The purpose of this narrative review is to synthesize current evidence supporting insulin resistance as a shared pathophysiological driver across neurodegenerative, neurological, and neuropsychiatric conditions, and to evaluate the potential of nutrition- and metabolism-based interventions as modulatory strategies.<h4>Recent findings</h4>Recent human and experimental studies demonstrate that central insulin resistance disrupts brain energy metabolism, promotes neuroinflammation, impairs synaptic plasticity, and alters neuronal network stability. The gene discussed is INS; the disease is Insulin resistance.