  Alzheimer's disease (AD) is one of the most common neurodegenerative
diseases, with around 50 million patients worldwide. Accessible and
non-invasive methods of diagnosing and characterising AD are therefore urgently
required. Electroencephalography (EEG) fulfils these criteria and is often used
when studying AD. Several features derived from EEG were shown to predict AD
with high accuracy, e.g. signal complexity and synchronisation. However, the
dynamics of how the brain transitions between stable states have not been
properly studied in the case of AD and EEG data. Energy landscape analysis is a
method that can be used to quantify these dynamics. This work presents the
first application of this method to both AD and EEG. Energy landscape assigns
energy value to each possible state, i.e. pattern of activations across brain
regions. The energy is inversely proportional to the probability of occurrence.
By studying the features of energy landscapes of 20 AD patients and 20 healthy
age-matched counterparts, significant differences were found. The dynamics of
AD patients' brain networks were shown to be more constrained - with more local
minima, less variation in basin size, and smaller basins. We show that energy
landscapes can predict AD with high accuracy, performing significantly better
than baseline models.
