A study suggests that some patients diagnosed with behavioral-variant frontotemporal dementia (bvFTD)—an incurable condition that robs patients of the ability to control their behavior—may instead have a cerebrospinal fluid leak, which is often treatable. Cerebrospinal fluid (CSF) circulates in and around the brain and spinal cord to help cushion them from injury. When this fluid leaks into the body, the brain can sag, causing dementia symptoms. Schievink said many patients with brain sagging—which can be detected through MRI—go undiagnosed, and he advises clinicians to take a second look at patients with telltale symptoms. Clinicians can also ask about a history...