A new study from Cedars-Sinai has revealed an unexpected reason behind some cases of a serious form of dementia.
The research suggests that a number of people diagnosed with behavioral-variant frontotemporal dementia may actually have a very different and potentially treatable condition: a leak of cerebrospinal fluid.
Behavioral-variant frontotemporal dementia, often called bvFTD, is a form of dementia that mainly affects behavior, personality, and decision-making. People with this condition may act very differently from their usual selves.
They may lose their sense of judgment, behave in socially inappropriate ways, or struggle to think clearly. Families often find these changes shocking and distressing because the person’s personality seems to change dramatically.
Frontotemporal dementia is usually considered a progressive brain disease. This means it tends to worsen over time and has no cure. However, the Cedars-Sinai researchers discovered that in some patients, the symptoms that look like dementia may actually be caused by something very different.
The key problem involves cerebrospinal fluid, often shortened to CSF. This clear fluid surrounds the brain and spinal cord. It plays several important roles in the body. The fluid cushions the brain, protects it from injury, removes waste, and helps maintain a stable environment for the nervous system.
Sometimes, however, this fluid can leak from the spinal canal. When that happens, the pressure that normally supports the brain drops. Without enough support from the fluid, the brain can slowly sink or sag downward inside the skull. Doctors call this condition “brain sagging.”
When the brain sags, it can affect areas that control personality, behavior, and thinking. As a result, patients may develop symptoms that closely resemble frontotemporal dementia. These symptoms can include memory problems, confusion, personality changes, and difficulty planning or making decisions.
Because the symptoms look so similar to dementia, many patients are diagnosed with a degenerative brain disease. Unfortunately, the real cause—a fluid leak—may remain hidden.
The Cedars-Sinai research team wanted to understand whether some people with these dementia-like symptoms might actually have undetected CSF leaks. Their findings were published in the journal Alzheimer’s & Dementia: Translational Research and Clinical Interventions.
The scientists studied 21 patients who had symptoms of behavioral-variant frontotemporal dementia and also showed signs of brain sagging on brain scans. These patients had been struggling with changes in thinking and personality that resembled dementia.
Doctors have several ways to look for cerebrospinal fluid leaks. One common method is called a CT myelogram. This test involves injecting a special dye into the spinal fluid and using imaging scans to track where the fluid goes. However, the Cedars-Sinai researchers suspected that traditional scans might miss certain types of leaks.
In particular, they focused on a type of leak known as a CSF-venous fistula. In this condition, cerebrospinal fluid escapes directly into nearby veins instead of staying within the spinal system. Because the fluid drains into the bloodstream, the leak can be very difficult to detect with standard imaging.
To solve this problem, the researchers used a more advanced scanning technique that tracks how the contrast dye moves through the spinal fluid over time. This approach allowed them to see leaks that traditional scans might miss.
Using this method, the team discovered CSF-venous fistulas in nine of the 21 patients. These patients then underwent surgery to seal the leaks.
The results were striking. After the leaks were repaired, all nine patients showed a complete reversal of brain sagging. Even more remarkable, their dementia-like symptoms disappeared. Their thinking improved, their behavior returned to normal, and their personalities stabilized.
For the remaining 12 patients, doctors were unable to identify a clear source of the fluid leak. These patients received more general treatments aimed at improving spinal fluid pressure. However, only three of them experienced noticeable improvement. This finding highlights how important it is to locate the exact source of a leak so it can be repaired directly.
The study provides an important new perspective on dementia diagnosis. It suggests that a small group of patients who appear to have frontotemporal dementia may actually have a different and treatable condition.
The researchers say doctors should pay attention to certain warning signs. For example, patients who experience strong headaches that improve when lying down, unusual fatigue despite getting enough sleep, or who have previously been told they have Chiari malformations might need to be evaluated for a cerebrospinal fluid leak.
The discovery offers new hope for some patients and their families. Dementia diagnoses can be devastating, especially when the disease is believed to be irreversible. This research shows that in some cases, symptoms that look like dementia may actually come from a treatable physical problem.
By using more advanced imaging techniques and carefully checking for fluid leaks, doctors may be able to identify patients who could benefit from surgery and experience dramatic recovery.
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