A major new analysis reveals a strong link between repetitive negative thinking, known as rumination, and depression in teenagers.

The research synthesized data from 29 studies involving more than 24,000 adolescents. It found a significant correlation of 0.61 between the two conditions.

The connection was especially pronounced among middle school students, in female-dominated groups, and in studies from Europe and developed nations.

Rumination is characterized by an exhausting mental loop of intrusive, negative thoughts. Previous research has identified it as a vulnerability factor for anxiety and social rejection.

Scientists say this evidence is critical for designing effective prevention and intervention strategies to address adolescent mental health.