By the time we notice signs of cognitive decline due to aging, its often too late to effectively treat it. But taking a look at the brain during the critical window between the ages of 40 and 59 could provide a chance to prevent or slow conditions like Alzheimers disease, according to a study in the Proceedings of the National Academy of Sciences.The study suggests that patients in that window undergo functional MRI (fMRI) and electroencephalography (EEG). Those imaging tests can reveal biomarkers associated with cognitive decline while still providing enough time for effective treatment.An Insight into NeurodegenerationAnticipating the brains decline is tricky since it appears to follow an s-shaped curve rather than a straight line over time. In the study, an international team of neuroscientists detail that curve and identify critical points. They used neuroimaging techniques on more than 19,300 people to define those points.The study shows that the first signs of decline emerge at around age 44, with neurodegeneration hitting peak acceleration at age 67, then plateauing at age 90.Understanding exactly when and how brain aging accelerates gives us strategic time points for intervention, Lilianne R. Mujica-Parodi, a State University of New York, Stony Brook neuroscientist and author of the study, said in a press release. Weve identified a critical midlife window where the brain begins to experience declining access to energy but before irreversible damage occurs, essentially the bend before the break.Identifying Neuronal StressThe researchers have also identified a mechanism: neuronal stress due to not enough fuel. This stress happens to neurons in midlife. Theyre struggling, but theyre still viable, Parodi said. Therefore, providing an alternative fuel during this critical window can help restore function.Besides mapping the brains aging trajectory, the researchers also identified neuronal insulin resistance as one of its key drivers. They saw changes in genes that play a role in metabolism precede shifts in vascular and inflammatory indicators.Food for ThoughtsThe good news? That gap between changes in brain metabolism and those more permanent shifts that could physically impair the brain represents an opportunity for treatment. They also identified an alternative food for neurons that could stave off impairment.They used that food, something called a ketone transporter, in 101 study participants on different points of the brain aging curve. The effects were striking, with the treatment most benefiting participants in the 40-59-year-old group.Rather than waiting to slide down the cognitive decline curve, people might consider tinkering with their metabolism to stave off their brains aging process or consider other strategies to combat cognitive decline. Ketogenic diets or supplements might offer one path forward. If theyre not sure of the state of their mind, they might consider checking their head via brain imaging.Read More: Combat Cognitive Decline With These 5 ActivitiesArticle SourcesOur writers at Discovermagazine.com use peer-reviewed studies and high-quality sources for our articles, and our editors review for scientific accuracy and editorial standards. Review the sources used below for this article:Proceedings of the National Academy of Sciences. Brain aging shows nonlinear transitions, suggesting a midlife critical window for metabolic interventionBefore joining Discover Magazine, Paul Smaglik spent over 20 years as a science journalist, specializing in U.S. life science policy and global scientific career issues. He began his career in newspapers, but switched to scientific magazines. His work has appeared in publications including Science News, Science, Nature, and Scientific American.