Silent seizures and Alzheimer's disease

Scientists say mice genetically altered to develop an Alzheimer's-like illness undergo "silent" brain seizures.

According to researchers at the Baylor College of Medicine, the seizures may explain why some people with advanced Alzheimer's have "spells" of increased confusion. The seizures observed in the mice would not be recognizable in the same way a convulsion or epileptic seizure can be noticed.

These subtle seizures may be linked to cellular changes caused by high brain levels of the Alzheimer's-linked amyloid beta protein.

Understanding the process behind the seizures may lead to treatments that can prevent or even reverse the progression of the disease, the researchers said in the September issue ofNeuron.
The research team recorded electrical brain waves in the hippocampus, deep in the mice's brains. The hippocampus is a brain area associated with memory.

"This discovery has helped identify a new and potentially reversible neural mechanism that can explain the episodes of sudden severe confusion found in cases of advanced Alzheimer's disease," Dr. Jeffrey Noebels, director of the Bluebird Circle Developmental Neurogenetics Laboratory at Baylor College of Medicine, said in a prepared statement. "The cellular changes that give rise to this hyperexcitability appear slowly as the disease progresses, and, at a certain point, the brain networks actually become hyperexcitable, despite the loss of synapses and brain cells in this brain region. Further study may point to early treatment that might prevent these electrical brain spells, as well as slow down the progression of this debilitating disease."

Prior to this research, spells of increased confusion were thought to be a result of degenerating nerve cells. According to the researchers, the study indicated that they may result from excess amyloid beta and could signal future cognitive failure. Amyloid beta is a toxic protein fragment found in the brains of people with Alzheimer's disease and similar disorders.

Alzheimer's disease is the most common form of dementia. More than 5 million Americans are living with the disease, which is characterized by a progressive loss of memory and cognitive function. There is no known cure for the disease.

More information

For more about Alzheimer's disease, visit the Alzheimer's Association.

SOURCE: Baylor College of Medicine, news release, Sept. 5, 2007