COMMENTARY

Double Trouble: Seizures and Alzheimer Disease

Epilepsy Notes

Andrew N. Wilner, MD

Disclosures

October 28, 2013

Seizures in Alzheimer Disease: A Retrospective Study

Unprovoked seizures develop in 10%-22% of people with Alzheimer disease, a disorder that affects more than 5 million Americans.[1] Consequently, as many as 1 million people with Alzheimer disease in the United States may develop seizures. The likelihood of seizures increases in familial and early-onset cases of Alzheimer disease.[2] After cerebrovascular disease and brain tumors, Alzheimer disease and other dementias are the most common etiologies of seizures in elderly persons.[3]

A recent retrospective study by Vossel and colleagues[2] covering a 5-year period (2007-2012) reported on 12 patients with amnestic mild cognitive impairment (aMCI) and 35 patients with Alzheimer disease, all of whom had epilepsy. Another 7 patients with Alzheimer disease plus subclinical epileptiform activity were included. Patients with epilepsy beginning before age 30 years or known etiologies of seizures (eg, subdural hematoma, stroke) that were presumably unrelated to the development of aMCI or Alzheimer disease were excluded.

Study findings. Patients with aMCI and epilepsy presented with cognitive decline 6.8 years earlier (at age 64.3 years vs 71.1 years) than those with aMCI without epilepsy (P=.02). Those with Alzheimer disease and epilepsy presented with cognitive decline 5.5 years earlier (at age 64.8 years vs 70.3 years) than those with Alzheimer disease without epilepsy (P=.001). Patients with Alzheimer disease and subclinical epileptiform activity had an early onset of cognitive decline (at age 58.9 years).

Seizure characteristics. The most common seizure type was complex partial seizures (n = 22), followed by generalized (n = 17) and partial seizures (n = 8). Overall, 55% of the patients had only nonconvulsive seizures. Symptoms included amnestic spells, aphasia, déjà vu, jamais vu, psychic and sensory phenomena, and speech/behavior arrest. Ictal bradycardia occurring in 5 patients required a pacemaker. Seizures tended to occur early in the disease. Epileptic foci were most often unilateral and temporal. Lamotrigine and levetiracetam were more likely than phenytoin or valproic acid to render patients seizure-free.

EEG investigation. Serial or prolonged electroencephalographic (EEG) monitoring may confirm suspected seizure activity that is missed by a routine 20-minute EEG. In this study, serial EEG or long-term monitoring detected 62.5% of patients ultimately diagnosed with epilepsy vs only 29.2% of cases that were detected by a routine EEG.

Antiepileptic drug treatment. Seizure control in study patients was more successful with lamotrigine or levetiracetam than phenytoin, which was significantly less well tolerated and less effective. Although phenytoin is a commonly used antiepileptic drug, its first-order pharmacokinetics and susceptibility to drug/drug interactions are problematic in elderly patients, who often take multiple medications for a variety of comorbid conditions.

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