Detection of subclinical epileptiform discharges in Alzheimer's disease using long-term outpatient EEG monitoring

Christian Sandøe Musaeus*, Kristian Steen Frederiksen, Birgitte Bo Andersen, Peter Høgh, Preben Kidmose, Martin Fabricius, Melita Cacic Hribljan, Martin Christian Hemmsen, Mike Lind Rank, Gunhild Waldemar, Troels Wesenberg Kjær

*Corresponding author for this work
1 Citation (Scopus)


BACKGROUND: In patients with Alzheimer's disease (AD) without clinical seizures, up to half have epileptiform discharges on long-term in-patient electroencephalography (EEG) recordings. Long-term in-patient monitoring is obtrusive, and expensive as compared to outpatient monitoring. No studies have so far investigated if long-term outpatient EEG monitoring is able to identify epileptiform discharges in AD. Our aim is to investigate if epileptiform discharges as measured with ear-EEG are more common in patients with AD compared to healthy elderly controls (HC).

METHODS: In this longitudinal observational study, 24 patients with mild to moderate AD and 15 age-matched HC were included in the analysis. Patients with AD underwent up to three ear-EEG recordings, each lasting up to two days, within 6 months.

RESULTS: The first recording was defined as the baseline recording. At baseline, epileptiform discharges were detected in 75.0% of patients with AD and in 46.7% of HC (p-value = 0.073). The spike frequency (spikes or sharp waves/24 h) was significantly higher in patients with AD as compared to HC with a risk ratio of 2.90 (CI: 1.77-5.01, p < 0.001). Most patients with AD (91.7%) showed epileptiform discharges when combining all ear-EEG recordings.

CONCLUSIONS: Long-term ear-EEG monitoring detects epileptiform discharges in most patients with AD with a three-fold increased spike frequency compared to HC, which most likely originates from the temporal lobes. Since most patients showed epileptiform discharges with multiple recordings, elevated spike frequency should be considered a marker of hyperexcitability in AD.

Original languageEnglish
Article number106149
JournalNeurobiology of Disease
Pages (from-to)106149
Publication statusE-pub ahead of print - 15 May 2023


  • Alzheimer's disease
  • Device
  • Ear-EEG
  • EEG
  • Long-term EEG
  • Subclinical epileptiform discharges
  • Wearable


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