King's College London Mar 25 2025 Depression is a mental health condition that affects 280 million people worldwide. It is twice as common in women than men and this pattern starts to develop during adolescence. Researchers have studied the biological processes that drive depression in adults and shown a potential role for the kynurenine pathway, but this is the first time it has been investigated in adolescents in relation to biological sex.  The study was published in Biological Psychiatry