Last Friday around lunch break, sweating profusely on the way back to lab, I was suddenly struck by an irresistible urge to chug a cold fizzy beer. Crisp! Grassy! Bubbly! The punchline? Due to a genetic inability to metabolize alcohol, I stick to the extra lights (I know, I know). To me, beer is intoxicating even without apparent alcohol intoxication.
And the culprit that triggers this lust for a sip –or keg- of beer? A new study points to dopamine, a neurotransmitter involved in reward prediction and motivation. In the early stages of drug use, cocaine, meth and amphetamines all trigger a dopamine rush in the brain’s reward system, which induces a sense of high-flying pleasure, power and jazzed-up ENERGY. But the “feel good” molecule has a dangerous side: it also encodes for triggers that lead to the expectation for reward. Hence the theory goes, with each increased pint of beer, the sight, smell and taste of it starts becoming sufficient to trigger a dopamine rush, signalling to us that reward is coming long before the beverage touches our lips. One camp of thought stipulates that these beer-related cues may eventually trigger feelings of wanting and craving, leading to alcoholism in the vulnerable.
Is it possible that the taste of beer, instead of the alcohol it carries, can act as a cue and kick-start the cycle of use, reuse and abuse?
Brandon G Oberlin et al (2013). Beer Flavor Provokes Striatal Dopamine Release in Male Drinkers: Mediation by Family History of Alcoholism. Neuropsychopharmacology 38: 1617-1624
To answer this question, researchers recruited 49 male beer lovers, ranging from the occasional social drinker to the potentially problematic binger. The volunteers were separated into three groups: those with or without a family history of alcoholism, and those who don’t know. Researchers then teased their taste buds (and brain) with a tiny squirt of either their favourite beer or Gatorade – an amount way too small to cause intoxication – while monitoring their brains’ responses to the flavours with Positron Emission Topography (PET) and the radioactive tracer RAC. RAC competes with dopamine released in the brain for binding spots on the dopamine receptor – hence low RAC binding tells us that there’s MORE dopamine around, and vice-versa.
The findings were remarkable straightforward: a taste of beer, but not Gatorade, elicited a desire to drink more beer in all volunteers, regardless of family history. Pooling all of the volunteer’s data together, RAC binding dropped significantly in the right ventral striatum during beer tasting compared to Gatorade tasting, indicating more dopamine release. Unfortunately, the magnitude of dopamine release was NOT related to subjective feelings of wanting to drink beer, how much beer the volunteers drank previously or how much more they preferred beer to Gatorade.
However, as you can see below, the taste of beer did induce larger dopamine release in those with a family history of alcoholism (black bar) compared to those who didn’t (white) or those who didn’t know (grey). The authors hence concluded that the taste of beer (“intraoral sensory properties”, gotta love jargon sometimes), in cahoots with its alcohol properties, might together induce dopamine responses that in turn promote and maintain booze-craving and seeking behaviour.
My first non-scientific reaction: has anyone ever become an alcoholic from drinking light beers? How much, if any, does the taste of alcohol contribute to addiction, even in those with bad/vulnerable genetics? Based on this study, I’d say very little. If you look closely at the graph above, the effect size is incredibly small. So small that, when researchers looked at each group separately (not pooled like described above), only people with a history of alcoholism (Family History Positive) showed significant dopamine release after tasting beer.
Next, even though FHP volunteers had larger dopamine release in response to beer, it did not correlate with how much pleasure they felt nor how much they wanted beer afterwards; the neurobiological response did not translate to behaviour. The magnitude of dopamine response also didn’t correlate with how much the volunteers drank on average. Together, the results show that dopamine release in response to a taste of beer CANNOT predict a person’s potential of alcoholism, regardless of family history.
The one solid conclusion from the study is that beer-related cues make you want more beer if you already like beer. (Do we really need science to tell us that?) In some people this is paralleled in time to dopamine release – which we already know from previous studies that used pictures of alcoholic beverages. In fact, the same dopamine response is seen for most rewarding things, such as food and drugs (and maybe even Gatorade!).
Maybe someone should study whether reading about beer-related studies triggers dopamine release in the beer-lovers’ brains.
Oberlin BG, Dzemidzic M, Tran SM, Soeurt CM, Albrecht DS, Yoder KK, & Kareken DA (2013). Beer flavor provokes striatal dopamine release in male drinkers: mediation by family history of alcoholism. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology, 38 (9), 1617-24 PMID: 23588036