A new study published in the journal Pediatrics on March 18 has revealed a concerning rise in high internalizing behaviors—such as anxiety, depression, and withdrawal—among adolescents in the United States between 1991 and 2021. Interestingly, this trend was accompanied by a significant decline in traditional behavioral health risks, including substance use, sexual risk behaviors, and violence.

The study, led by Rebekah Levine Coley, Ph.D., from Boston College in Chestnut Hill, Massachusetts, analyzed data from 178,658 high school students participating in the national Youth Risk Behavior Survey over three decades. Using latent class analysis, researchers categorized adolescent mental and behavioral health risks into distinct profiles.

The findings identified five key profiles among adolescents. The largest group, referred to as the "Low Everything" profile — adolescents reporting low levels of all risk behaviors — grew from 1999 to 2021, accounting for 48 percent of students.

However, the prevalence of the smallest group, the "High Internalizing" profile — representing 9 percent of adolescents dealing with heightened anxiety and depression — also increased over the same period.

In contrast, there was a marked decline in the prevalence of groups identified as "High Sex" (20 percent), "High Everything" (13 percent), and "High Substance Use" (10 percent). Researchers noted that these declines became even more pronounced during the COVID-19 pandemic.

The study also revealed demographic patterns: younger adolescents were more likely to fall into the Low Everything and High Internalizing categories, while older adolescents were more prevalent in the High Sex and High Everything groups. Female adolescents were more commonly found in the High Internalizing and High Sex categories, whereas males dominated the High Substance Use and High Everything profiles. Additionally, the High Substance Use group had an overrepresentation of White adolescents, while youth of color were more likely to appear in other profiles.

“These analyses provide important information to support the efforts of policymakers, health practitioners, and others who seek to optimize the well-being of U.S. youth,” the authors wrote.

The study’s findings highlight a shifting landscape in adolescent mental health and risk behaviors, underscoring the urgent need for targeted interventions that address internalizing problems such as anxiety and depression, even as progress is made in reducing other risk behaviors.