Silent Seizures: A Surprising Phenomenon in Alzheimer's Disease

People often associate seizures with convulsions and a complete loss of bodily control. However, there’s another type of seizure that happens deep within the brain and might be difficult to notice. Symptoms of silent seizures include a momentary loss of responsiveness, a blank stare, or fluttering eyelids. Recently, researchers have found that these seizures affect people with non-genetic Alzheimer’s disease and might have something to do with their memory loss.

What Is a Silent Seizure? 

A silent seizure, also known as an absence seizure, is a brief period of abnormal neurological signals that causes someone to lose focus for about 10-20 seconds, earning this condition its quiet name. Unlike other seizures, electroencephalograms (EEGs) don’t detect silent ones because they happen so deep in the brain.

The Connection Between Alzheimer's Disease and Silent Seizures 

Researchers at Baylor College of Medicine found that people had increased levels of a protein called deltaFosB in their hippocampus for about two weeks after a silent seizure. This protein is responsible for regulating other proteins, and researchers found that it suppressed the creation of another protein called calbindin. 

Calbindin is necessary for the creation of new memories, which is one of the things people with Alzheimer’s disease struggle with the most. The low level of calbindin means that people will have a harder time making and keeping memories. Researchers looked into supplementing calbindin levels in mice who had silent seizures and found that this practice can improve memory in animal models. 

Understanding Neuron Creation and Silent Seizures  

Neurons are responsible for transmitting information throughout the body. These nerve cells can signal your heart to beat, muscles to move, and lungs to take in air, among other bodily functions. In a process called neurogenesis, healthy people use neural stem cells to create new neurons in the brain. In people with Alzheimer’s disease, the abnormal brain activity that causes a silent seizure also causes neurogenesis to start. 

Unfortunately, the number of stem cells is finite, and the more seizures someone has, the quicker they will run out of stem cells to fuel neurogenesis. Eventually, their brain will be unable to support neurogenesis, which can lead to further cognitive decline.

One study found that giving anti-seizure medication to mice with Alzheimer’s disease resulted in a more normal neurogenesis process, meaning the brain would use neural stem cells more efficiently. These animal studies have given researchers the opportunity to speculate about how certain treatments can work in humans.

If a loved one begins exhibiting signs of Alzheimer’s disease, schedule an appointment with a St. Luke’s Health neurologist. Ranked the top neurology and neurosurgery program in Houston by U.S. News & World Report, Baylor St. Luke’s Medical Center is renowned for using breakthrough research and a collaborative approach that resonates throughout the St. Luke’s Health network of care. With some of the best brains in neuroscience, our team manages patient care today while developing new treatments for tomorrow.

Sources: 
Baylor College of Medicine | ‘Silent seizures’ found in patients with Alzheimer’s disease
Baylor College of Medicine | Mechanism explains how seizures may lead to memory loss
Baylor College of Medicine | Connecting seizures, neurogenesis and cognitive functions in Alzheimer’s disease
Medical News Today | All you need to know about neurons
Epilepsy Foundation | Absence Seizures
AAAS | Neurogenesis takes a hit in Alzheimer’s disease