consistent, but executive function deficits were heterogeneous and varied by age, exposure, study design, and cognitive task.
systematic review Sample size: 22
51.4% of smoke shops sold intoxicating cannabis products, including 39.6% in states where illegal, and 59.7% sold hallucinogenic mushrooms regardless of legal status.
cross-sectional survey Sample size: 1023
Cannabis use among teenage males was primarily social, facilitating identity exploration, and users viewed it as a temporary phase before adult responsibilities.
qualitative study
Drug checking legislation enabled research on microdosing and facilitated harm reduction information provision.
case study
Amanita muscaria is increasingly used recreationally and for self-therapy, with adverse outcomes ranging from mild neurological symptoms to severe intoxication requiring hospitalization.
narrative review
Effective counteraction to Salvia divinorum requires an integrated approach combining legislative control, monitoring, prevention, and health system preparedness.
review
Vaporized THC or cannabis extract impaired spatial pattern separation in rats at all ages during early abstinence, and citicoline rescued these deficits.
randomized controlled trial
Acute THC and THC+CBD increased low-frequency EEG power and altered functional connectivity in CB1 receptor-rich regions, with CBD alone having fewer effects.
experimental study
Cannabis was the most commonly microdosed substance (9.4% lifetime prevalence), primarily for medical purposes, and microdosing was more common among those with poorer mental health and in less restrictive jurisdictions.
cross-sectional survey Sample size: 1523
Chronic THC reduced sensitivity to acute THC's hypothermic, antinociceptive, and anxiolytic effects, especially in females, and this insensitivity development may depend on HIV genotype.
randomized controlled trial Sample size: 63
LSD and DMT, but not psilocybin, were associated with moderate-to-severe clinical insomnia among young adult daily cannabis consumers.
cross-sectional study Sample size: 100
THC reduced within-network intrinsic connectivity in corticostriatal circuits and other networks, and reduced connectivity between anterior cingulate/dorsal insula and ventral insula/lingual gyrus networks.
within-subject, double-blind, randomized study Sample size: 33
Cannabis edibles combined with alcohol augmented driving impairment, and the legal alcohol intoxication limit of 0.08% may be too liberal if a driver has co-used cannabis and alcohol.
within-participant, double-blind, double-dummy crossover study Sample size: 25
Rats self-administered THC vapor in a sustained manner, titrated intake based on concentration, showed sex differences in reinforcement, and THC pre-exposure increased subsequent self-administration.
preclinical experimental study Sample size: 96
Persistent inflammatory pain did not alter the effects of repeated THC injections in male or female rats, and there was no evidence of spontaneous withdrawal.
observational study with experimental manipulation
Points of agreement
- THC exposure impairs memory and alters brain connectivity across species and ages.
- Chronic THC exposure leads to tolerance and reduced sensitivity to acute effects.
- Cannabis products are widely available despite legal restrictions.
- Cannabis use is associated with social and identity-related motivations, especially among adolescents.
Conflicts
- Executive function deficits were consistent in some studies but heterogeneous in others.
- Psychedelic use was associated with insomnia for LSD and DMT but not psilocybin.
- Chronic THC reduced sensitivity in some measures but not others, and effects varied by sex and HIV status.
Gaps
- Most studies are preclinical or cross-sectional; long-term human data are limited.
- Durability of cognitive impairments and recovery after cessation is not well characterized.
- Blinding and placebo controls are often lacking in observational studies.
- Dose-response relationships and interactions with other substances (e.g., alcohol) need more research.
- Underrepresented populations include older adults, clinical samples, and non-Western regions.