It is quite well known that consuming cocaine or being exposed to cocaine could be bad for health. Well now a study from Wake Forest University School of Medicine claims that adult male monkeys exposed to cocaine while in the womb have bad impulse control and may be more susceptible to drug abuse as compared to female monkeys, even a decade or more following the exposure. The findings could result in a better understanding of human drug abuse.
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. This was mentioned by lead investigator and a graduate student working in the laboratory of Michael Nader, Ph.D., a professor of physiology and pharmacology.
Hamilton added, “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 experts compared adult monkeys prenatally exposed to cocaine more than 15 years ago, to monkeys who were brought up under identical situations, but not exposed to cocaine during gestation. To decide if the animals fluctuate in impulse control, they conducted four exams. For one of the tests, the experts gave the animals the option between pushing a lever that delivered a single banana pellet reward instantly or a lever that delivered several banana pellets, but the animals had to wait up to five minutes before the prize was given.
Hamilton remarked, “That’s where we saw very large differences between the groups. The males who were exposed to cocaine in-utero had no patience or impulse control whatsoever.”
It was seen that those monkeys were not eager to linger around for a bigger food prize and favored the instantly available, although much smaller, incentive, demonstrating they were more impulsive as compared to the adult male monkeys who had never been exposed to cocaine. There was, nevertheless, no apparent distinction in the inclination of female monkeys prenatally exposed to cocaine and those never exposed to the drug.
After all of the impulsivity tests were taken, the experts graded every monkey from least to most impulsive and evaluated their average impulsivity score across the four tests. They discovered that male, but not female, monkeys prenatally exposed to cocaine were more impulsive by and large as opposed to control monkeys who weren’t exposed.
Hamilton mentioned, “The more challenging the test, the more obvious the difference between the groups was. The fact that we are seeing differences at all is particularly striking because this is 15 years after the monkeys were exposed in the womb to cocaine. Fifteen years is the equivalent of middle age for monkeys. The fact that fairly large differences are still turning up is fascinating.”
Hamilton defined the results more by clarifying that dopamine is a chemical in the brain that has been linked to drug abuse. When dopamine is released, it is broken down into homovanillic acid (HVA), which can be voluntarily gauged from a sample of cerebrospinal fluid (CSF). The experts discovered that the less HVA present in a monkey’s CSF, the less impulse control the monkey displayed. This discovery is the first time an association between this dopamine metabolite and impulsivity has been recorded, and signifies that there could be a biological link connected with the changes in impulse control observed in the monkeys exposed to cocaine in the womb.
Hamilton mentioned it seems that the male monkeys exposed to cocaine in utero have more chances to self-administer the drug, even in low doses, as opposed to controls. Again, the dissimilarity was not seen in female monkeys.
Hamilton quoted, “Our studies indicate that males may be more vulnerable to the long-lasting behavioral and neurobiological consequences of cocaine exposure during gestation than females, suggesting male children who were exposed to cocaine during their mothers’ pregnancies may be predisposed to abuse drugs in adulthood.”
It has been predicted that there are about 7.5 million children in the United States who are exposed to cocaine through gestation and between 30,000 and 160,000 infants born every year who have been prenatally exposed to cocaine, according to the National Pregnancy and Health Survey, the Department of Health and Human Services and previous research.
It is demanding to examine children exposed to cocaine in utero as there could be several other factors that could influence their behavior like less-than-optimal prenatal care, insufficient nutrition, and exposure to numerous kinds and doses of drugs during their mothers’ pregnancies.
The study was presented at the annual Society for Neuroscience meeting in Chicago.