THE MOLECULE OF MOREtranslate our inner world of ideas into action, the way we impose our
will upon the world. When there is not enough dopamine in this circuit,
people become stiff and shaky, and they move slowly. The treatment is
to prescribe drugs that boost dopamine.
Most people who take these drugs do just fine, but about one in
six patients gets into trouble with high-risk, pleasure-seeking behavior.
Pathological gambling, hypersexuality, and compulsive shopping are
the most common ways the excessive dopamine stimulation is seen. To
explore this risk, British researchers gave a drug called L-dopa to fifteen
healthy volunteers. L-dopa is made into dopamine inside the brain,
and can be used to treat Parkinson’s disease. They gave another fifteen
volunteers a placebo. Nobody knew who got the drug and who got the
fake pill.
After they took the pills, the volunteers were given the opportu-
nity to gamble. The researchers found that the participants who took
the dopamine-boosting pill placed larger and riskier bets than those
who took the placebo. The effect was more pronounced in men than
in women. The researchers periodically asked the participants to rate
how happy they were. There was no difference between the two groups.
The enhanced dopamine circuit boosted impulsive behavior, but not
satisfaction—it boosted the wanting, but not the liking.
When the scientists used powerful magnetic fields to look inside their
participants’ brains, they found yet another effect: the more active the
dopamine cells were, the more money the volunteers expected to win.
It’s not uncommon for people to deceive themselves in this way.
There are few things we encounter in daily life that are more unlikely
than winning the lottery. A person is more likely to have identical qua-
druplets, or be killed by a vending machine tipping over. It’s over a
hundred times more likely that a person will be struck by lightning than
win the lottery. Yet millions of people buy tickets. “Someone has to
win,” they say. A more sophisticated dopamine enthusiast expressed his
devotion to the lottery in this way: “It’s hope for a dollar.”
Expecting to win the lottery may be irrational, but far more severe
distortions of judgment can occur when people take dopamine-boosting
medicines every day: