Women’s brains show surprising protection early on — and estrogen related genes may be why

A large international study has found a striking difference between men and women who show an early sign of Parkinson’s. Researchers looked at brain scans from people with isolated REM sleep behaviour disorder, a condition that often comes years before motor symptoms, and found that women had far less brain shrinkage than men despite being the same age and having similar clinical profiles. The team gathered nearly 900 brain scans from nine centres around the world and, after quality checks, analysed 687 of them. What stood out was how little of the outer brain layer, the cortex, was thinner in women. In men about 37 per cent of cortical regions showed thinning. In women only about 1 per cent were affected. The difference was biggest in areas that control movement, sensation, vision and spatial awareness. To dig into why this might be happening, the researchers matched the brain imaging patterns with maps of gene activity in the healthy brain. That analysis pointed to genes linked to oestrogen related receptors, notably ESRRG and ESRRA. These receptors are involved in the way cells make and use energy, especially in mitochondria, the tiny power stations inside cells. That matters because dopamine producing neurons, the ones that fail in Parkinson’s, are particularly vulnerable when energy systems are stressed. In plain terms, the study suggests that parts of the female brain may be better protected from early damage, and that oestrogen related pathways could be part of the reason. Those pathways help keep cells fuelled and alive, which could slow the early atrophy that leads, over time, to the symptoms we all recognise. This matters for research and treatment in a couple of ways. First, it argues that sex should be treated as a key biological factor in trials. Men and women may respond differently to treatments, and separating them in study design could make trials clearer and more efficient. Second, the genes the study highlights could be new targets for therapies. Lab work already hints that boosting ESRRG activity can protect dopamine neurons from toxic proteins that build up in Parkinson’s. There are caveats. The analysis used people with a precursor sleep disorder because it offers a rare early window, before major motor problems appear. That is a strength, but it also means the findings may not translate exactly to all people with established Parkinson’s. The study shows association rather than direct cause, so more lab experiments and clinical work are needed to test whether targeting those oestrogen related pathways can be turned into a safe, effective treatment. For people living with Parkinson’s, the headline is hopeful. The research points to biological reasons why women often experience slower progression and suggests a route to treatments that might protect brain cells. For scientists and drug developers, it gives a clearer map of where to look next: energy metabolism, oestrogen related receptors, and how those systems protect key brain circuits.