Abnormal electrical activity in the brain of people with Alzheimer's leads to epileptic seizures

Alzheimer's disease causes death of neurons, and researchers hypothesize this may contribute to abnormal electrical activity in the brain that leads to epileptic seizures.

There appears to be a mechanism at work that puts people living with dementia at higher risk and recurrence of all types of seizures. While we continue our push to find treatments and preventions for Alzheimer's and other dementias, doctors should be aware of how common seizures are in this population to better monitor and treat these individuals."

Maria C. Carrillo, Ph.D., chief science officer, Alzheimer's Association

"At the research level, we need additional studies to understand more about the shared mechanisms between epilepsy and Alzheimer's that might help us better understand the impact seizures have on the brain in order to better treat both seizures and cognitive decline," Carrillo added.

Seizures can be a symptom of epilepsy, but not all people who experience seizures have epilepsy. Seizures indicate a disruption of brain function even though the person may not always lose consciousness. Epilepsy is a nervous system disorder in which brain electrical activity becomes abnormal, causing seizures plus unusual behavior, sensations, and sometimes loss of awareness.

People with dementia may experience many types of seizures

Ruby Castilla-Puentes, MD, DrPH, MBA, director, clinical research, neuroscience, Janssen Pharmaceuticals and colleagues Miguel Habeych, MD, MPH at the University of Cincinnati analyzed a large U.S. national managed care database including more than 2.8 million individuals with and without dementia, age 60 and older. In the database, 79,561 persons (2.8%) had a dementia diagnosis. Of that group, 56% were women. The study population was followed from 2005 to 2014.

Study participants with a dementia diagnosis were found to have higher risk of new onset or first-time seizures. Researchers also found that participants with dementia experienced a variety of seizure types. These included:

• 6.5 times increase risk for seizures where the origin could not be determined.
• 6 times elevated risk for partial seizures.
• 5.2 times higher risk for generalized and undifferentiated epilepsy.
• 4.75 times increased risk for generalized seizures and partial epilepsy.

"There may be many reasons for these higher rates, including the medications used to treat dementia, other medical conditions associated with both seizures and dementia, or a combination of factors," said Castilla-Puentes. "More research is needed to answer that question."

"For right now, these findings reinforce the need for clinicians to be aware of and monitor for seizures to ensure that their patients with dementia receive appropriate treatment," Castilla-Puentes added.

High recurrence rates and potential negative consequences of epilepsy in dementia

In another study reported at AAIC 2019, analysis of data from the National Alzheimer's Coordinating Center, comprising 20,745 individuals at 34 centers between 2005 and 2016, found that prevalence of active seizures was higher in persons with Alzheimer's than in persons without the disease (1.51% vs. 0.35%). And persons with Alzheimer's disease were also twice as likely to have had a previous seizure (3.14% vs. 1.57%).

The researchers found that the longer the individuals had been living with Alzheimer's, the higher the risk for having a seizure (1.5% at 4.8 years up to 5.4% at 11 years). More than two-thirds (70.4%) of persons with Alzheimer's in the study who experienced a seizure had a second seizure in the next seven-and-a-half months. History of a seizure was associated with younger age of onset of cognitive symptoms (seizures vs. no seizures; 64.7 vs. 70.4 years), more severe memory problems and impaired everyday life skills.

"People with Alzheimer's are at increased risk for seizures, in particular in more advanced stages of the disease, and they have an exceptionally high recurrence risk," said Jonathan Vöglein, M.D., Ludwig-Maximilians-Universität München and the German Center for Neurodegenerative Diseases, Munich, Germany. "The high recurrence risk and potentially negative consequences of seizures suggest that individuals with Alzheimer's should be treated with anti-epileptic drugs after their first seizure."

"It's clearly important to focus on seizures in people with Alzheimer's so that their treatment may be improved. This includes development of anti-epileptic drugs specifically for prevention of seizures in persons living with Alzheimer's," Vöglein added.