Research increasingly confirms that marijuana use is harmful. Acute symptoms of marijuana intoxication include impaired short-term memory, attention, judgment, and cognitive function, as well as increased heart rate.¹ Symptoms that can persist for weeks after the immediate effects of marijuana have worn off include insomnia and, possibly, impaired memory and learning.² When continued over years, a pattern of heavy, daily, or almost daily use can increase some health risks, including marijuana dependence, chronic cough or respiratory impairment, cardiovascular disease, and adverse effects on psychosocial development and mental health.^2,3

The long-term effects of marijuana use on adults who initiated use as adolescents are especially striking. If marijuana use begins in adolescence when the brain is still developing, the negative impact of chronic marijuana use on cognitive function and structure can last several years and may be permanent.^3,4 For example, one study of marijuana users who began using in adolescence revealed deficits in the areas of the brain responsible for learning and memory,⁵ which can, in turn, impact an adolescent’s ability to successfully function in the contexts of school, work, and family.^1,3 Another study showed that among persistent adult marijuana users, those who started using marijuana in their youth lost as many as 8 IQ (intelligence quotient) points between the ages of 13 and 39. These lost cognitive abilities were not restored in those who quit using marijuana as adults.³

Recent data from a government report called TEDs from the (Substance Abuse & Mental Health Services Administration) SAMHSA