Debate Brews Over Caffeine Addiction -- Study Also Confirms Caffeine Improves Alertness And Energy

At doses of one to three cups of coffee a day, a fairly typical consumption for Americans, caffeine has no affect on the area of the brain involved with addiction, dependence and reward, claims Astrid Nehlig, Ph.D., research director at the Strasbourg, France, laboratory of INSERM, the French National Health and Medical Research Institute.

Nehlig recently completed a study with laboratory animals, which confirmed that caffeine consumed in moderation contributes to increased alertness and energy but does not bring about dependence at those levels. Caffeine appears to act differently from amphetamines, cocaine, morphine or nicotine, Nehlig says. Even at low doses, these drugs trigger functional activity in the shell of the nucleus accumbens, the part of the brain responsible for addiction, she says. It would take the equivalent of about seven or more cups of caffeinated coffee consumed in rapid succession to begin to activate this portion of the brain. Even then, she adds, "activation of the circuitry of addiction and reward occurs only at high doses of caffeine, which probably induce already adverse effects." These effects can include anxiety, nervousness and depression, Nehlig says.

Acknowledging that there is a "big debate" among researchers about whether caffeine is addictive, Nehlig noted "one epidemiological study reported dependence over a wide dose range," from as little as one or two cups per day to as much as 25 cups.