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The effects of cannabis on memory function in users with and without a psychotic disorder: findings from a combined meta-analysis

  • T. Schoeler (a1), J. Kambeitz (a1) (a2), I. Behlke (a1) (a3), R. Murray (a1) and S. Bhattacharyya (a1)...



Effect of cannabis use on memory function is a contentious issue, with effects being different in healthy individuals and patients with psychosis.


Employing a meta-analytic approach we investigated the effects of cannabis use on memory function in patients with psychosis and healthy individuals, and the effect of diagnosis, memory dimension and moderating factors. A total of 88 studies were identified through a systematic literature search, investigating healthy (n = 7697) and psychotic (n = 3261) individuals. Standardized mean differences between the cannabis user and non-user groups on memory tasks were estimated using random-effects models and the effect-size statistic Cohen's d. Effects of potential moderating factors were tested using mixed-effects models and subgroup analyses.


We found that cannabis use was associated with significantly (p ⩽ 0.05) impaired global (d = 0.27) and prospective memory (d = 0.61), verbal immediate (d = 0.40) and delayed (d = 0.36) recall as well as visual recognition (d = 0.41) in healthy individuals, but a better global memory (d = −0.11), visual immediate recall (d = −0.73) and recognition (d = −0.42) in patients. Lower depression scores and younger age appeared to attenuate the effects of cannabis on memory. Cannabis-using patients had lower levels of depression and were younger compared with non-using patients, whilst healthy cannabis-users had higher depression scores than age-matched non-users. Longer duration of abstinence from cannabis reduced the effects on memory in healthy and patient users.


These results suggest that cannabis use is associated with a significant domain-specific impairment in memory in healthy individuals but not in cannabis-using patients, suggesting that they may represent a less developmentally impaired subgroup of psychotic patients.


Corresponding author

* Address for correspondence: S. Bhattacharyya, M.B.B.S., M.D., Ph.D., Department of Psychosis Studies, Institute of Psychiatry, King's College London, De Crespigny Park, London SE5 8AF, UK. (Email:


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Bahorik, AL, Newhill, CE, Eack, SM (2013). Neurocognitive functioning of individuals with schizophrenia: using and not using drugs. Schizophrenia Bulletin 40, 856867.
Beller, EM, Glasziou, PP, Altman, DG, Hopewell, S, Bastian, H, Chalmers, I, Gøtzsche, PC, Lasserson, T, Tovey, D (2013). PRISMA for abstracts: reporting systematic reviews in journal and conference abstracts. PLoS Medicine 10, e1001419.
Benedict, RHB, Schretlen, D, Groninger, L, Brandt, J (1998). Hopkins Verbal Learning Test–revised: normative data and analysis of inter-form and test–retest reliability. Clinical Neuropsychologist 12, 4355.
Bhattacharyya, S, Atakan, Z, Martin-Santos, R, Crippa, JA, Kambeitz, J, Prata, D, Williams, S, Brammer, M, Collier, DA, McGuire, PK (2012). Preliminary report of biological basis of sensitivity to the effects of cannabis on psychosis: AKT1 and DAT1 genotype modulates the effects of δ-9-tetrahydrocannabinol on midbrain and striatal function. Molecular Psychiatry 17, 11521155.
Bhattacharyya, S, Fusar-Poli, P, Borgwardt, S, Martin-Santos, R, Nosarti, C, O'Carroll, C, Allen, P, Seal, ML, Fletcher, PC, Crippa, JA, Giampietro, V, Mechelli, A, Atakan, Z, McGuire, P (2009). Modulation of mediotemporal and ventrostriatal function in humans by Δ9-tetrahydrocannabinol: a neural basis for the effects of Cannabis sativa on learning and psychosis. Archives of General Psychiatry 66, 442451.
Bolla, KI, Brown, K, Eldreth, D, Tate, K, Cadet, JL (2002). Dose-related neurocognitive effects of marijuana use. Neurology 59, 13371343.
Borenstein, M, Hedges, LV, Higgins, JP, Rothstein, HR (2011). Introduction to Meta-Analysis. Wiley: Chichester.
Bowman, M, Pihl, RO (1973). Cannabis: psychological effects of chronic heavy use. Psychopharmacologia 29, 159170.
Bugra, H, Studerus, E, Rapp, C, Tamagni, C, Aston, J, Borgwardt, S, Riecher-Rössler, A (2013). Cannabis use and cognitive functions in at-risk mental state and first episode psychosis. Psychopharmacology (Berlin) 230, 299308.
Burt, DB, Zembar, MJ, Niederehe, G (1995). Depression and memory impairment: a meta-analysis of the association, its pattern, and specificity. Psychological Bulletin 117, 285305.
Carey, KB, Carey, MP, Simons, JS (2003). Correlates of substance use disorder among psychiatric outpatients: focus on cognition, social role functioning and psychiatric status. Journal of Nervous and Mental Disease 191, 300308.
Cunha, PJ, Rosa, PGP, Ayres, Ade M, Duran, FLS, Santos, LC, Scazufca, M, Menezes, PR, dos Santos, B, Murray, RM, Crippa, JAS, Busatto, GF, Schaufelberger, MS (2013). Cannabis use, cognition and brain structure in first-episode psychosis. Schizophrenia Research 147, 209215.
Curran, VH, Brignell, C, Fletcher, S, Middleton, P, Henry, J (2002). Cognitive and subjective dose–response effects of acute oral Δ9-tetrahydrocannabinol (THC) in infrequent cannabis users. Psychopharmacology (Berlin) 164, 6170.
D'Souza, DC, Abi-Saab, WM, Madonick, S, Forselius-Bielen, K, Doersch, A, Braley, G, Gueorguieva, R, Cooper, TB, Krystal, JH (2005). Δ−9-Tetrahydrocannabinol effects in schizophrenia: implications for cognition, psychosis, and addiction. Biological Psychiatry 57, 594608.
D'Souza, DC, Perry, E, MacDougall, L, Ammerman, Y, Cooper, T, Wu, YT, Braley, G, Gueorguieva, R, Krystal, JH (2004). The psychotomimetic effects of intravenous Δ−9-tetrahydrocannabinol in healthy individuals: implications for psychosis. Neuropsychopharmacology 29, 15581572.
Donoghue, K, Doody, GA (2012). Effect of illegal substance use on cognitive function in individuals with a psychotic disorder, a review and meta-analysis. Neuropsychology 26, 785801.
Donoghue, K, Mazzoncini, R, Hart, J, Zanelli, J, Morgan, C, Dazzan, P, Morgan, KD, Murray, RM, Jones, PB, Doody, GA (2012). The differential effect of illicit drug use on cognitive function in first-episode psychosis and healthy controls. Acta Psychiatrica Scandinavica 125, 400411.
Eichenbaum, H (1993). Memory, Amnesia, and the Hippocampal System. The MIT Press: Cambridge, MA.
Englund, A, Morrison, PD, Nottage, J, Hague, D, Kane, F, Bonaccorso, S, Stone, JM, Reichenberg, A, Brenneisen, R, Holt, D (2013). Cannabidiol inhibits THC-elicited paranoid symptoms and hippocampal-dependent memory impairment. Journal of Psychopharmacology 27, 1927.
Ferraro, L, Russo, M, O'Connor, J, Wiffen, BDR, Falcone, MA, Sideli, L, Gardner-Sood, P, Stilo, S, Trotta, A, Dazzan, P, Mondelli, V, Taylor, H, Friedman, B, Sallis, H, La Cascia, C, La Barbera, D, David, AS, Reichenberg, A, Murray, R, Di Forti, M (2013). Cannabis users have higher premorbid IQ than other patients with first onset psychosis. Schizophrenia Research 150, 129135.
Fletcher, PC, Honey, GD (2006). Schizophrenia, ketamine and cannabis: evidence of overlapping memory deficits. Trends in Cognitive Sciences 10, 167174.
Fried, PA, Watkinson, B, Gray, R (2005). Neurocognitive consequences of marihuana – a comparison with pre-drug performance. Neurotoxicology and Teratology 27, 231239.
Gonzalez, R, Carey, C, Grant, I (2002). Nonacute (residual) neuropsychological effects of cannabis use: a qualitative analysis and systematic review. Journal of Clinical Pharmacology 42 (11 Suppl.), 48S57S.
Grant, I, Gonzales, R, Carey, CL, Natarajan, L, Wolfson, T (2003). Non-acute (residual) neurocognitive effects of cannabis use: a meta-analytic study. Journal of the International Neuropsychological Society 9, 679689.
Gruber, SA, Sagar, KA, Dahlgren, MK, Racine, M, Lukas, SE (2012). Age of onset of marijuana use and executive function. Psychology of Addictive Behaviors 26, 496506.
Hardwick, S, King, LA (2008). Home Office Cannabis Potency Study 2008. United Kingdom: Home Office Scientific Development Branch: St Albans.
Herkenham, M, Lynn, AB, Little, MD, Johnson, MR, Melvin, LS, De Costa, BR, Rice, KC (1990). Cannabinoid receptor localization in brain. Proceedings of the National Academy of Sciences of the USA 87, 19321936.
Higgins, JP, Green, S (editors) (2008). Cochrane Handbook for Systematic Reviews of Interventions. Wiley Online Library: Chichester.
Hulicka, IM (1966). Age differences in Wechsler Memory Scale scores. Journal of Genetic Psychology 109, 135145.
Iversen, L (2003). Cannabis and the brain. Brain 126, 12521270.
Jager, G, Kahn, RS, Van Den Brink, W, Van Ree, JM, Ramsey, NF (2006). Long-term effects of frequent cannabis use on working memory and attention: an fMRI study. Psychopharmacology (Berlin) 185, 358368.
Jockers-Scherubl, MC, Wolf, T, Radzei, N, Schlattmann, P, Rentzsch, J, Gomez-Carrillo de Castro, A, Kuhl, KP (2007). Cannabis induces different cognitive changes in schizophrenic patients and in healthy controls. Progress in Neuro-Psychopharmacology and Biological Psychiatry 31, 10541063.
Kambeitz, JP, Bhattacharyya, S, Kambeitz-Ilankovic, LM, Valli, I, Collier, DA, McGuire, P (2012). Effect of BDNF val66met polymorphism on declarative memory and its neural substrate: a meta-analysis. Neuroscience and Biobehavioral Reviews 36, 21652177.
Kanayama, G, Rogowska, J, Pope, HG, Gruber, SA, Yurgelun-Todd, DA (2004). Spatial working memory in heavy cannabis users: a functional magnetic resonance imaging study. Psychopharmacology (Berlin) 176, 239247.
Korver, N, Nieman, DH, Becker, HE, van de Fliert, JR, Dingemans, PH, de Haan, L, Spiering, M, Schmitz, N, Linszen, DH (2010). Symptomatology and neuropsychological functioning in cannabis using subjects at ultra-high risk for developing psychosis and healthy controls. Australian and New Zealand Journal of Psychiatry 44, 230236.
Koskinen, J, Löhönen, J, Koponen, H, Isohanni, M, Miettunen, J (2010). Rate of cannabis use disorders in clinical samples of patients with schizophrenia: a meta-analysis. Schizophrenia Bulletin 36, 11151130.
Lane, SD, Cherek, DR, Lieving, LM, Tcheremissine, OV (2005). Marijuana effects on human forgetting functions. Journal of the Experimental Analysis of Behavior 83, 6783.
Leeson, VC, Harrison, I, Ron, MA, Barnes, TR, Joyce, EM (2012). The effect of cannabis use and cognitive reserve on age at onset and psychosis outcomes in first-episode schizophrenia. Schizophrenia Bulletin 38, 873880.
Linszen, DH, Dingemans, PM, Nugter, MA, Van der Does, AJ, Scholte, WF, Lenior, MA (1997). Patient attributes and expressed emotion as risk factors for psychotic relapse. Schizophrenia Bulletin 23, 119130.
Løberg, E-M, Hugdahl, K (2009). Cannabis use and cognition in schizophrenia. Frontiers in Human Neuroscience 3, 53.
Løberg, EM, Hugdahl, K, Jørgensen, HA (2008). Lower neurocognitive vulnerability in schizophrenia with a history of cannabis abuse? Schizophrenia Research 98, 73.
Lutgens, D, Lepage, M, Iyer, S, Malla, A (2014). Predictors of cognition in first episode psychosis. Schizophrenia Research 152, 164169.
Matochik, JA, Eldreth, DA, Cadet, JL, Bolla, KI (2005). Altered brain tissue composition in heavy marijuana users. Drug and Alcohol Dependence 77, 2330.
McDermott, LM, Ebmeier, KP (2009). A meta-analysis of depression severity and cognitive function. Journal of Affective Disorders 119, 18.
Meier, MH, Caspi, A, Ambler, A, Harrington, H, Houts, R, Keefe, RS, McDonald, K, Ward, A, Poulton, R, Moffitt, TE (2012). Persistent cannabis users show neuropsychological decline from childhood to midlife. Proceedings of the National Academy of Sciences of the USA 109, E2657E2664.
Miles, H, Johnson, S, Amponsah-Afuwape, S, Finch, E, Leese, M, Thornicroft, G (2003). Characteristics of subgroups of individuals with psychotic illness and a comorbid substance use disorder. Psychiatric Services 54, 554561.
Moreno-Granados, JM, Ferrín, M, Salcedo-Marín, DM, Ruiz-Veguilla, M (2014). Neuropsychological assessment of memory in child and adolescent first episode psychosis: cannabis and the «paradox effect». Revista Brasileira de Psiquiatria 7, 1324.
Morrison, PD, Zois, V, McKeown, DA, Lee, TD, Holt, DW, Powell, JF, Kapur, S, Murray, RM (2009). The acute effects of synthetic intravenous Δ9-tetrahydrocannabinol on psychosis, mood and cognitive functioning. Psychological Medicine 39, 16071616.
Moss, HB, Chen, CM, Yi, HY (2013). Early adolescent patterns of alcohol, cigarettes, and marijuana polysubstance use and young adult substance use outcomes in a nationally representative sample. Drug and Alcohol Dependence 136, 5162.
Murray, RM, Lewis, SW (1987). Is schizophrenia a neurodevelopmental disorder? British Medical Journal (Clinical Research ed.) 295, 681682.
Murray, RM, Paparelli, A, Morrison, PD, Marconi, A, Di Forti, M (2013). What can we learn about schizophrenia from studying the human model, drug-induced psychosis? American Journal of Medical Genetics Part B: Neuropsychiatric Genetics 162B, 661670.
Nakamura, EM, Da Silva, EA, Concilio, GV, Adrian Wilkinson, D, Masur, J (1991). Reversible effects of acute and long-term administration of Δ−9-tetrahydrocannabinol (THC) on memory in the rat. Drug and Alcohol Dependence 28, 167175.
Packard, MG, Knowlton, BJ (2002). Learning and memory functions of the basal ganglia. Annual Review of Neuroscience 25, 563593.
Pencer, A, Addington, J (2003). Substance use and cognition in early psychosis. Journal of Psychiatry and Neuroscience 28, 4854.
Penk, WE, Flannery, RB Jr, Irvin, E, Geller, J, Fisher, W, Hanson, MA (2000). Characteristics of substance-abusing persons with schizophrenia: the paradox of the dually diagnosed. Journal of Addictive Diseases 19, 2330.
Pertwee, RG (2008). Ligands that target cannabinoid receptors in the brain: from THC to anandamide and beyond. Addiction Biology 13, 147159.
Pezdek, K, Evans, GW (1979). Visual and verbal memory for objects and their spatial locations. Journal of Experimental Psychology Human Learning and Memory 5, 360373.
Pope, HG, Gruber, AJ, Hudson, JI, Cohane, G, Huestis, MA, Yurgelun-Todd, D (2003). Early-onset cannabis use and cognitive deficits: what is the nature of the association? Drug and Alcohol Dependence 69, 303310.
Pope, HG, Gruber, AJ, Hudson, JI, Huestis, MA, Yurgelun-Todd, D (2001). Neuropsychological performance in long-term cannabis users. Archives of General Psychiatry 58, 909915.
Potvin, S, Joyal, CC, Pelletier, J, Stip, E (2008). Contradictory cognitive capacities among substance-abusing patients with schizophrenia: a meta-analysis. Schizophrenia Research 100, 242251.
Poulsen, HA, Sutherland, GJ (2000). The potency of cannabis in New Zealand from 1976 to 1996. Science and Justice 40, 171176.
Rabin, RA, Zakzanis, KK, Daskalakis, ZJ, George, TP (2012). Effects of cannabis use status on cognitive function, in males with schizophrenia. Psychiatry Research 206, 158165.
Rabin, RA, Zakzanis, KK, George, TP (2011). The effects of cannabis use on neurocognition in schizophrenia: a meta-analysis. Schizophrenia Research 128, 111116.
Ranganathan, M, D'Souza, DC (2006). The acute effects of cannabinoids on memory in humans: a review. Psychopharmacology 188, 425444.
Ruiz-Veguilla, M, Callado, LF, Ferrin, M (2012). Neurological soft signs in patients with psychosis and cannabis abuse: a systematic review and meta-analysis of paradox. Current Pharmaceutical Design 18, 51565164.
Salyers, MP, Mueser, KT (2001). Social functioning, psychopathology, and medication side effects in relation to substance use and abuse in schizophrenia. Schizophrenia Research 48, 109123.
Schnell, T, Koethe, D, Daumann, J, Gouzoulis-Mayfrank, E (2009). The role of cannabis in cognitive functioning of patients with schizophrenia. Psychopharmacology (Berlin) 205, 4552.
Schoeler, T, Bhattacharyya, S (2013). The effect of cannabis use on memory function: an update. Journal of Substance Abuse and Rehabilitation 4, 1127.
Schreiner, AM, Dunn, ME (2012). Residual effects of cannabis use on neurocognitive performance after prolonged abstinence: a meta-analysis. Experimental and Clinical Psychopharmacology 20, 409420.
Smith, K, Flatley, J (2011). Drug misuse declared: findings from the 2010/11 British Crime Survey England and Wales. Home Office Statistical Bulletin 12/11 ( Accessed August 2015.
Smith, MJ, Cobia, DJ, Wang, L, Alpert, KI, Cronenwett, WJ, Goldman, MB, Mamah, D, Barch, DM, Breiter, HC, Csernansky, JG (2014). Cannabis-related working memory deficits and associated subcortical morphological differences in healthy individuals and schizophrenia subjects. Schizophrenia Bulletin 40, 287299.
Sneider, JT, Pope, HG Jr, Silveri, MM, Simpson, NS, Gruber, SA, Yurgelun-Todd, DA (2008). Differences in regional blood volume during a 28-day period of abstinence in chronic cannabis smokers. European Neuropsychopharmacology 18, 612619.
Solowij, N, Battisti, R (2008). The chronic effects of cannabis on memory in humans: a review. Current Drug Abuse Reviews 1, 8198.
Solowij, N, Pesa, N (2010). Cognitive abnormalities and cannabis use. Revista Brasileira de Psiquiatria 32 (Suppl. 1), S31S40.
Song, F, Sheldon, TA, Sutton, AJ, Abrams, KR, Jones, DR (2001). Methods for exploring heterogeneity in meta-analysis. Evaluation and the Health Professions 24, 126151.
Soueif, MI (1976). Differential association between chronic cannabis use and brain function deficits. Annals of the New York Academy of Sciences 282, 323343.
Tait, RJ, Mackinnon, A, Christensen, H (2011). Cannabis use and cognitive function: 8-year trajectory in a young adult cohort. Addiction 106, 21952203.
UN Office on Drugs and Crime (2010). World Drug Report 2010. United Nations Publications: New York.
Vakil, E, Blachstein, H (1997). Rey AVLT: developmental norms for adults and the sensitivity of different memory measures to age. Clinical Neuropsychologist 11, 356369.
Viechtbauer, W (2010). Conducting meta-analyses in R with the metafor package. Journal of Statistical Software 36, 148.
Wadsworth, EJK, Moss, SC, Simpson, SA, Smith, AP (2006). Cannabis use, cognitive performance and mood in a sample of workers. Journal of Psychopharmacology 20, 1423.
Wagner, D, Becker, B, Gouzoulis-Mayfrank, E, Daumann, J (2010). Interactions between specific parameters of cannabis use and verbal memory. Progress in Neuro-Psychopharmacology and Biological Psychiatry 34, 871876.
Wobrock, T, Falkai, P, Schneider-Axmann, T, Hasan, A, Galderisi, S, Davidson, M, Kahn, RS, Derks, EM, Boter, H, Rybakowski, JK (2013). Comorbid substance abuse in first-episode schizophrenia: effects on cognition and psychopathology in the EUFEST study. Schizophrenia Research 147, 132139.
Wojtalik, JA, Barch, DM (2014). An fMRI study of the influence of a history of substance abuse on working memory-related brain activation in schizophrenia. Frontiers in Psychiatry 5, 1.
Yücel, M, Bora, E, Lubman, DI, Solowij, N, Brewer, WJ, Cotton, SM, Conus, P, Takagi, MJ, Fornito, A, Wood, SJ (2012). The impact of cannabis use on cognitive functioning in patients with schizophrenia: a meta-analysis of existing findings and new data in a first-episode sample. Schizophrenia Bulletin 38, 316330.
Yucel, M, Solowij, N, Respondek, C, Whittle, S, Fornito, A, Pantelis, C, Lubman, DI (2008). Regional brain abnormalities associated with long-term heavy cannabis use. Archives of General Psychiatry 65, 694701.


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