Environments Rife With Social Disparities Fuel Substance Use Disorder Risk, NIDA Director Says

The COVID-19 pandemic made many hidden truths more abundantly clear, said National Institute on Drug Abuse (NIDA) Director Nora Volkow, M.D., during her Annual Meeting presentation on Tuesday. Among them was how powerful the social determinants of health are.

“The people who were forced to work in person were more likely to be infected and more likely to die from infection,” she said, noting how “essential workers” often come from disadvantaged neighborhoods and have less access to good health care.

Given this heightened appreciation of social determinants, Volkow presented some insights into current knowledge on how social determinants of health impact substance use.

“Addiction involves multiple, interacting factors,” she said. “Obviously the environment is tremendously important, since if there is no availability of drugs, then people cannot get addicted. But not everyone exposed to drugs becomes addicted, so genetics and early life factors are critical too.”

It’s that early life period when the social milieu comes into play, Volkow said. Historically, it was believed that substances of abuse became addictive because they offered a strong rewarding stimulus that conditioned people to want more. But recently scientists have found that people who have blunted reward systems are at higher risk of becoming addicted to a substance than those who are sensitive to positive stimuli. Rather, people who are sensitive to negative conditioning (for example, learning quickly not to touch a hot stove after getting burned) are at higher risk of becoming addicted to a substance.

Volkow showed some brain imaging data indicating that for children aged 5 to 8, the environment played a stronger role than genetics in guiding brain development. It makes sense, as this is a key age when children learn to read and start comprehending abstract ideas. “The brain needs continual stimulation,” she said. But in households with dysfunction—such as marital stress, parental mental health issues, and parental incarceration—children tend to receive negative stimulation, typically in the form of abuse and neglect. This can lead to blunted reward conditioning, heightened negative conditioning, and a higher risk of substance use and mental illness.

Making use of new imaging data from over 7,500 children enrolled in NIDA’s Adolescent Brain and Cognitive Development (ABCD) study, Volkow and colleague Dardo Tomasi, Ph.D., illustrated this connection. Their analysis revealed that family income was strongly correlated with volume and thickness of the frontal cortex in children—higher socioeconomic levels were associated with healthier brains. Another imaging analysis conducted during the COVID pandemic uncovered similar results: Among babies born during the pandemic, those whose mothers were under higher stress had greater disruptions in brain structure, and the women most likely to report stress were those with less social and financial support.

While studies like this are important, “we also need studies that can help change policy,” Volkow stressed. Showing a correlation is one thing, but is there evidence that correlation can be changed?

Data suggest yes. Volkow noted one controlled intervention in which 1,000 low-income mothers from several U.S. cities were randomly allocated either a $333 or $20 monthly stipend after the birth of their child. About 400 of the babies were selected for EEG scans at one year of age, and the EEG data found that babies of mothers with the high-cash stipend had more robust and active brain activity.

“This simple monetary intervention probably reduced the mother’s stress on how she would support her child and maybe let them spend more time together,” Volkow said. There was a clear positive neurodevelopmental outcome.

Unfortunately, Volkow acknowledged that the United States may not have the resources right now to implement some of these early-life interventions on a large scale, but building up the infrastructure should be a priority for NIDA and other organizations. It doesn’t require ending poverty—just attenuating the impact of poverty can boost childhood development and prevent susceptibility to substance use down the road. ■