Scientists have advanced understanding of the genetic components of Alzheimer’s disease and of brain development with two new studies. The first study has found that certain versions of four genes may speed shrinkage of a brain region involved in making new memories. The brain area, known as the hippocampus, normally shrinks with age, but if the process speeds up, it could increase vulnerability to Alzheimer’s disease, the research suggests. The second article identifies two genes associated with intracranial volume — the space within the skull occupied by the brain when the brain is fully developed in a person’s lifespan, usually around age 20.