How Strong is Link Between Cannabis Use, Mental Health Effects?

Among the nearly 100 conclusions about the therapeutic benefits and risks of cannabis/cannabinoid use made by the National Academies were numerous findings in the mental health arena. Below are the conclusions that have at least moderate evidence (that is, enough data to make general conclusions, but with enough risk of chance, bias, or confounding factors to not rule out other explanations).

There are enough data to draw firm conclusions of the following, with a limited risk of other explanations due to chance, bias, or confounding factors:

• Cannabis use is associated with the development of schizophrenia and other psychoses.

• Starting cannabis use earlier in life increases the risk of problem cannabis use.

• Stimulant use in teenagers with attention-deficit/hyperactivity disorder (ADHD) is not a risk factor for problem cannabis use.

There is moderate evidence of the following:

• Cannabis use increases symptoms of mania and hypomania in people with bipolar disorder.

• Cannabis use is associated with an increased risk of developing depression, and depression is a risk factor for developing problem cannabis use.

• Cannabis use is associated with increased incidences of suicidal ideation, attempts, and completion.

• Regular cannabis use is associated with an increased incidence of social anxiety disorder.

• Anxiety disorders, personality disorders, and bipolar disorder are not risk factors for problem cannabis use.

• Adolescent ADHD is not a risk factor for problem cannabis use.

• Problem cannabis use is associated with increased severity of PTSD symptoms. ■