by Tara Deliberto
Believe it or not, glucose levels can have direct effects on your ability to control yourself. Studies done by Gailliot et al. show that slightly depleted glucose levels lead to more errors on tasks and less persistence, indicating decreased self-control. Because our natural instincts are so strong, the act of self-control over these impulses are thought to be the most mentally expensive cognitive ability.
Although we are less able to process glucose at night, some people have trouble controlling their glucose regardless of the time of day. Considering depleted glucose leads to a lack of self-control, perhaps it isn't surprising to learn that evidence suggests people who engage in criminal behavior have problems processing glucose. Along with criminal behavior, it makes sense to me that people with addictions may have similar physiological deficits.
Interestingly, there is evidence to suggest that people can actually be physiologically addicted to sugar. While one can develop a psychological addiction to almost anything, physiological addiction is indicated by the presence of a withdrawal process after the substance ceases to be used. Because the drug naloxone will induce withdrawal only if a person has a physiological addition, administering this drug tells us whether or not an addiction is present. Fascinatingly, it has been shown that giving this drug to rats consuming large quantities of glucose in fact causes withdrawal, indicating that physiological addition to sugar is possible(Colantioini et al., 2002).
Are you thinking what I'm thinking?
While it may be a stretch... perhaps over time people are negatively reinforced (this is when an aversive stimulus is taken away, not when a punishment is introduced)after eating sugar and not engaging in a problematic behaviors. They could even be positively reinforced by being able to complete a task successfully (etc) after consuming glucose. If addiction could be mediated by the inefficient processing of glucose, could increasing sugar intake work as a self-medicating impulse control process?
Although sugar consumption may act directly on the problematic system, other behaviors are most likely a result of the lack of regulation without the direct self-medicating component. For example, while drinking excessively could be used to self-medicate emotional problems, the immediate effect of drinking 15 beers is depleted glucose, not increased glucose. Although the impulsive act of drinking to excess in the first place could be partially due to a lack of glucose (with alcohol exacerbating lack of control), alcohol consumption doesn't act to solve the potential underlying problem of glucose being processed ineffciently in the way the sugar consumption may.
P.S. This is an edit from 2/15/12 - I just read a review paper by David Benton in Clinical Nutrition, 29, that suggests sucrose is not physiologically addicting in the same way substances are. Interesting.