A large study of commercially insured children in California found that students whose schools reopened for in-person learning during the COVID-19 pandemic were significantly less likely to receive new diagnoses of anxiety, depression, or ADHD than peers whose schools stayed remote. Girls showed the largest improvements, and mental health–related health care spending also declined, underscoring the role of in-person schooling in supporting youth well-being.
Researchers from Harvard T.H. Chan School of Public Health and collaborating institutions analyzed insurance claims for 185,735 children aged 5 to 18 across 24 California counties, using data from March 2020 to June 2021, according to a summary released by Harvard Chan School and ScienceDaily. The team drew on a commercial insurance claims database together with school-level administrative data from the California Department of Education, taking advantage of California’s varied school reopening timelines as a natural quasi-experiment to compare districts that returned to in-person learning with those that remained remote.
Overall, the study documented an increase in children’s mental health diagnoses during the pandemic, with the share of children receiving a diagnosis rising from 2.8% to 3.5%. However, children whose schools reopened for in-person classes were substantially less likely to receive new diagnoses than those whose schools remained closed. The authors report that by the ninth month after reopening, the probability of being diagnosed with a mental health condition was about 43% lower than during the shutdown period, with reductions seen in anxiety, depression, and attention-deficit/hyperactivity disorder (ADHD).
Health care spending showed a similar pattern. Nine months after schools reopened, non-drug medical spending related to mental health was about 11% lower than during school closures, spending on psychiatric medications was 8% lower, and spending on ADHD-specific medications was 5% lower, according to the Harvard and HealthDay summaries of the study. Girls experienced larger improvements in mental health outcomes and greater reductions in related spending than boys.
“Our results provide solid evidence to parents, educators, and policymakers that in-person school plays a crucial role in kids’ well-being,” said senior author Rita Hamad, a professor of social epidemiology and public policy at Harvard T.H. Chan School of Public Health, in a news release. The researchers suggest that school closures may have contributed to mental health challenges through factors such as reduced social interaction with peers, disrupted sleep schedules, increased screen time, changes in diet, academic difficulties, family stress, and limited access to mental health services that are often provided in schools.
The findings, published December 8, 2025, in the journal Epidemiology, are based primarily on children in relatively higher-income areas who were enrolled in commercial insurance plans, meaning they generally had better access to health care. The authors and Harvard’s news release note that further research is needed to understand how school closures and reopenings affected children from marginalized communities, where mental health impacts could differ or be more severe.
“As we consider future public health emergencies, this study suggests we need to prioritize safe school reopenings and ensure children have access to the social and emotional resources that schools provide,” Hamad said. “Policies should focus not only on infection control, but also on the mental well-being of children, recognizing that schools are a critical part of their support system.” The study was funded by the National Institutes of Health.
