Defects in insulin receptors at the blood–brain barrier contribute to brain insulin resistance and affect β-amyloid pathology in Alzheimer’s disease (AD), a study published on Tuesday reports. The study clarifies the mechanisms of insulin activity in microvessels of the brain and provides evidence of insulin resistance at the level of the blood-brain barrier. The findings supporting the idea that AD is a neurodegenerative disease with a strong metabolic component and may expand the range of drugs that could be tested for AD.