Ketones are an efficient energy substrate for the brain. The scientific evidence does not suggest that therapeutic levels of ketosis are damaging to the brain or nervous system over a long period of time.
However, conditions such as the ketogenic diet and calorie restriction, which are characterized with an elevation in blood ketones, confer many neuroprotective effects. Many studies suggest the neuroprotective effects due to ketone metabolism. Thus, it is likely that exogenous ketones would have similar effects. It may even prevent neurodegeneration, as impaired glucose metabolism often accompanies the development of dementia such as in Alzheimer’s disease. Providing another energy source to the brain in these circumstances could be very protective. There is ongoing research on this topic.