Background Patients with Alzheimer’s disease (AD) are more prone to seizures and myoclonus, but relative risk of these symptoms among other dementia types is unknown. Objective To determine incidence of seizures and myoclonus in the three most common neurodegenerative dementias: AD, dementia with Lewy bodies (DLB), and frontotemporal dementia (FTD). Methods Our institution’s medical records were reviewed for new-onset unprovoked seizures and myoclonus in patients meeting criteria for AD (n=1,320), DLB (n=178), and FTD (n=348). Cumulative probabilities of developing seizures and myoclonus were compared between diagnostic groups, whereas age-stratified incidence rates were determined relative to control populations. Results The cumulative probability of developing seizures after disease onset was 11.5% overall, highest in AD (13.4%) and DLB (14.7%) and lowest in FTD (3.0%). The cumulative probability of developing myoclonus was 42.1% overall, highest in DLB (58.1%). The seizure incidence rates, relative to control populations, were nearly 10 fold in AD and DLB, and 6 fold in FTD. Relative seizure rates increased with earlier age-at-onset in AD (age <50, 127 fold; 50–69, 21 fold; 70+, 2 fold) and FTD (age <50, 53 fold; 50–69, 9 fold), and relative myoclonus rates increased with earlier age-at-onset in all groups. Seizures began an average of 3.9 years after the onset of cognitive or motor decline, and myoclonus began 5.4 years after onset. Conclusions Seizures and myoclonus occur with greater incidence in patients with AD, DLB, and FTD than in the general population, but rates vary with diagnosis, suggesting varied pathomechanisms of network hyperexcitability. Patients often experience these symptoms early in disease, suggesting hyperexcitability could be an important target for interventions.

We report on a test to assess the dynamic brain function at high temporal resolution using magnetoencephalography (MEG) for 45-60 s. After fitting an autoregressive integrative moving average (ARIMA) model and taking the stationary residuals, all pairwise, zero-lag, partial cross-correlations P CC 0 ij and their z-transforms z 0 ij between i and j sensors were calculated, providing estimates of the strength and sign (positive, negative) of direct synchronous coupling at 1 ms temporal resolution. We found that subsets of z 0 ij successfully classified individual subjects to their respective groups (multiple sclerosis, Alzheimer's disease, schizophrenia, Sjögren's syndrome, chronic alcoholism, facial pain, healthy controls) and gave excellent external cross-validation results..