Seizures in Alzheimer's Disease

Why Seizures Are Often Mistaken for Alzheimer's Itself

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People with Alzheimer's disease are estimated to have anywhere from a two- to six-fold increase in the risk of seizures compared to the general population. Over the course of the disease, anywhere from 10 percent to 26 percent will experience some form of seizure, both apparent and non-apparent, according to research from the Baylor College School of Medicine in Texas.

While it is still unclear which mechanisms trigger the effect, there are certain characteristics that can place an individual at higher risk.

About Alzheimer’s Disease

Alzheimer’s disease is the most common form of dementia, affecting around five million Americans. It leads to the progressive and irreversible deterioration of a person’s cognitive function, manifesting with the loss of memory and the gradual decline in the ability to think or reason. It is most commonly seen in the elderly and is believed to affect anywhere from four percent to 12 percent of people over 65.

Alzheimer’s disease is caused by the gradual accumulation of a protein, known as beta-amyloid, in the brain. As these protein molecules stick together, they create lesions known as plaque which interfere with the nerve pathways central to cognitive and motor function.

Causes of Seizures in Alzheimer’s Disease

While it may seem reasonable to assume that Alzheimer’s-related seizures are directly associated with the degeneration of the brain, evidence strongly suggests that it is related more to beta-amyloid itself.

Beta-amyloid is actually a fragment of a larger compound known as amyloid precursor protein (APP). As APP is broken down, certain chemical byproducts are released into the brain which can overexcite—and effectively overload—nerve pathways. As the disease progresses, the accumulation of these byproducts can cause nerve cells to fire abnormally, triggering seizures.

The two most common types of seizure seen in persons with Alzheimer’s are:

  • Partial complex seizures, also known as focal onset impaired awareness seizures, in which a person becomes unaware of his or her surroundings and engages in unconscious actions such as fumbling, lip-smacking, wandering, or picking at clothes
  • Secondary generalized tonic-clonic seizures in which a partial seizure (affecting on side of the brain) evolves into a generalized seizure (affecting both halves), causing an all-body convulsion

Risks Factors

Outside of the biochemical triggers for seizures, there are other factors that appear to place a person at increased risk. Among them:

  • The presenilin 1 (PSEN1) and presenilin 2 (PSEN2) genetic mutations are commonly seen in people with Alzheimer’s-related seizures. The mutations are passed through families and play a key role in the production of APP.
  • People with early-onset Alzheimer's (occurring before the age of 65) are more likely to experience seizures, although the seizures will typically occur during late-stage disease.

It has also been suggested that non-convulsive seizures, including absence seizures seen in epilepsy, may be responsible for certain Alzheimer’s behaviors such as amnestic wandering (where a person wanders off with no memory or knowledge of what he or she has done).

Managing Seizures in People with Alzheimer's

Not everyone with Alzheimer’s disease will experience a seizure. Among those who do, it can be difficult to diagnose since the behaviors can sometimes mimic those of the disease itself. This is especially true with partial complex seizures during which a person can sudden "blank out" and exhibit abnormal behavior.

If a seizure has occurred or is suspected in someone with Alzheimer’s, blood and imaging test can often be used to aid in the diagnosis. In persons experiencing frequent seizures, an electroencephalogram (EEG) may help identify the seizure cause and type.

In the event of a positive diagnosis, treatment would typically involve the use of anti-epileptic medications such as Tegretol (carbamazepine), Depakote (valproic acid), Neurontin (gabapentin), and Lamictal (lamotrigine). Other types of anti-epileptic should be used with caution as they may enhance the symptoms of dementia.

If a loved one with Alzheimer's is suffering seizures, learn what to do in an emergency and ways to prevent injury if faced with a more severe, tonic-clonic event.

View Article Sources
  • Born, H. "Seizures in Alzheimer’s disease." Neuroscience. 2015; 286:251-63. DOI: 10.1016/j.neuroscience.2014.11.051.
  • Nicastro, N.; Assal, F.; and Seeck, M. "From here to epilepsy: the risk of seizure in patients with Alzheimer's disease." Epileptic Disorders. 2016; 18(1):1-12. DOI: 10.1684/epd.2016.0808.
  • Sherzai, D.; Losey, T.; Vega, S. et al. "Seizures and dementia in the elderly: Nationwide Inpatient Sample 1999-2008."& Epilepsy Behavior. 2014: 36:53-6. DOI: 10.1016/j.yebeh.2014.04.015.