DRUGSAlan Leshner, the former director of the National Institute on Drug
Abuse, said that drugs “hijack” the desire circuit. They stimulate it far
more intensely than natural rewards like food or sex, which affect the
same brain-motivation system. That’s why food and sex addictions have
so much in common with addiction to drugs. Brain circuits that evolved
for the crucial purpose of keeping us alive are taken over by an addic-
tive chemical, and repurposed to enslave the addict that gets caught in
its net.
Drug abuse is like cancer: it starts small but can quickly take over
every aspect of a user’s life. An alcoholic may start out as a moderate
drinker. As he moves step by step from, say, a few beers on the weekend
to a liter of vodka every day, other aspects of his life get swallowed up.
At first he stops going to his son’s baseball games so he can stay home
and drink. After a while the parent–teacher conferences go, then all
family activities, and last of all work, since that supplies money to buy
the alcohol. But in the end even work goes. Like a tumor, the addic-
tion has spread, and the alcoholic’s entire life becomes focused exclu-
sively on drinking. Was he making rational choices? From the outside it
doesn’t look like it.
But from the inside, where we see dopamine in action, it makes
perfect sense.
The dopamine system evolved to motivate us to survive and repro-
duce. For most people there is nothing more important than staying
alive and keeping their children safe. These are the activities that pro-
duce the largest dopamine surges. In a very literal way, large dopamine
surges signal the need to react to life-and-death situations. Take shelter.
Find food. Protect your children. These are tasks that hit the dopamine sys-
tem hard. What could be more important?
To an addict, drugs are more important. At least that’s the way it
feels. That guided-missile dopamine blast overwhelms everything else.
If making decisions is like weighing options on a balance, an addictive
drug is an elephant sitting down on one side of the scale. Nothing else
can compete.
An addict chooses drugs over work, family, everything. You think
he’s making irrational choices but his brain is telling him that his choices