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May 2026

Cannabis

What May 2026's 9 new studies found, synthesized from the papers below. All Cannabis research →

The synthesis

Synthesized from 5 studies in the library · AI-generated, grounded in the abstracts below

Found by searching the library for Cannabis, marijuana, THC, cannabidiol, CBD, then ranked by relevance.

Research on cannabis published in May 2026 found that THC impairs memory, alters brain connectivity, and worsens driving performance, especially when combined with alcohol. Effects on executive function were mixed and varied by age and region. A key caveat is that many studies used small samples or animal models, limiting generalizability.

Confidence in the evidence

Moderate
  • Multiple studies (RCTs, systematic review, animal studies) consistently show memory impairment and altered brain connectivity with THC.
  • The systematic review included 22 studies, providing a broad evidence base, but findings on executive function were heterogeneous.
  • The driving study was a well-controlled crossover trial with 25 participants, but sample size is modest.
  • Animal studies (rats, mice) support human findings but limit direct applicability.
How we rate confidence

Confidence reflects the strength of the underlying evidence, not whether the result is favorable. It weighs the number and size of studies, their design (randomized trials count for more than observational or single-case work), how consistently they point the same way, and their risk of bias.

Tiers run from Insufficient to High. High is rare in this field: small, early, or open-label studies land lower even when their direction is encouraging.

Evidence by study

Direction is each study's finding relative to your question: Supports, Opposes, No effect, Mixed, or Unclear.

Neuropsychological effects of cannabis use by continent and age: a systematic review 2026
Opposes

Memory impairments were the most consistent finding across studies, while executive function results were heterogeneous.

systematic review · Sample size: 22

Effects of THC, CBD, and Their Combination on EEG Dynamics in Rats. 2026
Supports

THC and THC+CBD increased low-frequency EEG power and altered functional connectivity in brain regions rich in CB1 receptors.

animal study

Δ9-Tetrahydrocannabinol Alters Limbic and Frontal Functional Brain Connectomes Among Young Adult Cannabis Users. 2026
Opposes

Acute THC reduced within-network connectivity in corticostriatal and sensory networks, and reduced between-network connectivity in limbic and frontal regions.

RCT · Sample size: 33

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
Mixed

Chronic THC history led to minor behavioral changes and overall decreases in cytokines/chemokines, with effects varying by HIV status and sex.

animal study · Sample size: 63

Impact of Cannabis Edibles Combined With Alcohol on Driving, Field Sobriety Performance, and Subjective Effects: A Within-Participant Crossover Trial. 2026
Opposes

Cannabis edibles alone and with alcohol impaired driving performance and field sobriety tests, with additive effects when combined.

RCT · Sample size: 25

Points of agreement

  • THC consistently impairs memory and alters brain connectivity.
  • Cannabis impairs driving performance, especially when combined with alcohol.
  • Animal models show THC alters EEG dynamics and neuroinflammatory markers.

Conflicts

  • Executive function findings were heterogeneous across studies in the systematic review.
  • Chronic THC history produced only minor behavioral changes in mice, contrasting with acute effects in humans.

Gaps

  • Long-term durability of cognitive impairments is not addressed.
  • Effects in older adults or clinical populations are not studied.
  • Dose-response relationships and sex differences are underexplored in human studies.
  • Real-world driving performance after cannabis use is not assessed.
Browse these studies in the library