Therapeutic targeting of brain bioenergetics in Alzheimer's disease addressing insulin resistance, glucose hypometabolism, and mitochondrial dysfunction.

Alzheimer's disease (AD) is a progressive, age-associated multifactorial neurodegenerative disorder characterised by cognitive decline, synaptic dysfunction, and neuronal loss. Despite over a century of research, effective disease-modifying therapies remain elusive owing to its conundrum pathophysiology. In recent years, AD is increasingly recognised as a complex metabolic disorder characterised by impaired cerebral glucose metabolism, insulin resistance, and mitochondrial dysfunction. These interconnected metabolic disturbances emerge early in the disease state and collectively potentiate other pathologies such as accumulation of amyloid-β (Aβ) plaques, tau hyperphosphorylation, oxidative stress, neuroinflammation, and synaptic dysfunction, thereby establishing bioenergetic failure as a primary factor governing AD progression rather than a downstream phenomenon. While traditional drug development strategies targeting Aβ have failed in clinical trials (limited to monoclonal antibodies), emerging therapeutic models integrating energy failure, thiamine signalling, and insulin-like growth factor (IGF) signalling as upstream events show significant promise in countering downstream neurodegeneration. This chapter summarises the mechanistic framework linking bioenergetic breakdown to AD pathology, with potential therapeutic opportunities aimed at restoring mitochondrial function, enhancing glucose utilisation, and correcting insulin signalling, further opening new avenues for multimodal interventions and identification of progressive metabolic dysfunction biomarkers to aid diagnostic processes.