Exposure to cocaine during pregnancy leads to poor impulsive control in male monkeys later in life, a new American study aimed at furthering the understanding of the effects of drug abuse on humans has found.

The research by the Wake Forest University School of Medicine was presented at the annual Society for Neuroscience meeting in Chicago.

Lindsey Hamilton, lead researcher and a graduate student, said: "This is the first time that so many different measures of impulsivity, which is considered a risk factor for drug abuse, have been looked at in the same group of animals.

"We're looking for ways to predict which individuals are going to take drugs during their lives. It was very surprising to see that, even more than a decade after the prenatal cocaine exposure, the monkeys ended up being more impulsive and possibly more susceptible to drug use. It was particularly interesting, however, that this effect was only seen in the males. Something is either protecting the females from the effects of the cocaine exposure in the womb or making the males more susceptible to the lasting effects."

The researchers compared the impulse control of male and female adult monkeys exposed to cocaine while in the womb 15 years ago, to come up with their findings.

In one of the tests, the monkeys were given a choice between pushing a lever that let out a single banana pellet instantly or a lever that gave them several banana pellets, but for which they had had to wait for nearly five minutes.