Combined effects of marijuana and nicotine on memory performance and hippocampal volume.
Francesca Filbey, Tim McQueeny, Shrinath Kadamangudi, Collette Bice, Ariel Ketcherside
Behavioural Brain Research October 15, 2015 DOI: 10.1016/j.bbr.2015.07.029 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Observational cross-sectional group comparison Peer reviewed |
|---|---|
| Sample size | 90 |
| Population | Adults from two larger studies: marijuana-only users, nicotine-only users, combined marijuana and nicotine users, and non-using healthy controls |
| Measures | WMS-III logical memory, total bilateral hippocampal volumes |
| Topics | Cannabis |
| Keywords | Comorbid substance use Hippocampus Morphometry Nicotine |
| Key findings | Marijuana-only and combined marijuana-plus-nicotine users had smaller total hippocampal volumes than nicotine-only users and controls, while immediate and delayed story recall did not differ significantly between groups. Controls showed a trend for larger hippocampal volumes to be associated with better memory, but combined users showed the reverse pattern, which the authors suggest indicates abnormalities in brain-behavior relationships underlying memory with combined use. |
Abstract
Combined use of marijuana (MJ) and tobacco is highly prevalent in today's population. Individual use of either substance is linked to structural brain changes and altered cognitive function, especially with consistent reports of hippocampal volume deficits and poorer memory performance. However, the combined effects of MJ and tobacco on hippocampal structure and on learning and memory processes remain unknown. In this study, we examined both the individual and combined effects of MJ and tobacco on hippocampal volumes and memory performance in four groups of adults taken from two larger studies: MJ-only users (n=36), nicotine-only (Nic-only, n=19), combined marijuana and nicotine users (MJ+Nic, n=19) and non-using healthy controls (n=16). Total bilateral hippocampal volumes and memory performance (WMS-III logical memory) were compared across groups controlling for total brain size and recent alcohol use. Results found MJ and MJ+Nic groups had smaller total hippocampal volumes compared to Nic-only and controls. No significant difference between groups was found between immediate and delayed story recall. However, the controls showed a trend for larger hippocampal volumes being associated with better memory scores, while MJ+Nic users showed a unique inversion, whereby smaller hippocampal volume was associated with better memory. Overall, results suggest abnormalities in the brain-behavior relationships underlying memory processes with combined use of marijuana and nicotine use. Further research will need to address these complex interactions between MJ and nicotine.
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 |
Citations in the library
Cited by 5
- The neuropsychopharmacology of cannabis: A review of human imaging studies Pharmacology & Therapeutics October 20, 2018
- Cognitive Outcomes among Cannabis Users with and without a History of Polysubstance Use Journal of Cognitive Enhancement September 14, 2026
- Altered brain structural and functional connectivity in cannabis users Scientific Reports April 10, 2023
- Differential associations of combined versus isolated cannabis and nicotine on brain resting state networks Brain Structure and Function June 7, 2018
- Association of Cannabis With Cognitive Functioning in Adolescents and Young Adults: A Systematic Review and Meta-analysis JAMA Psychiatry June 1, 2018
Cites 8
- Sub-chronic impact of cannabinoids in street cannabis on cognition, psychotic-like symptoms and psychological well-being Psychological Medicine February 1, 2012
- Medial temporal structures and memory functions in adolescents with heavy cannabis use Journal of Psychiatric Research February 5, 2011
- Longitudinal study of cognition among adolescent marijuana users over three weeks of abstinence. Addictive Behaviors November 2010
- Structural MRI findings in long-term cannabis users: what do we know? Substance Use & Misuse September 2010
- Chronic use of cannabis and poor neural efficiency in verbal memory ability. Psychopharmacology May 2010
and 3 more in the library