Eat to Maintain Your Declining Intelligence?

First the bad news. The age-related deterioration in human brain pathways starts in the early 40s (https://www.theguardian.com/science/2020/mar/06/low-carb-diet-may-reverse-age-related-brain-deterioration-study-finds). Second, the better news. It appears that the decline can be somewhat delayed by a low carbohydrate diet. Glucose makes things worse (so limit high energy drinks) whereas ketones, which are released when non-carbohydrate energy substrates are used, reduce the rate of neural pathway decline (and the associated loss of intellectual acuity?).