So where are we on this marijuana issue? Has smoking marijuana become a rite of passage for American youth — no harm, no foul?
Fourteen-time Olympic gold medalist Michael Phelps quickly offered this apology after photographs of him apparently smoking marijuana at a college party in November were published recently:
"I'm 23 years old and despite the successes I've had in the pool, I acted in a youthful and inappropriate way, not in a manner people have come to expect from me. For this, I am sorry. I promise my fans and the public, it will not happen again."
Full disclosure here. Like many journalists, I have moonlighted in my career. One job in the 1970s was with a New York nonprofit that produced monographs on health problems associated with marijuana use.
Based on that experience, I can testify that it has never been popular to discuss marijuana's debilitating effects on people. In fact, it's even harder to talk about it now, since 12 states approve of pot use for medicinal purposes.
Over the years, I have interviewed countless chronic marijuana users. Virtually all admitted, usually with a laugh, that their thinking is fuzzier than they wish it were. They have short attention spans and poor memory retention. They spent too many days obsessing about getting high and too many nights stoned in front of a television. One man said he spent $50,000 a year on weed.
In May, I interviewed a teen who said smoking marijuana caused her depression to spiral downward until she started planning to take her own life. Her desperate parents got her into a Michigan substance-abuse treatment center, where she escaped her pot habit and rediscovered a desire "to live a life that is productive."
Happily, pot use is declining among U.S. youth.
In 1980, 60 percent of high school seniors said they had tried pot, but that figure fell to 42 percent in 2008, according to the Monitoring the Future survey.
Pot experimentation is similarly down in younger grades. In 2008, 15 percent of eighth-graders and 30 percent of 10th-graders said they had tried pot. (In the mid-1990s, these figures were 23 percent and 42 percent, respectively.)
Moreover, among high school students of all ages, there's strong "disapproval" of both regular and occasional marijuana use.
Trends like these give hope to people who want to see America's youth culture become largely drug-free, like it was before the hippies, yippies and dippies came onstage.
What can families do to steer their children away from marijuana entanglements? Stay connected, says the National Longitudinal Study on Adolescent Health (Add Health), the nation's largest and most comprehensive study of teens.
Teens who feel connected to their parents are more likely to say "no thanks" to marijuana, Add Health researchers found. Part of that connectedness, they added, means having a parent home before and after school, at dinnertime and at bedtime.
Other protective influences for teens are to feel connected to adults and peers at school, and have solid self-esteem, good grades and a religious identity.
To me, the big question is whether the massive, 78-million-strong Generation Y is going to kick America's illegal drug problems to the curb.
In 2007, drug czar John Walters told me that while baby boomers viewed illicit drugs as "new and rebellious," today's teens see them as something "for losers." If Mr. Walters is right — and I hope he is — that indicates a brilliant future for our nation. It's also a not-too-subtle hint for Mr. Phelps to be sure to keep his promise.
• Cheryl Wetzstein can be reached at firstname.lastname@example.org.