Nicotine as a performance enhancer? Research results are spotty

Many researchers commonly name cognitive enhancement as one of the reasons smokers continue to smoke. However, the jury is still out on whether nicotine really does enhance cognitive performance.

'It does enhance some aspects of performance, but not across the board and not from study to study in a very reliable way. It's not a very robust performance-enhancing drug,' says Stephen Heishman, PhD, a researcher at the National Institute on Drug Abuse Intramural Research Program in Baltimore.

In fact, a lot of the early studies on nicotine and cognitive enhancement were actually measuring the alleviation of nicotine withdrawal, says Heishman. Researchers would take smokers who hadn't had a cigarette in 10 to 12 hours, measure their cognitive performance, then give them a cigarette and measure their performance again.

The enhanced performance they saw was simply the reversal of the cognitive deficits that occur the first few weeks of nicotine withdrawal, says Heishman, who has published several reviews of the literature in this area (Addiction, Vol. 93, p. 317-320; Experimental Clinical Psychopharmacology, Vol. 2, p. 345-395).

Better controlled studies, examining the effect of nicotine on nonsmokers, find that while nicotine may improve performance on some types of cognitive tasks-in particular finger-tapping rate, sustained attention and some aspects of memory-the findings are spotty and the improvements relatively weak. In fact, no one to date has examined whether nicotine can enhance performance in a significant way on real-world tasks, says Heishman.

But Southern Illinois University professor of psychology David Gilbert, PhD, believes the link between nicotine and cognitive performance is stronger than Heishman's research suggests. In his book 'Smoking: Individual Differences, Psychopathology and Emotion' (Taylor & Francis, 1995), Gilbert theorizes that most people who smoke are in some ways self-medicating mood problems and deficits in attention or other aspects of cognition. The small effects on cognition seen in nonsmokers may simply indicate that most nonsmokers are at their maximum performance already, he says.

Gilbert's preliminary results suggest that even a month after people stop smoking, they haven't recovered from nicotine withdrawal. Indeed, in two separate studies-one in a group of 54 men (Personality and Individual Differences, Vol. 25, p. 399-423) and one in a group of 83 women (submitted for publication)-the depressed brain wave patterns, mood and cortisol levels often seen in people who quit smoking failed to recover 31 days after participants stopped smoking.

The lack of recovery could have several explanations, says Gilbert. It could mean that recovery has a much slower trajectory, or that nicotine has a more permanent physiological effect, than previously thought. Or people may be returning to the level of function that they had before they started smoking. Although Gilbert concedes that more experiments are needed to prove the latter theory, it's the one he thinks will win out in the end.

Heishman says he doubts that adolescents start smoking to self-medicate cognitive deficits. 'They might use it as stimulant to stay awake,' he says. 'But they could use other things like caffeine.'

'Obviously it is a reason for people to relapse once addicted,' says Heishman. 'They stop and they experience clouded thinking and difficulty attending and maintaining concentration.'

-B. Azar



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