Here's an NYT story about rising concern over drinks that are basically energy drinks mixed with alcohol. Although I'm not a regular drinker, I still remember one of the most enjoyable drinks I've ever had was an Irish coffee. I'd never heard of it before, but a bunch of us in Barcelona were out for a long night, so the idea of loosening up with booze while keeping my energy going with coffee was an easy sell. I don't recall anything like what the article says about the effects of "alcopop" drinks. Plus, when I went dancing twice a week in Barcelona they gave you a ticket for one drink when you paid to enter, and I would always get a Cuba libre, again never experiencing anything like the alcopop effects.
Clearly there is something else about drinks like Four Loko, Joose, Sparks, Tilt, etc., since just caffeine and alcohol won't produce the effects. Whenever there's junk food with particularly destructive effects, it will always be due to one of two ingredients -- empty carbs (like sugar) or cheap vegetable oils (like soybean). Obviously in this case it must be sugar. I do remember getting weird while drinking a Monster energy drink every morning for the 2007-08 school year, or a store-bought Frappuccino almost every day in the years before that. These are both full of sugar.
After some googling, yep, that's it. One can of alcopop has anywhere from 30 to 190 grams of carbs, all digestible, most or all of it sugars. For comparison, a candy bar usually has around 30 grams. A mixed drink with Coke only has so much of it, not a whole can, so you're probably only getting 10 grams. A shot of Baileys, which also has sweeteners, still only has 11 grams. And that Irish coffee I drank apparently had 1 tsp or merely 5 grams of brown sugar -- I couldn't even taste it and only learned this from looking up the recipe.
You might think that the alcopops are being targeted because they're mainly consumed by younger and lower-status people, but then so is rum and Coke, which doesn't cause the same worries. Explanations based on pop cynicism, being so knee-jerk, are rarely right. Here it seems like there is something different about the effects of alcopop drinks, and it's almost surely due to the pounds of sugar they have.
I think this also underlies what many view as a qualitatively different drinking culture among young people over the past 20 or so years -- the antics of "binge drinking" on campuses in particular. It's not as if getting blindingly drunk is new -- in fact, old. And it used to be more prevalent and tolerated. But with the wussification of society in the past roughly 20 years, young people have switched their drinking culture to one that relies so heavily on saccharine drinks that happen to have some alcohol hidden in there somewhere. Everything involving hard liquor now is ___ and Coke, ___ and one of a cornucopia of fruit juices, or god help us even ___ and Kool-Aid.
My impression of the earlier drinking culture of young people is that it wasn't so dependent on sugary drinks, except in the unusual case of someone spiking the punch bowl at a school dance. At least in TV and movies, you see them with bottles and shot glasses and flasks (and beer of course), not rows of soda and fruit juice jugs. So, while they were getting plastered, they were not also getting the unique combination of frenzy and irritability that comes from a sugar rush (and eventual sugar crash). Merely adding caffeine won't yield those effects either; it just puts some pep in your step. That's probably why young heavy drinkers from circa 1975 looked more like jovial party animals, while those of today come off as neurotic trainwrecks.