One of the characteristics of anorexia, says researcher and clinician Daniel LeGrange, is not just starvation; rather, he says, it is starvation in the midst of plenty. While one theory is that anorexia may have evolved as an adaptation to allow humans to better withstand famine, most modern cases of anorexia occur where food is abundant. In that sense, perhaps anorexia can be understood as self-administered starvation.
Which is where a recent study on cocaine addiction comes in.
A recent study from the University of California, San Francisco found that self-administered cocaine had different effects on dopamine receptors than a passive infusion of the drug.
Says a press release:
...cocaine-associated changes were due to an associative process and not just to the pharmacological effects of the drug. "We suggest that neuroadaptations induced specifically by drug self-administration may form a powerful 'memory' that can be activated by drug-associated cues," explains coauthor Dr. Billy T. Chen.
How self-administration of a drug but not a natural reward can elicit enduring changes within the brain remains a mystery. "Future studies are required to identify the exact mechanisms through which drugs of abuse alter neural circuitry that is normally accessed by naturally reinforcing events but is usurped by cocaine to persistently cement these synaptic adaptations, perhaps ultimately leading to pathological drug-seeking behavior," concludes Dr. Bonci.
While anorexia is not cocaine addiction, the illness does involve differences in dopamine levels and receptors in the brain. Perhaps part of what cements anorexia (besides the starvation itself) is the self-seeking behavior. The "benefits" of starvation to the sufferer are reinforced each time he or she skips a meal, binges, purges, and overexercises.
From an evolutionary standpoint, the survival of the human species means that people will need to begin eating after a famine has passed. The ability to withstand starvation may have descended from this. But anorexia nervosa may cement itself into a life-threatening illness when a person begins to starve while food is abundant.