Being exposed to trauma during childhood has been associated with significantly increased risk for developing depression and anxiety later in life. Precisely how trauma translates into greater risk remains unclear, but a variety of mechanisms have been suggested. One of these concerns the timing and pace of puberty as childhood leads into adolescence.

Adolescence is the time in life when research has shown that illnesses including depression and anxiety often begin to appear in vulnerable youths. This is especially the case among females, who are twice as likely to experience internalizing symptoms than males of comparable age. Internalizing symptoms, including depressed mood and anxiousness, are those directed inward (as opposed to externalizing symptoms such as aggression and rule-breaking, which are directed outward and are more often seen in males).

“This sex difference first arises around puberty,” notes a team of researchers led by 2024 BBRF Young Investigator Divyangana Rakesh, Ph.D., of King’s College, London, UK, in a new study appearing in the Journal of Child Psychology and Psychiatry. First author of the new paper was Niamh MacSweeney, Ph.D.

While recent evidence suggests that internalizing symptoms are becoming more common in female adolescents, some research has suggested that “adolescents, and especially females, who begin puberty ahead of their same-age, same-sex peers are at an increased risk” for such symptoms.

Why would this be the case? Dr. Rakesh, whose BBRF Young Investigator project is examining “pathways to risk and resilience in adolescence,” and specifically about puberty and the pace of biological development, notes with her co-authors that exposure to threat may be an important predictor of the early onset of puberty, which, in turn, may contribute to the emergence in adolescence of internalizing symptoms.

There is a paucity of research following children over time as they move into and through puberty, although it is known that pubertal maturation varies substantially in timing and in tempo among individuals. In their newly published study Dr. Rakesh and colleagues tried to discover whether earlier onset of puberty and/or its faster progression had an impact on the development in young females of internalizing symptoms. They also explored whether those exposed to trauma in childhood and those who were not had different risk profiles.

“What is unique about our paper was that we examined individual variability in pubertal developmental trajectories,” Dr. Rakesh says. Analysis of variables affecting trajectories “may help identify youth who may be most in need of additional support during adolescence,” the researchers note.

The team made use of the largest source of neuroimaging data in the world that is following a cohort of youths from childhood through adolescence. Called the Adolescent Brain Cognitive Development (ABCD) study, it includes some 11,800 young people who in 2016-18 were recruited at ages 9-10 at 21 sites by the U.S. National Institutes of Health. As the study has progressed, datasets have been released for analysis by members of the scientific community. The study by Dr. Rakesh and colleagues makes use of data from 4,225 female youths at four time points: at the time of recruitment (average age 10) and in three subsequent years, in the final of which the children being studied were an average age of 13.

Some 63% of the girls in the cohort had no trauma exposure in their childhood years. About 1 in 4 had experienced 1 traumatic event, and about 1 in 10 had experienced 2 or more. The team notes that these figures are about exposure to trauma; they do not necessarily mean that each girl experienced the event as traumatic—a distinction which might be addressed in future studies. 54% of the cohort was identified as White; 13% Black; 20% Hispanic; and 2% Asian; nearly 60% had parents with a college degree or greater; and 46% came from a household with income $100,000 or greater.

The team first analyzed data on how puberty unfolded among the approximately 4,000 girls. They fell into three groups: in relative terms, 9% were deemed “early starters”; 76% were “typical developers”; and 15% were “slow developers.”

While the smallest group overall, the early starters in puberty were found to have had higher levels of early-life trauma exposure, compared to typical developers and slow developers. Slow developers had the least trauma exposure, on average. These relationships, while suggestive, do not necessarily imply a causal relationship.

The second major question was about a possible relationship between early trauma exposure and the development of internalizing symptoms. Here, girls with greater exposure to trauma were found to be at increased risk for internalizing symptoms at ages 12-14 years—and this, in turn, was found to be related to their pubertal status at ages 9-10. Those with greater trauma exposure and at greater risk for internalizing symptoms were, on average, found to have been further along in the puberty development process at age 9-10.

Developmental status as puberty was getting under way was related to prior trauma exposure and risk of internalizing symptoms. But no such relationships could be established regarding the pace of puberty development. A faster puberty progression did not correspond with past exposure to trauma or higher risk for internalizing symptoms by ages 12-14.

“Accelerated pubertal development may be a mechanism through which trauma exposure in childhood increases risk for internalizing symptoms in female youth” the team wrote, but “accelerated” here signifies an earlier age of onset of the puberty process, not the pace at which it proceeded.

The data in this study makes it impossible to connect the dots mechanistically. The team notes that animal studies have given rise to the theory that early exposure to trauma may heighten the body’s stress response and lead to the premature influx of adrenal and gonadal hormones that may result in early onset of puberty in males and females. Starting puberty later might then possibly be due to a shortened window of sensitivity to sex-steroid-related neural changes, and thus may possibly be “protective” relative to the risk of developing internalizing symptoms. Still, it is possible, the team notes, that early trauma’s impact on such symptoms may involve mechanisms other than or in addition to early pubertal timing.