Drunk Monkey, Sober Monkey

Brains of alcoholic monkeys contain clues about the biology of addiction.

Posted Sep 30, 2012

Picture this: you are on an expansive white sand beach, drowsing in the sun, listening to the surf and the calls of seabirds. You sip your drink, set it aside, and tip your beach chair back a bit further. You hear a faint rustling near your towel, and with a sigh, you crack an eye and prop yourself up to have a look—only to see the tail-end of a tawny monkey making a beeline to the nearest palm tree, screeching happily—with your frozen margarita sloshing precariously in the grip of her tiny fist.

St. Kitts vervet monkeys snag alcoholic drinks on the beach

The situation in St. Kitts—individual differences in alcohol preferences occurring “naturally” in a population—has provided a unique opportunity for researchers to examine the biological substrates of susceptibility to alcohol addictionIn a particularly fascinating example of such research, scientists selected monkeys based on individual differences in observed alcohol consumption over a period of two years in St. Kitts. These researchers then examined the dopamine system in the brains of these animals by measuring the distribution and density of a transporter protein called the Dopamine Transporter (DAT);  specifically, they compared levels of this protein in alcohol-preferring versus alcohol-abstaining monkeys.

Similar alterations in Dopamine Transporter have been observed in human alcoholism, and interestingly, Major Depressive Disorder is also associated with higher availability of Dopamine Transporter. Perhaps this individual difference in the brain dopamine’s system can help explain why many individuals who suffer from depression appear to self-medicate with alcohol, and provide a biological target for pharmacological and cognitive therapy in these harmful disorders.

Mash et al., 1996. Altered dopamine transporter densities in alcohol-preferring vervet monkeys NeuroReport, 7 (1996), pp. 457–462