Automatized online prediction of slow‐wave peaks during non‐rapid eye movement sleep in young and old individuals: Why we should not always rely on amplitude thresholds

Brain‐state‐dependent stimulation during slow‐wave sleep is a promising tool for the treatment of psychiatric and neurodegenerative diseases. A widely used slow‐wave prediction algorithm required for brain‐state‐dependent stimulation is based on a specific amplitude threshold in the electroencephalogram. However, due to decreased slow‐wave amplitudes in aging and psychiatric conditions, this approach might miss many slow‐waves because they do not fulfill the amplitude criterion. Here, we compared slow‐wave peaks predicted via an amplitude‐based versus a multidimensional approach using a topographical template of slow‐wave peaks in 21 young and 21 older healthy adults. We validate predictions against the gold‐standard of offline detected peaks. Multidimensionally predicted peaks resemble the gold‐standard regarding spatiotemporal dynamics but exhibit lower peak amplitudes. Amplitude‐based prediction, by contrast, is less sensitive, less precise and – especially in the older group – predicts peaks that differ from the gold‐standard regarding spatiotemporal dynamics. Our results suggest that amplitude‐based slow‐wave peak prediction might not always be the ideal choice. This is particularly the case in populations with reduced slow‐wave amplitudes, like older adults or psychiatric patients. We recommend the use of multidimensional prediction, especially in studies targeted at populations other than young and healthy individuals.