Altered Perception Of Reward In Human Cocaine Addiction

A new study identifies a possible neurological mechanism to explain cocaine addiction's power to interfere with rational decision making. Anecdotally, I don't hear stories about heroin addicts giving their car to the dopeman, the way you do about cocaine addicts.

...in one study, subjects were given a monetary reward for their performance on an attention task. Subjects were given one of three amounts (no money, one cent, or 45 cents) for each correct response, up to a total reward of $50 for their performance. The researchers also asked the subjects how much they valued different amounts of monetary reward, ranging from $10 to $1000.

More than half of the cocaine abusers rated $10 as equally valuable as $1000, "demonstrating a reduced subjective sensitivity to relative monetary reward," Goldstein said.

"Such a 'flattened' sensitivity to gradients in reward may play a role in the inability of drug-addicted individuals to use internal cues and feedback from the environment to inhibit inappropriate behavior, and may also predispose these individuals to disadvantageous decisions -- for example, trading a car for a couple of cocaine hits. Without a relative context, drug use and its intense effects -- craving, anticipation, and high -- could become all the more overpowering," she said.