News · Brain & Mental Health
Loneliness and wanting to be thinner may explain much of why teenage girls report more depression than boys
Girls are more likely than boys to struggle with depression in adolescence, and the gap has grown. Following 3,171 young people in Tokyo from age 12 to 16 pointed to two social pressures that young people themselves identified.
- This observational cohort study followed 3,171 adolescents in Tokyo at ages 12, 14 and 16.
- At 16, 15.9% of girls had depressive symptoms compared with 8.2% of boys.
- Young people helped choose loneliness and the desire to be thinner as the pathways to test.
- Those two factors at 14 accounted for about a third of the gap in depressive symptoms at 16.
- The findings suggest targets for support, but the study cannot prove that changing them would help.
In adolescence, girls struggle with low mood more often than boys, and research shows the gap has widened in recent decades. A study that followed 3,171 young people in Tokyo from age 12 to 16 has tried to find out why, and it started by asking young people what they thought was going on.
Their answers were loneliness and the pressure to be thin. Together, those two factors at age 14 accounted for a large share of the difference between girls and boys two years later.
Why do teenage girls report more depression than boys?
The authors note that girls are at higher risk of internalizing problems than boys. Internalizing problems are emotional difficulties turned inward, such as depression, anxiety and thoughts of suicide.
Knowing that a gap exists is not the same as knowing what drives it. Many things could contribute, and the authors say the underlying mechanisms remain understudied. If some of the gap comes from social experiences, those experiences might be things schools, families and policies can change.
How did young people help design the teen study?
The research, published in Nature Human Behaviour, used data from the Tokyo Teen Cohort, which checked in with the same adolescents at ages 12, 14 and 16. Just under half, 46.9%, were girls.
Before testing explanations, the team worked with young people in a process called coproduction. Rather than researchers alone choosing what to test, young people helped decide which pathways seemed most plausible from their own experience. They suggested two: loneliness, and a desire to be thinner.
That choice gives the study an unusual grounding. The factors tested were not just what adults assumed mattered, but what young people said was affecting them.
How big was the depression gap at age 16?
By 16, the difference was stark. Depressive symptoms were found in 15.9% of girls compared with 8.2% of boys. Thoughts of suicide were reported by 29.8% of girls and 18.1% of boys.
Those figures are a reminder of how common these struggles are for teenagers of any sex. Nearly one in five boys and three in ten girls reported suicidal thoughts at some level by 16.
How much did loneliness and body image explain?
The team used a statistical method called the mediational g-formula, which estimates how much of the link between being a girl and later depression runs through factors measured in between, while accounting for other influences measured earlier.
Loneliness and the desire to be thinner at age 14 accounted for an estimated 34.7% of the sex difference in depressive symptoms at 16. For suicidal thoughts, the share was higher, at 46.3%. In plain terms, these two social pressures appear to carry roughly a third to nearly half of the extra risk girls faced.
What can’t a teen cohort study prove?
It cannot prove that loneliness or body-image pressure causes depression. The study is observational, and methods like this rely on assumptions, including that the important confounding factors were measured. It is also possible that early low mood made some teenagers lonelier, rather than only the other way around.
The results come from one city in Japan, and pressures around appearance and friendship differ between cultures, so the numbers may not transfer directly elsewhere. The full paper, including its detailed limitations, sits behind a paywall that was not reviewed for this article. And about two-thirds of the gap in depressive symptoms was not explained by these two factors.
What does the loneliness finding mean for families and schools?
The authors suggest these social intermediates may be potential targets for interventions and policies informed by young people. That points toward efforts that help teenagers feel connected and that ease pressure around body shape, although this study did not test any such program.
For any teenager who is struggling now, help exists. MedlinePlus says mental health problems can be treated, and suggests that young people talk to a parent, school counselor or health care provider. It also lists warning signs worth taking seriously, including feeling very sad, hopeless or worthless, and eating or exercising obsessively.
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What did the study find?
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%). The effect through loneliness and desire for thinness at age 14, relative to the total effect of female sex, was estimated at 34.7% for depressive symptoms and 46.3% for suicidal ideation at age 16.
What are internalizing problems?
Emotional difficulties that are directed inward, such as depression, anxiety and thoughts of suicide, as opposed to outward behavior problems.
What does coproduction mean here?
Young people worked with the researchers to decide which explanations were worth testing. They pointed to loneliness and the desire to be thinner.
Does this mean loneliness causes depression in girls?
Not on this evidence. The study estimates how much of the sex gap runs through these factors under a set of assumptions, but it is observational and cannot prove cause.
Does this apply outside Japan?
It is not certain. The cohort was in Tokyo, and social pressures around appearance and friendship can differ between countries.
Where can a teenager get help?
MedlinePlus says mental health problems can be treated, and suggests talking to a parent, school counselor or health care provider. This is general information rather than medical advice.