Frontotemporal dementias are a group of fatal and debilitating brain disorders for which there are no cures. Researchers describe how they were able to recreate much of the damage seen in a widely studied form of the disease by growing special types of cerebral organoids in petri dishes. This form of the disease is caused by a genetic mutation in tau, a protein that is a hallmark of Alzheimer's disease and other dementias. By studying these organoids, the scientists discovered how the mutated tau protein may trigger the death of a specific class of neurons known to be vulnerable in frontotemporal dementia. They also showed that they could prevent the death of these neurons by treating the organoids with an experimental drug, originally designed to combat Crohn's disease.