By R. Ryan S Patel DO, FAPA OSU-CCS Psychiatrist

Many young people use marijuana for a variety of reasons.

While de-criminalized in many states, the use of cannabis is not without risks. For example, a previous post discussed the negative impact of cannabis on PTSD.

A recent study looked at impact of cannabis use and intelligence.

What were the findings? (1)

  • 1037 individuals born in New Zealand were periodically assessed between ages 7 and 45 years for cannabis use and dependence and with intelligence quotient (IQ) testing (1).
  • At age 45 years, the mean decline in IQ points from childhood to adulthood was greater among long-term users of cannabis (5.5 points) compared with nonusers of cannabis (0.7 points) (1)
  • Deficits were noted in processing speed, learning, and memoryamong adults with long-term cannabis use relative to their childhood assessments (1).

Are there studies on frequency of cannabis use and brain functioning? (2)

  • The use of cannabis 4 or more times per month may impair brain functioning (2).
  • In this small study, students suing cannabis demonstrated poorer verbal learning (p<.01), verbal working memory (p<.05), and attention accuracy(p<.01) compared to non users (2).
  • This might translate to more time studying or less information learned, mistakes, more frustration and angst with school work; and poor academic performance.

Other thoughts:

  • Some people may report cannabis use helping with anxiety, depression, or insomnia when it may just be masking the withdrawal symptoms caused by previous cannabis use.
  • Research shows an association between cannabis use and several medical, cognitive, functional, and psychosocial problems(3).
  • Short-term risks of cannabis use include impaired short-term memory motor dis-coordination, altered judgment, paranoia, and psychosis (4).
  • Other long-term effects of cannabis use include addiction, poor educational outcomes, diminished quality of life, increased risk psychotic disorders, injuries, motor vehicle collisions, and suicide (4,5).
  • Further research is needed on the risk and benefits of specific types and amount cannabis and mental health.
  • It is possible that illegally obtained cannabis may have other harmful substances added to it.

What are some useful resources regarding cannabis?

Treatment Facilities in the Columbus, Ohio area:


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Resources for mental health support can be found here.

Disclaimer: This article is intended to be informative only. It is advised that you check with your own physician/mental health provider before implementing any changes. With this article, the author is not rendering medical advice, nor diagnosing, prescribing, or treating any condition, or injury; and therefore claims no responsibility to any person or entity for any liability, loss, or injury caused directly or indirectly as a result of the use, application, or interpretation of the material presented.


  1. Meier MH, et. al. Long-Term Cannabis Use and Cognitive Reserves and Hippocampal Volume in Midlife. Am J Psychiatry. 2022 May;179(5):362-374. doi: 10.1176/appi.ajp.2021.21060664. Epub 2022 Mar 8. PMID: 35255711; PMCID: PMC9426660.
  2. Hanson KL, et al. Longitudinal study of cognition among adolescent marijuana users over three weeks of abstinence. Addict Behav. 2010 November ; 35(11): 970–976. doi:10.1016/j.addbeh.2010.06.012.
  3. Crean  RD , Tapert SF , Minassian  A , Macdonald  K , Crane  NA , Mason  BJ .  Effects of chronic, heavy cannabis use on executive functions.  J Addict Med. 2011;5(1):9-15. doi:1097/ADM.0b013e31820cdd57
  4. Volkow  ND , Baler RD , Compton  WM , Weiss  SRB .  Adverse health effects of marijuana use.  N Engl J Med. 2014;370(23):2219-2227. doi:1056/NEJMra1402309
  5. Carvalho  AF , Stubbs B , Vancampfort  D ,  et al.  Cannabis use and suicide attempts among 86,254 adolescents aged 12-15 years from 21 low- and middle-income countries.  Eur Psychiatry. 2019;56:8-13. doi:1016/j.eurpsy.2018.10.006

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Posted by R. Ryan Patel DO, FAPA OSU CCS Psychiatrist at 2:08pmPosted in CannabisCannabis and mental health Tagged cannabis gradescannabis mental healthmarijuana brain functionmarijuana grades

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