The brain's energy system has been overlooked in Alzheimer's research, despite its critical role in sustaining neuronal function. This oversight has led to decades of failed drug trials, as the focus has been almost exclusively on the neuron's deterioration. However, the missing piece is not within the neuron itself, but in the energy system that supports it. The brain's metabolic demands are immense, and its energy supply must be finely calibrated to support cognitive functions. Astrocytes, the brain's master energy operators, play a crucial role in this system by extracting glucose from cerebral blood vessels and converting it into lactate, which is then shuttled directly into active neurons during periods of heightened cognitive demand. This lactate is not just fuel, but also a signaling molecule that enhances the activity of NMDA receptors and promotes the interaction between NMDA receptors and CaMKII, the enzyme responsible for translating synaptic activity into lasting structural changes that form the physical basis of memory. When astrocytes are damaged or diseased, as occurs in Alzheimer's and other neurodegenerative conditions, they lose their capacity to produce and transport lactate efficiently, leading to neuronal starvation and death. This reframing of the disease has direct implications for therapeutic strategy, as preserving the functional integrity of the neuron-astrocyte unit must become a central objective of dementia therapeutics. Targeted interventions that support astrocyte metabolism, maintain lactate transfer, and protect the brain's energy infrastructure are needed to prevent irreversible neuronal loss. In my opinion, this is the most logical next step in the fight against dementia, and a fundamental reorientation of research and investment strategies is required to address this critical issue.
