For most American youth, there was a time when “getting high” meant climbing a tree or swinging in a playground. Now it has quite a different meaning, though some more critically refer to it as an obsession.

Monitoring the Future (MTF), an annual project of the University of Michigan Institute for Social Research, is a long-term study of American adolescents, college students, and adults through age 50.

Recognizing that smoking, drinking, and illicit drug use are leading causes of morbidity and mortality, during adolescence and later in life, MTF annual reports are uniquely designed to generate data to provide an accurate picture of their use.

Though alcohol remains the teen drug of choice, surveying eighth, 10th- and 12th-graders, the latest MTF report finds that marijuana use among teens is rising. After a period of decline in usage, teen marijuana use has been steadily increasing over the last decade.

Some experts express concern that recent marijuana legalization in several states may further increase teen use, reduce perception of risk, and enhance availability.

Though some users disagree, both marijuana and alcohol are addictive drugs says the National Institute on Drug Abuse (NIDA). User denial notwithstanding, use of any addictive drug has negative consequences.

MTF reports that 10 percent of marijuana users are addicted, while nearly 17 percent of those who begin using as teens are addicted. Between 25 and 50 percent of daily users are addicted (6.5 percent of high school seniors report daily use).

Containing over 400 chemicals, the main psychoactive ingredient found in marijuana is delta-9-tetrahydrocannabinol (THC). All forms of marijuana are mind-altering, changing how the brain works.

Interfering with both learning and memory, THC finds brain cells, or neurons, with specific receptors called cannabinoid receptors, and binds to them. Slowing reaction time and impairing judgment, marijuana affects brain function, compromising the ability to perform complex tasks, including academics and other activities requiring focus.

The negative effects from marijuana, including those upon memory and learning, can last for days and sometimes weeks. Tests find that THC can be detected days later in the system of the user. NIDA declares that daily users are “functioning with a dimmed-down brain most or all of the time.”

Marijuana use has an immediate physical effect, including increased heart rate. Blood vessels in the eyes expand, making eyes look red.

Its relationship to impaired driving is well documented. But studies find that early usage of marijuana may affect mental health, and some users experience acute psychotic reaction or panic attack while under the influence. Frequent users risk injury to the lungs or other respiratory ailment.

A recent Duke University study concludes that marijuana use among teens may cause a lasting and irreversible IQ loss, even with later discontinuation of use. “Marijuana is not harmless, particularly for adolescents,” said Duke researcher Madeline Meier.

With more teens using marijuana, researchers express concern that a growing proportion of the population will be affected. Meier added, “Continued high use of marijuana among today’s teens increases concerns about the potential public health impact of marijuana on teens’ brains.”

With use of alcohol and marijuana a serious health problem here, it’s time our community got serious about addressing these youthful public health threats. We can no longer ignore what they are doing to our children.

Ronald E. Bogle is a retired Superior Court judge.