Alzheimer’s as a Disorder of Lost Metabolic Signaling: Brain Insulin Resistance as an Adaptive Metabolic Failure Preceding Neurodegeneration

Alzheimer’s disease is traditionally characterized by the accumulation of amyloid plaques and tau tangles, yet metabolic dysfunction in the brain often precedes the appearance of these pathological features by years or decades. This article proposes that Alzheimer’s may be more accurately understood as a disorder of lost metabolic signaling, in which brain insulin resistance emerges as an adaptive response to chronic metabolic and inflammatory stress rather than as a primary defect. By integrating evidence from insulin signaling, mitochondrial function, energy buffering, and alternative substrate utilization, this framework suggests that neurodegeneration reflects a progressive loss of regulatory coherence rather than isolated molecular failure. Reframing Alzheimer’s in this way highlights the importance of timing, metabolic context, and system-level regulation, and helps explain the limitations of late-stage, pathology-focused interventions while pointing toward earlier windows of vulnerability and preservation.