Loneliness and a desire to be thinner may help explain higher rates of depressive symptoms in adolescent girls

by Ingrid Fadelli, Medical Xpress

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edited by Lisa Lock, reviewed by Robert Egan

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Adolescence, the critical developmental stage between childhood and adulthood, is often marked by significant changes in friendships, appearance, preferences and attitudes. For some young people, it can be a tumultuous period accompanied by substantial emotional distress.

Past studies suggest that girls are more likely than boys to experience internalizing problems—emotional difficulties that include depressive and anxiety symptoms. The reasons for this difference, however, remain poorly understood.

Researchers at the Tokyo Metropolitan Institute of Medical Science, King's College London and other institutions recently analyzed data from thousands of adolescents in Japan to investigate the possible reasons for these sex differences. Their findings, presented in a paper published in Nature Human Behaviour, suggest that loneliness and a desire to be thinner could partly account for differences in depressive symptoms and thoughts about suicide.

"Girls are at higher risk of internalizing problems than boys," wrote Zui C. Narita, Gemma Knowles and their colleagues in their paper. "This disparity has widened in recent decades, but the underlying mechanisms remain understudied. We analyzed data from 3,171 adolescents (46.9% girls) within the Tokyo Teen Cohort, assessed at ages 12, 14 and 16 years."

Exploring the sources of young people's distress

Depression is a common psychiatric disorder in adults and adolescents. Symptoms include persistent low mood, decreased interest in daily activities, changes in eating and sleeping patterns, low energy and a loss of motivation.

Thoughts about suicide, clinically referred to as suicidal ideation, are also fairly common among adolescents experiencing emotional distress. Narita, Knowles and their colleagues wanted to understand whether loneliness and a desire to be thin were more prevalent in female adolescents, potentially contributing to sex-related differences in internalizing problems.

They analyzed the responses of 1,487 girls and 1,684 boys in Japan who were assessed at ages 12, 14 and 16 as part of an initiative called the Tokyo Teen Cohort. Using statistical methods, the researchers tried to determine whether the loneliness and desire for thinness reported by these young people at age 14 could account for their mental health outcomes at age 16.

"At age 16, girls showed higher prevalence of internalizing problems than boys: depressive symptoms (15.9% versus 8.2%) and suicidal ideation (29.8% versus 18.1%)," wrote the authors. "Coproduction with young people suggested loneliness and desire for thinness as candidate pathways. Using the mediational g-formula, we estimated that the effect through these factors at age 14 relative to the total effect of female sex was 34.7% for depressive symptoms and 46.3% for suicidal ideation at age 16."

Initial insights that could inform future research

The results suggest that loneliness and a desire for thinness could together account for a substantial proportion of the differences between adolescent girls and boys in depressive symptoms and suicidal ideation. Further research could identify other factors that may contribute to these differences.

"These findings suggest that social intermediates may contribute to the higher prevalence of internalizing problems among girls in this cohort, highlighting potential targets for interventions and policies informed by young people," wrote the authors.

The work could help guide new interventions to offer emotional and psychological support to young people during adolescence.

Written for you by our author Ingrid Fadelli, edited by Lisa Lock, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.

Publication details

Zui C. Narita et al, Loneliness and desire for thinness explain sex differences in adolescent internalizing problems, Nature Human Behaviour (2026). DOI: 10.1038/s41562-026-02578-2

Journal information: Nature Human Behaviour

Key medical concepts

Depression, EmotionalLonelinessSuicidal ideation

Clinical categories

PsychiatryPsychology & Mental healthPediatricsChildren's health Who's behind this story?

Ingrid Fadelli

Freelance journalist with BSc Psychology and MA International Journalism. Covers AI, robotics, neuroscience, and astrophysics since 2018. Full profile →

Lisa Lock

BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator. Editing for Science X since 2021. Full profile →

Robert Egan

Bachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →

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