It’s a sensation many beer connoisseurs can relate to: that feeling that, over time, as you sample increasingly stronger, hoppier beers, nothing is enough to quench that craving for a blast of bitter, hoppy bliss. Over at Popular Science, “BeerSci” blogger Martha Harbison described the process in the following way:
Start off drinking beers with lower IBUs (International Bitterness Units, one measure of how bitter a beer is), be them ambers, lagers, brown ales, or stouts. Next, try a pale ale. Then try many pale ales. Then discover the IPA--and with it, become obsessed with hop varietals such as Simcoe (pney aroma) and Amarillo (fruity aroma). Be happy with that for a while. Maybe try a double IPA (twice the malt, twice the hops as a regular IPA), which may or may not be successful, depending on whose you drink. Begin to love being punched in the face with a fist of hops. Become obsessed with IBU ratings. Buy the hoppiest beers one can find, even if they don’t actually taste all that good. Despair.
But is that an addiction? The process sounds oddly similar to the way guidance counselors in high school warn of marijuana as a gateway drug, leading smokers down the inevitable path to harder drugs. But Harbison says it’s not. Unlike caffeine or tobacco, hops can be trimmed from a diet without any symptoms of withdrawal. Plus, humulones, the compound in hops that gives beer its bitterness, don’t affect the brain the same way as recognized, addictive compounds.
Harbison says that “some scientists suggest that the culprit is sensory adaptation and habituation. Adaptation occurs when your perception of taste or smell dissipates over the course of exposure to the sensation. Adaptation happens quickly, usually over a few minutes, and reverts to the normal sensitivity within an hour or so."
Habituation, on the other hand, means that for a long time after the initial exposure, sensitivity to the sensation remains diminished. Research indicates, for example, that capsaicin [the compound that makes chiles hot] exposure has both an adaptation element (the heat in that salsa will only be bad for about 15 minutes), and a habituation element (for about a week afterward, that salsa will remain less "hot" to the test subject, which scientists suspect is why some people can tolerate much hotter foods than others).
Perhaps it’s the association of hoppiness with stronger alcohol content in beers that drives the sense of addiction. Beer lovers not only get used to drinking more bitter beers, they often get used to drinking ones with higher alcohol content. The hops are the bell that make Pavlov’s dogs water at the mouth: only this time it’s for booze.