Hormone therapy was once linked to dementia. A huge study found it might lower risk — if you start early enough.

A growing body of evidence suggests hormone therapy can protect the aging brain, if it's timed right. Fiordaliso/Getty Images Hormone therapy may protect a woman's aging brain, but timing is critical. Experts agree the "window of opportunity" for HRT is typically in the late 40s or early 50s. "Early intervention promotes and sustains brain health," neuroscientist Roberta Brinton said. Get in there early. That seems to be the growing consensus around hormone replacement therapy (HRT) for women. New study data suggests that middle-aged women could use these treatments to protect their brains, contradicting old concerns about a potential dementia risk. There is a caveat to this good news: You probably have to adhere to what researchers are calling the golden "window of opportunity" before the brain hardens and ages too much.