Memory lapses, trouble finding words, brain fog: many women describe them around the age of fifty. It is not in the head, or rather it is, in the brain's mitochondria, which lose one of their main supports.
Oestrogen, an ally of mitochondria
Beyond reproduction, oestrogen has a discreet and essential role: it stimulates the production of mitochondria and strengthens their defences against oxidative stress, in the brain, muscle, heart and bone. Women's brains depend particularly on this support, because they consume a great deal of energy.
A review published in August 2026 takes stock of what happens when this support disappears. In postmenopausal women, imaging shows a drop in the brain's glucose consumption and reduced activity of a key enzyme of the respiratory chain, cytochrome c oxidase. In other words, the power plants are running slow.
From energy to inflammation
The slowdown is not the only problem. Poorly functioning mitochondria release more free radicals and let fragments of their own DNA escape. The brain's immune system, the microglia, mistakes these fragments for an infection and triggers low-grade inflammation. This inflammation damages the connections between neurons and hampers the production of the messengers of mood and memory. The authors describe a sequence, energy falling then inflammation rising, that would explain part of the increased risk of Alzheimer's disease in women.
A period, not a fate
This work opens research avenues targeting oestrogen receptors in mitochondria, still experimental. Above all it confirms what we know about everyday levers: physical activity, sleep, a diet that protects mitochondria and medical follow-up suited to this period. Perimenopause is a window in which looking after your mitochondria makes particular sense.
Key points
- Oestrogen supports the brain's mitochondria; its fall at menopause slows them down.
- The energy slowdown leads to low-grade inflammation that weighs on memory.
- The brain fog of perimenopause has a biological basis, and levers to act on.
Sources
- Qiu T, Zhang J, Zhao J. Estrogen withdrawal-induced cognitive impairment in menopausal women: mechanisms and prospects for integrated interventions. International Journal of Molecular Sciences, 2026. https://doi.org/10.3390/ijms27157003
- Wu H et al. Theca cells: active orchestrators of ovarian aging. Reproductive Biology and Endocrinology, 2026. https://doi.org/10.1186/s12958-026-01593-2
- Yang D, Huang H, He Y. Delayed childbearing and reproductive ageing: a narrative review. Journal of Obstetrics and Gynaecology, 2026. https://doi.org/10.1080/01443615.2026.2681760
