Years of research clarify impact of prenatal cocaine exposure

A 1990s flurry of federally supported research that was launched at a time when news headlines screamed of “crack babies” has transitioned today to a couple of still-active projects with subjects who have been tracked from birth into their 20s. A lead researcher at one of these sites tells Addiction Professional that the conclusions that can be drawn from the two-plus decades of research are somewhat more nuanced than what those early headlines conveyed.

“The idea that these were 'monster children,' that's not really the truth,” says Sonia Minnes, associate professor at Case Western Reserve University's Jack, Joseph and Morton Mandel School of Applied Social Sciences. “But they do have patterns of problems.”

Minnes emphasizes that even small disabilities in this group of young people can translate to significant societal costs, as well as barriers to success in adulthood.

The Cleveland site is one of only two locations from the National Insititute on Drug Abuse (NIDA)-supported Project Newborn where cocaine-exposed individuals are still being followed. The most recently published findings for the Case Western Reserve cohort, covering substance use patterns and coping mechanisms for children at ages 15 and 17, appeared in the journal Drug and Alcohol Dependence. Some of the key findings in these reports show that youths who were exposed to cocaine in utero are twice as likely to use marijuana and tobacco at 15 and to have a substance use disorder at 17 than youths who were exposed to other substances but not cocaine.

Study history

Minnes says the researchers at Case Western Reserve are presently gathering data for cocaine-exposed individuals who are now in their 20s. She says that aspects of the original study design have helped the research team reach this stage while other Project Newborn sites have ceased collecting data.

“We've had a good retention rate,” Minnes says. “One of the factors that was used at the beginning to retain people was to make it easier for people to see us. One cab driver did all of our visits,” so there weren't any transportation challenges for the young people's families.

She adds that the program sought to establish a connectedness with mothers and their children, built on respect for the families. “They got our undivided attention when they came here,” she says.

Other seemingly simple gestures, such as serving food when the families visited, made a big difference. One 20-year-old who has been with the project from the start recently told Minnes that she keeps coming back in part because she likes helping people.

The original study cohort in Cleveland comprised 415 individuals, with two evenly divided groups of individuals prenatally exposed to cocaine and other substances and individuals with polydrug exposure that did not include cocaine. This was designed to ensure that both study groups were made up of at-risk individuals, a factor that makes for a more reliable analysis of cocaine's specific effects.

In the earliest research, all of the study sites saw an effect of prenatal cocaine exposure on restricted fetal growth. Later on, the Case Western Reserve researchers were not finding significant between-group differences in IQ, but patterns in perceptual reasoning were indicating that the cocaine-exposed group was demonstrating deficits in executive functioning, and this has endured in later years. Patterns of increased aggression and issues such as conduct disorder also emerged, says Minnes.

It is important to remember that while one cannot conclude from this research that prenatal exposure to cocaine causes such problems, a research design with a carefully constructed control group offers strong evidence of an association, Minnes explains. Among the variables considered, “We controlled for the child's home environment, and we controlled for maternal or caregiver level of psychological distress,” she says.

As part of what is anticipated to be the last age range studied, Minnes says, the Case Western Reserve researchers also will look at what factors influence positive outcoimes for these children.

She adds that the team also has examined the dynamic of out-of-home placement for some of these children. Half of the cocaine-exposed children were taken out of their mother's custody, moved either to the care of a family member or to the foster care system. Out-of-home placement did not occur in the control group of non-cocaine exposed children.

General conclusions

Minnes says that the years of research into cocaine-exposed children have achieved these generally accepted conclusions:

• After controlling for other factors affecting substance use, researchers have found that cocaine-exposed youths have higher use rates.

• There is a strong association between cocaine exposure and deficits in executive functioning and attention.

• There is a less strong but still fairly consistent association between cocaine exposure and language deficits.

• There is evidence of increased externalizing behaviors in the cocaine-exposed group, and this persists through the teenage years.