Relationship Between Neurological Diseases and Seizures

Epileptic seizures occur in patients with Alzheimer’s disease and Parkinson’s disease at a higher prevalence compared to healthy elderly individuals. An estimated 10% to 22% of individuals with Alzheimer’s disease will have at least one unprovoked seizure throughout the course of the disease. Additionally, the five-year epilepsy incidence rates among Medicare beneficiaries with Alzheimer’s and Parkinson’s disease are almost double the rate in those without a neurodegenerative diagnosis, with 4.5%, 4.5%, and 2.5% incidence rates in Alzheimer’s, Parkinson’s, and controls, respectively.

The prevalence of seizures and epilepsy in Alzheimer’s and Parkinson’s has resulted in research investigating the relationship between neurological diseases and seizures.

Let’s take a closer look into the connection between neurological diseases and seizures and the impact of seizures on Alzheimer’s and Parkinson’s disease patient care.

Relationship Between Neurological Diseases and Seizures

Because epileptic seizures can often be subtle, particularly with focal onset seizures, it is unclear precisely how common they are in neurological disease patients. However, the statistics, along with supporting research, suggest that both Alzheimer’s disease and Parkinson’s disease may be risk factors for seizures. 

Parkinson’s Disease as Risk Factors for Seizures and Epilepsy

A 2018 cohort study with a nested case-control analysis found that among 23,086 individuals with incident Parkinson’s disease and 92,343 individuals without Parkinson’s disease, 898 patients with incident epileptic seizures were identified. This suggests that incident Parkinson’s disease is associated with an increased risk of incident epileptic seizures.

The mechanism that triggers seizures in Parkinson’s disease is not yet clear. However, decreased cortical inhibition and increased cortical excitability have been reported in both Parkinson’s and epilepsy patients, meaning this hyperexcitable state may contribute to the onset of epileptiform activity in Parkinson’s disease patients.

Alzheimer’s Disease as Risk Factors for Seizures and Epilepsy

Typically, Alzheimer’s-related seizures occur in the later stages of Alzheimer's disease (≥6 years into the duration of the disease). Additionally, seizures are more likely to occur in those with early-onset Alzheimer’s, particularly when a familial presenilin I mutation is present. 

The precise mechanism that triggers seizures in Alzheimer’s disease patients is not yet clear. However, damage and structural changes in the brains of those with Alzheimer’s disease are likely to play a role in the increased seizure risk. Additionally, researchers have hypothesized that the buildup of amyloid and tau proteins in the brain may make neurons more excitable, as they are known to interfere with neuron-to-neuron communication. When nerve cells become hyper-excitable, they can behave uncontrollably, causing epileptic seizures.

Seizures and Alzheimer’s Disease Progression

When seizures occur in Alzheimer’s disease, they appear to be infrequent. However, seizures and epilepsy are known to affect cognitive function, causing cognitive impairment. This poses the question of how seizures affect the progression of Alzheimer’s disease.

In more advanced Alzheimer’s patients, the rate of seizures is known to be higher. This suggests that either:

1. Seizures may lead to increased rates of cognitive decline in Alzheimer’s patients, or
2. Seizures may be an epiphenomenon or a marker of more advanced Alzheimer’s stages.

Monitoring Changes in Neurocognitive Function to Inform Patient Care

There is a clear connection between neurological diseases and seizures, particularly between Alzheimer’s disease and seizures. While more research is needed to understand the true impact seizures may have on Alzheimer’s disease progression, it appears prolonged or recurrent seizures may lead to increased rates of cognitive decline.

Because of this, it is crucial to measure and monitor the neurocognitive function of patients who have experienced Alzheimer’s disease-related seizures, as this may impact patient treatment and care needs. Understanding at a detailed level how a patient’s function and ability to complete Activities of Daily Living are changing over time can help ensure patients’ care plans are effectively updated to provide the most effective care possible for each patient.