A female figure stands in front of an illuminated window showing an abstract female head

Illustration: Kim Salt

Sad times are inevitable, and most people eventually rally. But clinical depression is different, and more brutal. All sense of well-being evaporates; life can seem not worth the trouble. According to one estimate, more than 60% of people worldwide who have attempted suicide have a depressive disorder (S. Borentain et al. BMC Psychiatry 20, 384; 2020).

Antidepressant drugs are commonly prescribed as treatment, but none is universally helpful. Other types of therapy are beginning to enter the scene, from psychedelic compounds such as psilocybin to implanted devices that zap the brain with pulses of electricity.

The causes of depression are manifold and complex. But biologically definable factors are starting to come to light. One theory that is gaining support is that the culprit might be a slowdown in nerve growth — meaning that measures that encourage neurons to form could help to keep depression at bay. Obesity has been found to be both a cause and a consequence of depression in a vicious circle. And the disruptions of ancient sleep patterns by electric lighting, smartphones and other modern conveniences are wreaking havoc on our mental health. Researchers around the world are finding links between depression and COVID-19, heart health, exercise and the use of social media.

Perhaps surprisingly, depression rates are rising fastest in young people. The condition is also disproportionately experienced by women, because the ebb and flow of hormones during pregnancy, after childbirth and during menopause can trigger biochemical cascades that result in the condition. These hormonal effects are very common around the time of menopause — and yet, the link is still ignored by many health-care professionals.

If you or someone you know is contemplating suicide, please reach out. You can find help through a suicide-prevention phone line. In the United States, you can call the Suicide & Crisis Lifeline on 988. In the United Kingdom, you can call the Samaritans on 116 123. For alternative options and help in other parts of the world, see go.nature.com/crisis-help.

We are pleased to acknowledge the financial support of Sage Therapeutics and Biogen in producing this Outlook. As always, Nature retains sole responsibility for all editorial content.