When it comes to drug and alcohol abuse among teenagers, peer pressure and experimentation frequently are cited as contributors. But according to one expert, a look at adolescent brains shows why teens are particularly affected by drug and alcohol use.

To speak more about what’s going on in teenagers’ heads — and how it affects things like substance addiction — Dr. Traci L. Brooks is coming to the Vineyard next week for three presentations about “The Adolescent Brain” and changes that occur as the brain matures.

Dr. Brooks, director of adolescent medical services at the Cambridge Health Alliance, will speak to parents and community members Wednesday evening at the high school’s performing arts center. Earlier in the day, she will address faculty and students at the high school’s Wellness Day. The appearances are sponsored by the Youth Task Force.

Beyond learning about their brains, Wellness Day allows students to choose from a wide menu of workshops, ranging from Tong Ren energy therapy to Longsword dancing, which was common in medieval England, to heart-rate-variability biofeedback and nutritional survival skills for college.

Dr. Brooks will speak to all the students during an assembly. “The adolescent brain is actually undergoing a growth spurt,” Dr. Brooks said in an interview with the Gazette this week. While motor skills are developed earlier, she said, things like abstract thought and memory formation are formed later, with the brain continuing to develop until age 25.

Because of this, she said, substance abuse is especially detrimental to teenagers, particularly in terms of becoming dependent. “If the brain is exposed to alcohol and drugs during the time of the growth of the frontal cortex,” she said, “there is the risk of long-term dependence on substances . . . the brain starts to think, ‘Oh, this is normal.’”

Studies have shown, “the earlier you start a substance, the more likely you are to become dependent upon that substance,” Dr. Brooks added. For example, those that use marijuana at the age of 13 or earlier, she said, have a 17 per cent likelihood of becoming dependent. For those 19 or older, those odds fall to 4 per cent, she said.

Drugs also have short term, immediate effects, she said, and can affect short- and long-term memory foundation.

Additionally, she said, teenagers lack inhibiting processes, and they are more likely to experiment: a recipe for dependence.

Dr. Brooks’s work focuses on prevention and education, including how to better educate clinicians and how to get information from adolescents with brief screenings.

When it comes to prevention, she said, providing teenagers with details about the brain’s growth process can help in the exchange of such information. Teens “respond better” than when they are simply told “just don’t do [drugs],” Dr. Brooks said.