August 19, 2011
Two friends with similar backgrounds both drink heavily while in their 20s, but one eventually cuts down and moves on, while the others drinking progresses into full-blown alcoholism. While science is still unable to distinguish between these two individuals before they start drinking, recent advances in addiction research show promise in explaining why some people can engage in potentially addictive activities in moderation while others cannot.
Most of us can relate to the experience of wanting to do some pleasurable thing we know is bad for us — mentally struggling for a few moments over what to do, and then giving into the urge. From a neurological perspective, this is our cortex (the part of our brain that makes complex decisions) losing an argument with our reward system (a more primitive set of brain structures). Over hundreds of thousands of years, evolution has fine-tuned the connection between these systems to create the right balance between drive and restraint. Scientists believe that addiction may be the result of the connections between these areas of our brain becoming imbalanced.
Just as we differ from one another in physical characteristics, we also differ in neurological ones. For example, John and David both have eyes, but John’s are brown and David’s are blue. Similarly, both John and David have short-term memory, but John may recall information more rapidly than David. When neurological characteristics such as these are associated with a disorder and are determined by our genes, neurobiologists call them “endophenotypes.”