Ketogenic diets: an historical antiepileptic therapy with promising potentialities for the aging brain.

Ketogenic diets (KDs), successfully used in the therapy of paediatric epilepsy for nearly a century, have recently shown beneficial effects also in cancer, obesity, diabetes, GLUT 1 deficiencies, hypoxia-ischemia, traumatic brain injuries, and neurodegeneration. The latter achievement designates aged individuals as optimal recipients, but concerns derive from possible age-dependent differences in KDs effectiveness. Indeed, the main factors influencing ketone bodies utilization by the brain (blood levels, transport mechanisms, catabolic enzymes) undergo developmental changes, although several reports indicate that KDs maintain some efficacy during adulthood and even during advanced aging. Encouraging results obtained in patients affected by age-related neurodegenerative diseases have prompted new interest on KDs' effect on the aging brain, also considering the poor efficacy of therapies currently used. However, recent morphological evidence in synapses of late-adult rats indicates that KDs consequences may be even opposite in different brain regions, likely depending on neuronal vulnerability to age. Thus, further studies are needed to design KDs specifically indicated for single neurodegenerative diseases, and to ameliorate the balance between beneficial and adverse effects in aged subjects. Here we review clinical and experimental data on KDs treatments, focusing on their possible use during pathological aging. Proposed mechanisms of action are also reported and discussed.