Fatigue, loss of interest, thoughts going round in circles: depression affects millions of people, and its causes remain poorly understood. A review published in July 2026 in Molecular Psychiatry proposes a lead that links three players: mitochondria, inflammation and the brain.
An energy drop that shows up in the cells
People with depression often describe an exhaustion that rest does not repair. Researchers are now looking at mitochondria, the power plants that produce the energy of every cell, including those of the brain. Several lines of work converge: in people affected, energy production is less efficient, mitochondrial DNA is more fragile and oxidative stress is higher.
The review gathers these observations and places them in a broader picture. For its authors, depression is not a simple breakdown of mitochondria: it is a system that goes off balance, with several possible starting points.
A loop between energy and inflammation
When mitochondria are damaged, they release fragments of their own genetic material, which the immune system mistakes for an alarm signal. The result is low-grade inflammation, which in turn wears the mitochondria down. This loop could explain why some people with depression have high levels of inflammation in their blood.
A human study published in June 2026 in Brain, Behavior, and Immunity points the same way. It followed 178 adults with depression, none on medication at the time of the study. Among those with the most monocytes, a type of immune cell, self-reported motivation was lower. In a second group of 40 patients, the cells of the most inflamed people produced more of their energy through sugar metabolism, a more costly pathway. These are associations observed in people at one point in time, linking a measure of metabolism to a measure of motivation.
What treatments are known to do
According to the review, classic antidepressants also seem to act on mitochondria: they gradually restore their function and reduce oxidative stress and inflammation. Other, more recent approaches are being explored. These data combine animal studies and studies in humans. They describe the mechanism and guide research into new approaches.
What this changes, concretely
This work describes a mechanism that is still being explored. Above all, it gives a reason to take depression seriously as a disease of the body as much as of the mind, and it opens the way to new research directions. For anyone concerned, the first step remains a medical consultation.
Key takeaways
- Depression goes with signs of mitochondrial dysfunction and inflammation.
- Cellular energy and inflammation feed each other.
- The data combine animal studies and studies in humans.
- These leads never replace medical follow-up.
Sources
- Wang Y, Li JT, Zhu LL, Wu YK, Su YA, Si TM. Mitochondrial-inflammation crosstalk in major depressive disorder: molecular mechanisms and therapeutic implications. Molecular Psychiatry, 2026. https://doi.org/10.1038/s41380-026-03732-y
- Bekhbat M, Craig G, Wommack EC, et al. Monocyte abundance and glycolytic reprogramming associate with motivational impairment in depression. Brain, Behavior, and Immunity, 2026. https://doi.org/10.1016/j.bbi.2026.106882
