Latest Research

A recent article covering a broad spectrum of marijuana research appeared in The New England Journal of Medicine on June 5, 2014.   Nora D. Volkow, M.D., Ruben D. Baler, Ph.D., Wilson M. Compton, M.D. and Susan R. B. Weiss, Ph.D,  wrote an article, “The Adverse Effect of Marijuana Use.”  Here’s a summary of key issues concerning our nation’s children:

* 9% of those who experiment with marijuana will become addicted. The number goes to 1 in 6 for those who begin as teens.   The medical community recognizes cannabis withdrawal syndrome.

* The brain, including the endocannabinoid system under goes active development during adolescence.  Early and regular use increase the likelihood of addiction or other illicit drug usage.

*  Compared to those who begin marijuana usage in adulthood, those who begin in adolescence are 2-4 times more likely to have symptoms of cannabis dependence within 2 years after first use.

* Compared with those unexposed to marijuana, adults who smoked regularly during adolescence have impaired neural connectivity in specific brain regions: the precuneus; the fimbria (for memory); the prefrontal networks (responsible for executive function), the nucleus accumbens (reward circuit and addiction) and the subcortical networks (processing habits and routines).

* The negative effects on the functional connectivity of the brain is particularly prominent if use starts in adolescence or young adulthood.

* Marijuana use is also linked to psychosis and worsens the course of illness in patients with schizophrenia.  Heavier use, greater potency and exposure at younger ages affect the course and onset of disease, advancing the time of 1st psychotic episode by 2-6 years.

* The risk  for drivers with over 1 ng. THC per milliliter of blood were 3 to 7 times as likely to to be responsible for an accident as those with no alcohol or drugs taken before driving.

* Regular marijuana use in teen years, in addition to environmental factors such as poverty,  increases the likelihood of poor academic achievement, dropping out of school and chronic unemployment and criminal behavior.   Some studies show cognitive effects may be reversible, but other studies show the deficits persist.

* Regular marijuana use is associated with an increased risk of anxiety and depression.  The correlation is there, but the cause has not been established.

* There is an association with marijuana usage and lung cancer, but it may not be as strong as it is for tobacco.  The likelihood of heavy marijuana usage contributing to chronic bronchitis.

* There’s an association between vascular conditions that increase risk of heart attacks and strokes during marijuana intoxication.

(A complete summary is online. Sources and footnotes are quoted in the article, see pp. 2219-2227.)


Bursting the Bubble of Marijuana Hype