According to an article published in the Harvard Mental Health Letter in January, new research on the brain shows addiction to be a matter of memories with recovery a painstaking process in which the influence of powerful memories are diminished. In the brain, addictive drugs target a circuit in the center region called the nucleus accumbens, commonly referred to as the reward circuit because its job is to stimulate action by registering pleasure or satisfaction when experiencing something useful for survival or reproduction.

Reward experiences cause the release of the neurotransmitter dopamine which tells the brain to "do it again." The brain then records what "it" is by making connections between lasting implicit memory and emotion in the amygdale and hippocampus. Implicit memory is characterized by a lack of conscious awareness in the act of remembering. The CEO of the brain, the frontal cortex, seat of higher functioning that separates us from other living species, uses this information to asses the value of the reward, compare it with other rewards and make plans. Dopamine activity increases not just when a reward is experienced but also when it anticipates (even at an unconscious level) the possibility of reward.

Surprisingly, these changes alone do not make addiction inevitable. Quitting, at least temporarily may, comparatively speaking, be the easy part. From a biology standpoint, what makes permanent recovery so difficult is drug-induced change that creates lasting memories, memories the addict knows too well will result in a pleasure experience.

Environmental cues that trigger reminders (even those out of conscious awareness) of the drug prompt the release of dopamine and the siren call to "do it again." Economic and cultural conditions can also affect the likelihood that implicit memories will take command.

This kind of learning is called behavioral conditioning. It works because addictive drugs hijack the brain and a side effect is that the frontal cortex becomes less effective in its ability to incorporate information needed to make decisions and judge consequences of actions, thus reducing self-control. Without other strong interests, sources of satisfaction and ways to solve problems, the probability of relapse increases exponentially.

Today researchers are beginning to explore the differences and similarities between drug addiction and other consuming habits that may only differ in degree. "Addiction" to television, shopping, computer games and even biologically natural rewards like food and six, are suspected of sharing common learning and memory pathways.