Cannabis and Special Risk Populations
Cannabis may not be suitable for all patients.
Cannabis and Special Risk Populations
Cannabis may not be suitable for all patients.
Print PDF

Cannabis may not be suitable for all patients. Several publications from Health Canada, the CFPC, and others, have identified a set of special-risk populations in the context of both medical and recreational cannabis use. 1,2,3,4,5,6,7,8 More Level 1 research is needed on both the therapeutic and adverse effects of cannabis for specific presentations and populations.

This resource provides an overview of the risks of cannabis use in the following commonly-cited populations:

  • Women who are pregnant, breastfeeding, or planning to become pregnant
  • Children and youth under 25 years
  • Individuals with current, past, or family history of psychosis
Pregnant women and fetuses
  • If a woman consumes cannabis while pregnant, she will expose the fetus to delta-9-tetrahydrocannabinol (THC)—the primary psychoactive component in cannabis—through her bloodstream.6,12
  • A 2016 systematic review and meta-analysis of evidence shows that fetuses exposed to THC are more likely to experience decreased birth weight and increased placement in NICU/ICU. 9
  • Evidence shows that women who consume cannabis during pregnancy have a greater risk of anemia. 9
  • Acute effects of cannabis consumption include a decrease in blood pressure, which may increase the risk of falls causing injury to both mother and fetus. 6
  • Findings from two prospective longitudinal cohort studies show that heavy in utero exposure (at least 5 times per week) to THC can negatively effect children’s neurocognitive development. 10,11,12 These effects include but are not limited to:
    • hyperactivity
    • deficits in memory, verbal and visual reasoning, verbal skills
    • reduced academic achievement
    • increased risk of early initiation of substance abuse
  • Because cannabis use is often concurrent with alcohol and tobacco use, most research has been unable to isolate the effects of cannabis use exclusively. There are studies, however, that point to higher instances of negative effects on the fetus when cannabis and tobacco are combined during pregnancy (compared to either cannabis or tobacco alone).12,13,14
Breastfeeding women
  • THC is stored in fatty tissues and accumulates in breast milk. Recent studies have shown that the THC in breast milk is subsequently metabolized by breastfeeding babies. 6,12,15
  • Several reports indicate that babies exposed to THC in breastmilk may experience negative short-term effects, including: 15,16
    • lethargy
    • reduced muscle tone
    • poor feeding habits
Women attempting to conceive
  • There is limited evidence that suggests cannabis consumption may negatively impact a woman’s ability to conceive by: 6,17,18,19
    • disrupting hormonal regulation and menstrual cycles
    • reducing movement of ova through the oviducts
    • decreasing success of in vitro fertilization.
  • Research has also shown that regular (at least once weekly) cannabis consumption by males can decrease sperm count by up to 29%. 6,20
Under the age of 25
  • The human brain continues to develop until the age of 25. Multiple sources have established that regular cannabis use during adolescence and early adulthood can cause functional and structural changes to the brain, impairing its development. 2, 7, 21, 22, 23, 24
Children
  • Cannabis is not appropriate for medical use in pediatric populations except in very specific circumstances, including certain forms of refractory epilepsy (e.g., Dravet syndrome). 25
  • Cannabis use during adolescence has been associated with:
    • increased risk of cannabis use disorder (approximately one in six) 26, 27
    • increased risk of developing mental health problems, including anxiety, depression, psychosis, and schizophrenia 21, 28, 29, 30, 31, 32
    • increased risk of cognitive deficits and poorer school performance 21, 33, 34
  • Cannabis use increases the risk of psychosis. Individuals who have used cannabis in their lifetime have a 40% higher risk of developing a psychotic outcome than those who have not used cannabis. 8, 21, 35, 36, 37
Risk Factors
Use in Adolescence
  • Individuals who begin using cannabis before the age of 16 have a higher risk of developing nonaffective psychosis compared to those who started cannabis use later, or who never used cannabis.7,38
  • More than 50% of youth who develop psychotic symptoms from cannabis use will develop a future psychotic disorder. 32
  • Psychiatric patients who use cannabis during adolescence and early adulthood experience their first psychotic episode three to six years earlier compared to those who do not use cannabis. 8,19, 37, 39
Frequent Use
  • There is a direct dose relationship between frequent cannabis use and the risk of developing psychosis and schizophrenia.8,42,40,42
  • Individuals who use cannabis daily are two to three times more likely to be at risk of developing psychotic disorders than those who do not use cannabis.8,41
High THC Potency
  • Individuals who use cannabis products with a high THC potency (16% average) on a daily basis are at a greater risk of experiencing a psychotic episode. They also experience their first psychotic episode earlier than both non-users and daily users of less-potent cannabis products. 37
Genetic Predisposition to Psychotic Disorders
  • Cannabis use has been shown to trigger or amplify a genetic predisposition to psychotic disorders.2,7,36,42
  • For individuals with a first-degree relative who has a history of psychosis, consuming cannabis daily could increase the risk of developing a psychotic disorder by up to ten times.8,42
Print PDF
References

1 Hodgson, C, Zacharias R. Who shouldn’t use cannabis?: Evidence Brief. Michael G. DeGroote Centre for Medical Cannabis Research. Hamilton, ON; 2017. cited 26 Sep 2018.

2 Fischer B, Russell C, Sabioni P, van den Brink W, Le Foll B, Hall W, et al. Lower-Risk Cannabis Use Guidelines: A Comprehensive Update of Evidence and Recommendations. Public Health Policy. 2017;107(8):e1-e12.

3 Kahan M, Srivastava A, Spithoff S, Bromley L. Prescribing smoked cannabis for chronic noncancer pain. Canadian Family Physician. 2014;60:1083-1090.

4 Government of Canada. Is cannabis safe to use? Facts for young adults aged 18-25 years: Cannabis evidence Brief. Health Canada. Ottawa, ON; 2018 cited 26 Sep 2018.

5 Government of Canada Evidence Brief: Is cannabis safe to use? Facts for youth aged 13-17 years: Cannabis evidence Brief. Health Canada. Ottawa, ON; 2018 cited 26 Sep 2018.

6 Government of Canada Evidence Brief: Is cannabis safe during preconception, pregnancy, and breastfeeding?: Cannabis evidence Brief. Health Canada. Ottawa, ON; 2018 cited 26 Sep 2018.

7 Lenroot RK, Giedd JN. Brain development in children and adolescents: Insights from anatomical magnetic resonance imaging. Neurosci Biobehav Rev 2006;30(6):718–29.

8 Government of Canada. Does cannabis use increase the risk of developing psychosis or schizophrenia?: Cannabis evidence brief. Health Canada. Ottawa, ON; 2018 cited 26 Sep 2018.

9 Gunn JK, Rosales CB, Center KE, Nunez A, Gibson SJ, Christ C, Ehiri JE. Prenatal exposure to cannabis and maternal and child health outcomes: A systematic review and meta-analysis. BMJ Open 2016 Apr 5; 6(4):e009986,2015-009986

10 Fried P. Ottawa Prenatal Prospective Study, 1995, 2002.

11Day N, Richardson G.  Maternal Health Practices and Child Development Study, 1991.

12 Porath AJ, Konefal S, Kent P. Clearing the smoke on cannabis: Maternal cannabis use during pregnancy—an update. Ottawa, ON: Canadian Centre on Substance Use and Addiction; 2018 cited Sep 24 2018.

13 Chabarria KC, Racusin DA, Antony KM, et al. Marijuana use and its effects in pregnancy. Am J Obstet Gynecol 2016;215:506.e1-7.

14 El Marroun H, Tiemeier H, Steegers E, Jaddoe V, Hofman A, Velhulst FC. Intrauterine cannabis exposure affects fetal growth trajectories: The generation R study. Journal of the American Academy of Child & Adolescent Psychiatry Dec 2009; 48(11): 1173-1181.

15 Liston J. Breastfeeding and the use of recreational drugs--alcohol, caffeine, nicotine and marijuana. Breastfeed Rev 1998 Aug;6(2):27-30.

16 Djulus J, Moretti M, Koren G. Marijuana use and breastfeeding. Can Fam Physician. 2005 Mar 10; 51(3): 349–350.

17 Klonoff-Cohen HS, Natarajan L, Chen RV. A prospective study of the effects of female and male marijuana use on in vitro fertilization (IVF) and gamete intrafallopian transfer (GIFT) outcomes. Am J Obstet Gynecol 2006 Feb;194(2):369-76

18 Brents LK. Marijuana, the endocannabinoid system and the female reproductive system. Yale J Biol Med 2016 Jun 27;89(2):175-91. 15.

19 Sharma R, Biedenharn KR, Fedor JM, Agarwal A. Lifestyle factors and reproductive health: Taking control of your fertility. Reprod Biol Endocrinol 2013 Jul 16;11:66,7827-11-66

20 Gundersen TD, Jorgensen N, Andersson AM, Bang AK, Nordkap L, Skakkebaek NE, Priskorn L, Juul A, Jensen TK. Association between use of marijuana and male reproductive hormones and semen quality: A study among 1,215 healthy young men. Am J Epidemiol 2015 Sep 15;182(6):473-81.

21 Grant CN, Belanger RE, Canadian Paediatric Society, Adolescent Health Committee. Position Statement: Cannabis and Canada’s children and youth. Paediatr Child Health 2017;22(2):98-102. cited Sep 21 2018.

22 Jacobus J, Tapert SF. Effects of cannabis on the adolescent brain. Curr Pharm Des. 2014;20(13): 2186–2193.

23 Lisdahl KM, Gilbart ER,Wright NE, Shollenbarger S. Dare to delay? The impacts of adolescent alcohol and marijuana use onset on cognition, brain structure, and function. Front Psychiatry. 2013;4:53.

24 Volkow ND, Swanson JM, Evins AE, et al. Effects of cannabis use on human behavior, including cognition, motivation, and psychosis: A Review. Jama Psychiatry 2016 73 (3): 292-97.

25 Rieder MJ. Is the medical use of cannabis a therapeutic option for children? Canadian Pediatric Society Position Statement. Paediatr Child Health 2016; 21 (1): 31-34.

26 Turner SD, Spithoff S, Kahan M. Approach to cannabis use disorder in primary care: Focus on youth and other high-risk users. Can Fam Physician 2014;60(9):801–8, e423–32.

27 Volkow ND, Baler RD, Compton WM, Weiss SR . Adverse health effects of marijuana use. N Engl J Med 2014;370(23):2219–27.

28 Buckner JD, Schmidt NB, Lang AR , Small JW, Schlauch RC, Lewinsohn PM. Specificity of social anxiety disorder as a risk factor for alcohol and cannabis dependence. J Psychiatr Res 2008;42(3):230–9.

29 Cornelius JR , Kirisci L, Reynolds M, Clark DB, Hayes J, Tarter R . PTSD contributes to teen and young adult cannabis use disorders. Addict Behav 2010;35(2):91–4.

30 Johns A. Psychiatric effects of cannabis. Br J Psychiatry 2001;178:116–22.

31 D’Souza DC, Perry E, MacDougall L, et al. The psychotomimetic effects of intravenous delta-9-tetrahydrocannabinol in healthy individuals: Implications for psychosis. Neuropsychopharmacology 2004;29(8):1558–72.

32 Arendt M, Rosenberg R , Foldager L, Perto G, Munk-Jørgensen P. Cannabis-induced psychosis and subsequent schizophrenia-spectrum disorders: Follow-up study of 535 incident cases. Br J Psychiatry 2005;187(6):510–5.

33 Lynskey MT, Coffey C, Degenhardt L, Carlin JB, Patton G. A longitudinal study of the effects of adolescent cannabis use on high school completion. Addiction 2003;98(5):685–92.

34 Brook JS, Stimmel MA, Zhang C, Brook DW. The association between earlier marijuana use and subsequent academic achievement and health problems: A longitudinal study. Am J Addict 2008;17(2):155–60.

35 Batalla A, Bhattacharyya S, Yucel M, Fusar-Poli P, Crippa JA, Nogue S, Torrens M, Pujol J, Farre M, Martin-Santos R. Structural and functional imaging studies in chronic cannabis users: A systematic review of adolescent and adult findings. PLoS One 2013;8(2):e55821.

36 Large M, Sharma S, Compton MT, Slade T, Nielssen O. Cannabis use and earlier onset of psychosis: A systematic meta-analysis. Arch Gen Psychiatry 2011 Jun;68(6):555-61.

37 Di Forti M, Sallis H, Allegri F, Trotta A, Ferraro L, Stilo SA, Marconi A, La Cascia C, Reis Marques T, Pariante C, et al. Daily use, especially of high-potency cannabis, drives the earlier onset of psychosis in cannabis users. Schizophr Bull 2014 Nov;40(6):1509-17.

38 McGrath J, Welham J, Scott J, et al. Association between cannabis use and psychosis-related outcomes using sibling pairanalysis in a cohort of young adults. Arch Gen Psychiatry. 2010;67(5):440–447.

39 Helle S, Ringen PA, Melle I, Larsen TK, Gjestad R, Johnsen E, Lagerberg TV, Andreassen OA, Kroken RA, Joa I, et al. Cannabis use is associated with 3 years earlier onset of schizophrenia spectrum disorder in a naturalistic, multi-site sample (N=1119). Schizophr Res 2016 Jan;170(1):217-21.

40 Marconi A, Di Forti M, Lewis CM, Murray RM, Vassos E. Meta-analysis of the association between the level of cannabis use and risk of psychosis. Schizophr Bull 2016 Feb 15.

41 Fergusson DM, Horwood LJ, Ridder EM. Tests of casual linkages between cannabis use and psychotic symptoms. Addiction 2005 Mar;100(3):354-66.

42 Radhakrishnan R, Wilkinson ST, D'Souza DC. Gone to pot - A review of the association between cannabis and psychosis. Front Psychiatry 2014 May 22;5:54.

Last updated: November 15, 2018