Linguistic models that analyzed the words children used when talking about stressful events proved better at predicting future mental health problems than a panel of human experts.
In a study published in Nature Mental Health , researchers used four natural language processing models to evaluate recorded interviews of more than 200 children, ages 9 to 13, as they talked about stressful events in their lives. The models were very accurate at predicting whether these same children developed mental health conditions six years later.
Across the models, the researchers found that the style of the children's speech mattered more than the content. In other words, how children constructed their sentences—such as use of small connector words like and, to, and but—was more predictive than the children's actual descriptions of stress.
"We believe this study provides a robust proof of concept for the development of scalable tools that identify markers of risk before individuals are diagnosed," said Chase Antonacci, the study's lead author and a neuroscience doctoral student in Stanford's School of Humanities and Sciences (H&S).
Adolescence is when depression and anxiety most often emerge, and once these disorders take hold, they are notoriously difficult to treat, Antonacci noted. The years leading up to diagnosis are a critical but poorly understood window, and clinicians have had no scalable way to identify which children are on a path toward illness.
Prior to this work, a number of methods were available to assess mental health risk in children, typically involving clinician assessments, but none could be feasibly implemented for large groups. More objective methods require blood draws or specialized equipment to measure the stress hormone cortisol, physiological reactions to stress, or the length of telomeres–the protective caps on chromosomes that shorten under chronic psychological distress.
"These factors—cortisol, stress reactivity, and telomere length—all have some predictive utility, but speech is something that is inexpensive and scalable," said Ian Gotlib , the study's senior author and professor of psychology in H&S. "It's easy, it's accessible, and it may be a stronger predictor of the development of problems than any of these other factors alone."
Long-term studies help identify problems early
Gotlib's lab at Stanford studies early-life stress and the ways that the environment shapes children's brain development and increases risk for mental health problems. His team originally conducted the in-depth interviews used in the current study as part of a larger project that is following a group of young people over many years.
The audio-recorded interviews with the 9- to 13-year-olds are each about 1.5 hours long and cover a range of topics including stressful events. The researchers first interviewed the children using a traumatic events screening inventory, also known as TESI. For this inventory, a panel of experts reviewed the interviews and rated the severity of each child's stressors, which can range from financial insecurity and parental divorce to abuse and experiencing a natural disaster. The panel then assigned a single number that reflected the child's cumulative experience of stress.
"We realized that there was probably so much richness, variability, and nuance that we were losing by reducing these clinical interviews to a single number, so we thought about other ways we could leverage those audio recordings," Antonacci said.
For the current study, the researchers analyzed the interviews using four different natural language processing models. These models have been used in other research to detect signals of mental health and emotional functioning but have mostly been applied to text written by adults to identify current symptoms. Because young children do not generally write as much as adults do, the team wanted to see whether these models could be used to analyze recorded interviews of children's speech to predict who would develop disorders up to six years later.
The results across the models highlighted the predictive power of linguistic style. This is consistent with previous research showing that patterns in the use of certain words, such as a focus on first-person pronouns and frequent use of prepositions and conjunctions, are indicative of mental health issues.
While not as predictive as linguistic style, the content of the speech did show important links to either future problems or resilience. The statements associated most strongly with risk described extreme physical violence such as being punched or choked or harsh social exclusion such as feeling an entire school was against them. Resilience was linked with statements about social support and activities like sports and school clubs. Notably, mentions of mental healthcare itself–references to therapists or counselors–emerged as one of the strongest protective signals.
The findings show great potential for a language-based assessment, but the next step involves testing the models with a larger dataset, Gotlib said.
"If these findings hold, it means we may be able to just take smartphone recordings of children talking, analyze that speech, and identify which children are at risk, years before they might develop a disorder," he said.
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Gotlib is the Marjorie Mhoon Fair Professor in H&S and a member of Bio-X, the Maternal & Child Health Research Institute, the Wu Tsai Neurosciences Institute, and the Stanford Center on Longevity.
Additional Stanford co-authors on this study include psychology doctoral students Eugenia Giampetruzzi and Sabrina Jones; computer science undergraduate Kaitlyn Kwan; and psychology postdoctoral scholar Jessica Uy.
James W. Pennebaker of the University of Texas at Austin is also a co-author on this study. Pennebaker developed the Linguistic Inquiry and Word Count (LIWC) software used in this study and receives royalties from its sale and licensing.
This work was supported by the National Institute of Mental Health and the National Science Foundation.
