Scientists have discovered a new genetic risk factor for Alzheimer's disease by screening people's DNA and then using an advanced type of scan to visualize their brains' connections. The researchers discovered a common abnormality in our genetic code that increases the risk of Alzheimer's. To find the gene, they used a new imaging method that screens the brain's connections -- the wiring, or circuitry, that communicates information. Switching off such Alzheimer's risk genes (nine of them have been implicated over the last 20 years) could stop the disorder in its tracks or delay its onset by many years.