Thursday, September 24, 2009

Post #21--Would a Split Drinking Age Be Better?

A new study of the drinking age (Males, 2008) apparently finds that a split (or "graduated") drinking age of 18 for beer/wine and 21 for liquor would reduce combined violent deaths (traffic crash deaths plus homicides) among 18-20 year olds with similar reductions for 16-17 year olds and 21-24 year olds. It studied the effects over time of raising the age to 21 in the 1980s, based on a state's former drinking age (18 for all beverages, 18 for beer/wine only, or 19 and 20), relative to states that were 21 throughout. When they were raised to 21, the ones that were previously 18 for all beverages, as well as the former 19 and 20 states, saw a decrease in combined deaths, mainly from traffic crashes. But the 11 states that were 18 for beer and/or wine only, they saw an increase in deaths, with the lion's share of the increase being homicides. Interestingly, a few states that were 18 for all beverages saw increases or no significant change as well when the ages were raised to 21.

What are we to make of all this? Several states had split drinking ages, many of which had them for decades. When we look at the dates that the 21 law became effective, we see that all of them but Oklahoma (1983) raised them in 1985 or later. Ditto for the "18 for all beverages" states that saw increases or no significant changes. Hmmmm....what happened around that time? In 1984, the federal government coerced the states with lower drinking ages to raise them to 21 or lose 10% of annual highway funding starting in 1988. So, it could simply be that for many of the coerced states, raising their drinking ages merely threw gasoline on the fire!

This interpretation, rather than anything special about a split drinking age, appears to be more likely to be true when we consider a study by Miron and Tetelbaum (2009). In their study, which controlled for more variables than Males (2008) but looked only at traffic fatalities, they separated out the states based on the year the drinking age was raised to 21. The states that were coerced (i.e. those who raised the age after 1984) overall saw no lifesaving effect. On the other hand, the ones that raised their drinking ages voluntarily in 1983 or earlier did see a small lifesaving effect, but that only lasted a year or two and then wore off. Robustness checks were done as well. Interestingly, Miron and Tetelbaum found no clear relationship for the purchase ages of various beverage types when measured separately, but they did find an increase in fatalities among drivers under 18 when the drinking age was 19, 20, or 21 as opposed to 18.

We at 21 Debunked therefore see no reason why a split drinking age is superior to a drinking age of 18 across the board. We would support the former as a steppingstone to the latter, but ultimately favor the latter hands down. We never understood it since you can get just as drunk on one as you can on the other, and beer is grosslly overrepresented in DUI fatalities. If states feel that they must have special restrictions for 18-20 year olds, which are probably unnecessary, one or more of the following may make more sense:
  • Keep the age at 21 for kegs, cases, and other bulk quantities of alcohol; let 18 year olds buy everything else.
  • Limit the quantities 18 year olds can buy off-premise to 216 ounces of beer, 1 gallon of wine, or 1 fifth of liquor per person per day.
  • Require 18-20 year olds (or even just 18 year olds) to sign a logbook upon purchase, similar to what is done for Sudafed at all ages.
  • Have kegs and cases be sold only in beer distributors regardless of age, making the first two things easier to enforce.
  • Keep it 21 for internet alcohol orders, like some states currently do with cigarettes.
  • Have shorter trading hours (beginning later and/or ending earlier) for off-premises sales for 18 year olds than for those over 19 (or 20 or 21).
  • Allow some bars to set the limit higher than 18 if they wish (no new law needs to be made).
Also, we feel that the age limit should be the same for on- and off-premise sales, at 18. If we let 18 year olds buy cigarettes and guns for off premise use, why not a 6-pack? Their younger friends will find a way to get booze either way, and both 8th graders and 10th graders currently find alcohol easier to get than cigarettes. Furthermore, if there is a wide gap between the two (i.e. 18 for bars and 21 for stores), that may perversely encourage drunk driving for those rural 18-20 year olds whose nearest bar is 10+ miles away while a store that sells 6-packs is a mere 500 feet away. However, such perverse incentives could in theory be minimized by letting 18 year olds have the same drinking rights as 21 year olds currently enjoy, with the one exception being off-premise purchase, and having that purchase age be 19 instead of 21. We don't have any studies to back this up, but we also know of no hard evidence that it is any safer than 18 across the board.

In contrast, there is some evidence that restricting bulk alcohol sales may have benefits. A study of college students in college towns by Kuo et al. (2003) found that the availability of 6-packs was negatively associated with self-reported "binge" drinking, 12-packs showed no effect, while 24-packs (cases), 30-packs, and kegs all showed significant positive associations. In other words, the more 6-packs available, the less "binge" drinking. The more cases and kegs, the more "binge" drinking. (Liquor and wine were not studied; nor were 18-packs.) They also found that beer price was inversely related to "binge" drinking, and store advertising was directly related, just as expected. While we were unable to locate any jurisdiction in the world that has age-specific bulk-only alcohol restrictions, it stands to reason that such a thing would make more sense than splitting the age by venue or beverage type regardless of quantity.

Monday, September 21, 2009

The Truth Should Be Self-Evident--Not All "Bingers" are Created Equal

Binge drinking. We all have heard the term used incessantly in the media, who usually claim it is getting worse. Our kids are out of control, they say, and we need to get tougher. Except, of course, when the issue of the 21 drinking age comes up--then it has gone way down, and the raising of the drinking age in the 1980s gets all (or nearly all) the credit.  Predictable to say the least.

So which is it? It depends on your definition of "binge" drinking. The term originally meant a multi-day, very heavy drinking session in which the drinker neglects usual responsibilities and behaves recklessly--also known as a bender. Fortunately, very few people do this, both now and back in the day. But in 1994, Henry Wechsler of the Harvard University School of Public Health redefined the term to mean anytime someone drinks 5 or more drinks in the same evening, later modified to be 4 or more for a woman. This "5/4 definition" is the one most commonly used nowadays, with the gender-neutral 5+ definition a close second since the latter has been tracked by national surveys since 1975. And yes, it (defined this way) has gone down since its peak in 1979 for everyone except college students and non-college females. But that downward trend began several years before a significant number of states raised their drinking ages to 21, and also occurred in states that stayed 21 throughout.

But is it really an accurate index of harmful drinking? That question appears to have been answered fairly in a new study. Using self-reported alcohol-related injuries (major or minor) in the past 6 months as the dependent variable, researchers examined the effect of the number of drinks per drinking day, and the frequency of occasions having that number of drinks in the past month, among college students. This clearly makes more sense than lumping them all together, or looking only at total volume or frequency. Results were that risks increase rapidly after consuming 8+ drinks (males) or 5+ (females), on at least four days per month. Effects were further magnified among those who scored high on sensation-seeking. It was also found that the 5/4 definiton loses much of its predictive power when days of 8/5+ are removed from the equation. And remember, none of these models account for speed or context of drinking, or even distinguish drunk driving, and students often undercount their drinks as well (due in part to the ubiquitous "red party cups" and the popularity of hard liquor).  But one benefit to this study is that body weight was controlled for, since the effect of a specific number of drinks varies widely across individuals.

Another recent study found that a 7/6+ cutoff was far more predictive of alcohol-related problems (relative to non-bingers) than a 5/4+ one.  Those who met the 5/4+ cutoff but not the 7/6+ one averaged 5.4 drinks per occasion, while those who met the 7/6+ cutoff averaged a whopping 9.1 drinks.  In terms of negative consequences, those males who typically drank 5-6 drinks (and 4-5 for females) generally did not fare significantly worse than the nonbingers, but the heavier 7/6+ group clearly did.

Clearly, the 5/4 definition is an arbitrary convention with little to no scientific basis. Kind of like, well, the 21 drinking age. An ideal definition would take into account context, speed, and BAC, set at rational thresholds. However, a quick, context-neutral, numerical definition is needed for survey purposes. While for the vast majority of the college-age population a 5/4+ threshold is a good negative test for acutely dangerous drinking, a 10/8+ threshold is a better sufficient test for the same, and intermediate between the two is an 8/6+ threshold.  Thus, we at 21 Debunked propose two thresholds: 8/6+ drinks and 10/8+ drinks. It's probably best to jettison the word "binge" entirely--call the first threshold "heavy episodic drinking" or "high risk drinking," and the second one "extreme drinking." Unfortunately, these have not been measured very well over time, so to answer the first question, we don't know for sure.

But if we are to go with anecdotal data and statistical proxies for extreme drinking, we can probably safely that say such drinking has been on the rise, at least for college students. For example, another study found that between 1998 to 2005, there was a significant increase in alcohol-related nontraffic deaths among students, driven by a near tripling of alcohol poisoning deaths. (The actual statistics were simply those for 18-24 year olds multiplied by 30%, so this actually includes many non-students as well) That being said, we should note that the majority of college drinkers still drink responsibly, whether legally or illegally, and only a small minority drinks to these ludicrously high levels. However, the latter appears to be where the real problems lie, and where our efforts are best concentrated.  But we still keep on barking up the wrong tree time and again.

It's also worth noting that in the first study mentioned, participants from 3 out of the 4 American universities surveyed had higher rates of alcohol-related injury than those from the one Canadian university, though the difference was not statistically significant.  It is quite plausible that the 21 drinking age, by forcing drinking underground, exacerbates such problems. (Canada's drinking age is 18 or 19, depending on the province)

We at Twenty-One Debunked do not endorse any kind of drinking, underage or otherwise, and we do not mean to imply that drinking below a specific threshold is safe for everyone. To our knowledge, no such absolute threshold exists. But we do think that we need to get our priorities straight as a society when it comes to drinking.  America's young people--our future--deserve nothing less.

Latest Bit of Scarelore--Is it True?

In a desperate attempt to hang on for dear life, knowing its days are numbered, the pro-21 crowd is recycling an old fear: that alcoholism rates would increase dramatically if the drinking age is lowered below 21. And they now have a study to "prove" it, or so they say.

The study pools data from both a 1992 survey and a 2002 survey, and finds that those who were exposed to a drinking age of less than 21 when they were ages 18-20 were about 1.3 times more likely to have an alcohol use disorder, and about 1.7 times more likely to have a substance use disorder other than alcohol, in the past year. Even (scratch that, especially) when the respondents were in their 40s and 50s. The researchers attempted to control for confounders, but we all know there can always be some that were missed. And we know that if you torture the data enough, it will confess to anything.

We at 21 Debunked think that the relationship between MLDA and later alcohol problems is likely spurious for the following reasons:

  • At least part of the relationship seems to be mediated by self-selective cross-state migration (i.e. budding alcohol abusers moving to states with more lenient laws). But there was no data on state of residence at age 18, only birth state and current state.
  • The relationship was apparently NOT mediated by earlier age of drinking onset, as would be expected if the relationship was truly causal. Also, there was no significant effect on drinking before 18, so we can rule out the often claimed "spillover effect" on younger kids.
  • Drug addiction (especially hard drugs) was affected more strongly than alcohol addiction for whatever reason, the opposite of what would be expected assuming causality.
  • No distinction was made between a drinking age of 18, 19, or 20, which may have a misleading impact on the results.  Though this could bias the results in either direction.
  • The effect on past-year alcohol use disorders was strongest among respondents in their 40s and 50s, and weakest (and statistically insignificant) among those in their 20s, the opposite of what would be expected from a causal relationship. Both drinking age exposed groups start out fairly close, disorders decline at the same rate at first, and divergence does not occur until around age 35.
  • Regressions did not control for state-specific trends, religion, or completely for ethnicity. Whites were treated as a monolithic group (despite wide variation in drinking cultures), and no distinction was made for Native Americans (who tend to have higher alcoholism rates).
  • Unemployment and education were controlled for, but not poverty.
  • The odds ratio for the relationship between MLDA <21 and later alcohol use disorders was an anemic 1.33. In epidemiology, odds ratios and (relative risks) below 2.0 are difficult to interpret and are often due to residual or unmeasured confounding, bias, or even chance. This caveat is especially true for retrospective and non-longitudinal survey studies such as this one. For example, the New England Journal of Medicine would likely consider this association "weak" and thus unfit for publication in most circumstances.
  • And there's always the usual recall bias, as well as good old-fashioned denial. They don't call it a "pink elephant in the room" for nothing.
In other words, the results are preliminary at best. And there's plenty of counter-evidence as well. According to NIAAA data from 1981, courtesy of Mike Males (1986), states with a drinking age of 21 back then actually had higher rates of alcoholism than states with lower drinking ages, and much higher rates of alcohol-related diseases despite both lower teen and adult drinking rates. North Dakota, who nonetheless remained at a constant 21 since the 1930s, is currently the worst state in terms of alcoholism. The worst city is Reno, Nevada, whose state had not seen a drinking age less than 21 for 75 years.

And why does Canada (MLDA 18 or 19 depending on province) not have a higher alcoholism rate than America? Demographically, they probably should! Ditto for most other countries with lower drinking ages, even the notoriously binge-drinking British and Australians? Some may say culture, but Canada's culture is not radically different than ours, and Britain's should, if anything, be more conducive to alcoholism than ours.

Another new study, this one done in Australia (with a legal drinking age of 18), explores the "age at first drink" effect on alcohol dependence from a new angle. Studying numerous twins, they find that there appears to be a gene-environment interaction among those who begin drinking before 15, especially before 13. Such very early drinking, or some environmental factor closely linked to it, appears to activate the bad genes. Though this could simply be a common vulnerability from other differences in environment rather than a truly causal effect of age. Or perhaps the context of drinking matters. The older one starts drinking, the more the environment matters, and the less genes do. But interestingly, and most importantly for the purposes of this discussion, the effect of age at first drink levels off after 18, with no significant difference between those who begin drinking at 18, 19, 20, or even 23. (Funny how this "leveling" effect occurs precisely at the age that corresponds to the MLDA. Coincidence? Hmmm.....)

This jibes well with a Canadian study done in 2000 that found that, while those who begin drinking between 11-14 have the highest risk for later alcohol dependence, even when taking time since first drink into account, there was no significant difference (in the long run) between those who began at 17-18 and those who began at 19 or later.  For the latter group, the onset of dependence was merely delayed.  Again, no conclusive proof of causation, but the authors concluded that prevention programs that succeed in delaying drinking to even 15-16 would likely produce substantial benefits.  This is probably a better idea than trying to make the perfect the enemy of the good, like those who support the 21 drinking age never cease to do.

In other words, we need to see the forest for the trees.  Something we as a society fail to do time and again.

Friday, September 18, 2009

Blast from the Past

One of the fears about lowering the drinking age is that traffic fatalities will rise. Usually, the pro-21 crowd either points to studies of the 1980s, when drinking ages were raised, or the 1970s, when drinking ages were lowered. Having already debunked the studies of the post-1976 period, using studies such as Miron and Tetelbaum (2009), here we look at a period with relatively scant data: 1970-1975, when 30 states lowered the drinking age.

Claim: There was an immediate and persistent increase in (presumably alcohol-related) fatalities among 18-20 year olds when the drinking ages were lowered (generally to 18).

First of all, we don't really know if that statement is even true to begin with, and we probably never will. Only a few decent-quality studies examined the years 1970-1975, the years in which the drinking ages were lowered. The Fatality Analysis Reporting System (FARS), which gives detailed reports about traffic fatalities, was not even created until 1975, and state-level data were not available through that system until 1976. So any conclusions drawn from state-level data for 18-20 year olds before 1976 is questionable at best.  For studies of nonfatal crashes, this caveat applies a fortiori. And any "alcohol-related fatality" data before 1982 is unreliable since FARS did not make this distinction until that year, which is understandable since a state that tested even 50% of fatal crash drivers for alcohol was considered stellar back then. Garbage in, garbage out.

From 1970-1975, any alleged increase in fatalities was imperceptible in the aggregate data. Using data from the National Safety Council, Miron and Tetelbaum (2009) showed that national 15-24 year old fatalities peaked in 1969, then declined sharply until 1975. From 1976-1980, fatalities rose somwhat, and declined from then on. The same was true for 18-20 year olds after 1976, when that group was separated out by FARS and the two groups have been highly correlated since. But the increase in the late 70s also occurred in states like California, which kept their drinking age at 21 throughout, so the 1976-1980 increase was unlikely to be a result of lowering the drinking age a few years prior.

So all state-level data for 18-20 year olds before 1976 must be gleaned from sources other than FARS, and some states had data problems for this period. And here's the grain of truth of it all. It is true that some states that lowered their drinking ages (and some that did not) saw increases in reported 18-20 year old fatalities from 1970-1975. But other states that lowered their drinking ages saw either no significant change or sharp decreases in such deaths in the table below:

StateDrinking Age Change (1970-1975)% Change in 18-20 total auto fatalities per capita (1970-1975)
Lowered, 21 to 19, 1975
Alaska*Lowered, 21 to 19, 1970no data
Arizona*Lowered, 21 to 19, 1972-29%
Arkansas21 (no change)-22%
California21 (no change)-14%
Colorado18 (no change)-10%
Connecticut*Lowered, 21 to 18, 1972+11%
Delaware*Lowered, 21 to 20, 1972+2.3%
DC18 (no change)no data
Florida*Lowered, 21 to 18, 1973-28%
Georgia*Lowered, 21 to 18, 1972-26%
Hawaii*Lowered, 20 to 18, 1972no data
Idaho*Lowered, 20 to 19, 1972-29%
Illinois*Lowered, 21 to 19, 1973-18%
Indiana21 (no change)-19%
Iowa*Lowered, 21 to 19, 1972, then 18, 1973-31%
Kansas18 (no change)-49%
Kentucky21 (no change)-31%
Louisiana18 (no change)-26%
Maine*Lowered, 20 to 18, 1972-14%
Maryland*Lowered, 21 to 18, 1974-8.6%
Massachusetts*Lowered, 21 to 18, 19730%
Michigan*Lowered, 21 to 18, 1972-6.4%
Minnesota*Lowered, 21 to 18, 19730%
Missouri21 (no change)-20%
Mississippi18 (no change)-46%
Montana*Lowered, 21 to 19, 1971, then 18, 1972+19%
North Carolina18 (no change)-10%
North Dakota21 (no change)+5.2%
Nebraska*Lowered, 20 to 19, 1972+7.8%
Nevada21 (no change)-61%
New Hampshire*Lowered, 21 to 18, 1973-59%
New Jersey*Lowered, 21 to 18, 1973+2.9%
New Mexico21 (no change)-14%
New York18 (no change)-9.7%
Ohio18 (no change)-35%
Oklahoma21 (not lowered to 18 until 1976)-14%
Oregon21 (no change)-13%
Pennsylvania21 (no change)-7.1%
Rhode Island*Lowered, 21 to 18, 1972+67%
South Carolina18 (no change)-25%
South Dakota*Lowered, 19 to 18, 1972-31%
Tennessee*Lowered, 21 to 18, 1971-1.6%
Texas*Lowered, 21 to 18, 1973+2.0%
Utah21 (no change)-49%
Vermont*Lowered, 21 to 18, 1971+161%
Virginia*Lowered, 21 to 18, 1974-17%
Washington21 (no change)-7.1%
Wisconsin**18 (no change for on-premise beer)**-7.1%
West Virginia18 (no change for beer)+1.9%
Wyoming*Lowered, 21 to 19, 1973+1.0%
(Taken from Cook and Tauchen (1984), Appendix A. Calculations ours. All data involves purchase age for beer unless otherwise noted. Dates taken from Wikipedia)

Thus, the state-level data are completely patternless, at least in terms of drinking age. Clearly, other factors were involved, such as gas prices (now known to have an effect), the economy, or even the weather. Only a handful of states (mostly with relatively small populations and hence much volatility in the numbers) in the table show significant increases, including one (North Dakota) that kept a constant 21 MLDA since the 1930s. The rest either saw sharp decreases or no significant change. This was in spite of the fact that, nationwide, the average driver in 1975 traveled more vehicle miles than in 1970. And before the advent of FARS, any increases are not clear as to whether they reflect true fatality increases or simply changes in how fatal crashes were reported. Nor does this table tell us whether those increases were contemporaneous with the age-lowering (done mostly in 1972-1973) since only two years, 1970 and 1975, were compared due to data availability. For example, Vermont's rather large increase, apparently, was not contemporaneous (See Douglass and Filkins, 1974).

A quick, albeit imperfect, way to estimate the effect of a policy change ceteris paribus is a method called "difference-in-differences," or DD for short. Here, we do a DD analysis comparing change vs. no change states:

Median difference, "change" states (1975 vs. 1970): -6.8%
Median difference, "no-change" states: -16.5%
Net difference-in-differences: +9.75%

This implies that, while both groups declined overall, the no-change states declined at a significantly faster rate than the states that lowered their drinking ages. And the latter group can be said to have more deaths at first glance. However, there are two radical outliers (VT and RI) that dramatically skew the results. Furthermore, Delaware is the only state that lowered the age from 21 to 20 and no further, and Wisconsin would better be included with the no-change states since 18 year olds were allowed to drink beer in bars both before and after. Thus, we omit the two outliers and Delaware entirely, and instead place WI with the no-change in our adjusted DD analysis:

Adjusted median difference, "change" states: -11.3%
Adjusted median difference, "no-change" states: -14.0%
Net difference-in-differences: +2.7%

Wow, that really makes a difference in the results. The net DD drops from nearly +10% to less than +3%. The latter "effect size" is small enough to be due to chance alone. Indeed, we also observe in the table that several of the states with significant increases are also states with some of the smallest 18-20 year old populations. Such states are prone to spurious shocks due to the volatility of smaller numbers of fatalities. Thus, we see that when we eliminate all the states with populations less than or equal to that of Montana, along with making the aforementioned adjustments, the drinking age effect disappears entirely:

Adjusted median difference, "change" states: -14.0%
Adjusted median difference, "no change" states: -14.0%
Net difference-in-differences: 0%

Regardless of what happened (or didn't happen) in the 1970s, it is essentially irrelevant today. Back then, drinking ages were lowered against a backdrop of falling real alcohol prices, higher adult per capita alcohol consumption than today, permissive and toothless DUI laws, social acceptability of drunk driving, no seat belt laws, ignorance about the risks of alcohol, and a generally cavalier attitude toward safety. The term "air bag" meant a person who talked too much. The term "designated driver" was not even in our vocabulary until the 1980s. Drunk driving was not just tolerated back then, it was expected of you if you were the least drunk person in the group (to drive everyone else home). Needless to say, things are very different today. So it's comparing apples and oranges. And any fear relating to the 1970s is therefore academic. Consider it debunked.

Claim:  There was a major increase in high school drinking (and related problems) when the drinking age was lowered, as 18 year olds bought for their younger friends.

Again, correlation does not equal causation.  It was true that in the 1970s, teen drinking increased, but that was a national trend that occurred in essentially every state, including those like California that kept the drinking age at 21.  In fact, the secular trend predated the 1970s by many decades, and ironically enough began during Prohibition in the 1920s.  It lasted until about 1979, then the trend reversed and teen drinking declined through the 1980s until the early 1990s.  And the downward trend predated the raising of the drinking age, and again occurred in essentially every state.

The average age at first drink did decline nationwide, but that began in 1965 (or earlier), and continued to decline long after the drinking age was raised in the 1980s. And California, who had a 21 drinking age since 1933, saw the same trend overall as the rest of the country. So clearly other factors are at work, and the trends cannot be traced to changes in the drinking age.

Part of the increase in teen drinking could be that parents stuck their heads in the sand about alcohol, being relieved that "at least my kid isn't smoking pot."  Or it could have resulted from a moral panic and a consequent deviancy amplification spiral.  Or perhaps a bit of both, with the former preceding the latter.

Interestingly, a 1977 study found that high school seniors in states with a drinking age of 18 actually drank less and had fewer alcohol-related problems than those in states with a drinking age of 20 or 21.  Why this is is not entirely clear, but the researchers hypothesize that "forbidden fruit" may very well entice those in the more restrictive states to drink.  Or perhaps those seniors that are still 17 are more likely to wait until 18 to be legal since this is more realistic than waiting until 20 or 21.

Again, much of the fears from the 1970s are now academic, and are unlikely to be a problem if the drinking age was lowered today.  The notion of teenagers having "liquid lunches" in high school is no longer socially acceptable--it is now considered a sign of a drinking problem.  Those who are caught bringing booze to school are dealt with much more harshly than they were back then, campuses are often closed, and students are essentially defanged and declawed.  And today's tough enforcement requires IDs to be shown when purchasing alcohol, reducing the chances of a 15-17 year old "passing" for 18.  About the last remaining fear is high school keggers (which still occur even with a 21 drinking age), but any possible increase in these parties can (by definition) be prevented by keeping the purchase age at 21 (or 20) for bulk quantities like kegs and cases while lowering it to 18 for everything else. 

One thing, however, is for sure:  teenagers will get their hands on booze one way or another, and whether the drinking age is 18 or 21 is of little consequence to this fact.  Where there's a will, there's a way.  And where there's a swill, there's a sway.  So consider this one debunked as well.


Thursday, September 17, 2009

Daredevil Behavior and the Teenage Brain

Teenagers are often assumed to be risk-takers who engage in dangerous and idiotic activities. And that is often true. But compared to American adults, they are really not that bad.

It is often assumed that it is due to their "underdeveloped brains," which apparently continue to develop until at least age 25. This factoid is heard so often that it is taken as gospel. Indeed, numerous studies have revealed changes in the adolescent and young adult brain. So one must lead to the other, right?

But what if the supposed causation is not just inaccurate, but in fact is 100% wrong? Apparently, a new study of brain imaging suggests just that. They found that the more mature and "adult" the white matter of teen brains was, the more risk-taking behavior reported, the opposite of what was expected. Of course, the direction of causality is uncertain, but doesn't this blow a hole in the conventional wisdom?

Another study finds that, among 10-16 year olds, shortsightedness is not caused by impulsivity (lack of self-control), but rather by sensation-seeking. While 10-16 year olds did tend to think about the future less than adults do, and thus prefer immediate rewards to delayed ones, there was little change in shortsightedness after 16 (the study looked at 10-30 year olds). This is interesting since the parts of the brain that are related to sensation do not continue maturing after 16, but the parts responsible for self-control do. Still, shortsightedness changes little between the ages of 16 and 30.

The results of another study imply that, at least in terms of resistance to peer influences, 18 year olds are essentially just as competent as 23-30 year olds.  This echoes older studies that found that results on tests that measure competence to stand trial seem to level off after age 16, similar to the way IQ typically does.

Another study found that the likely explanation of the relationship between age at first drink and subsequent drinking problems has to do with the quality of the parent-child relationship. In other words, the better the quality, the later drinking begins and the fewer drinking problems. Age at first drink may simply be a marker for later problems or lack thereof, since it appears to be a marker for the relationship quality. Still another study finds that child maltreatment is independently linked to adolescent "binge" drinking (5+ drinks/occasion), as was the pink elephant in the room (parental alcoholism).

What does all this have to do with the 21 drinking age? Plenty. Arguments supporting a drinking age higher than the age of majority do not appear to hold water upon closer examination.