Alzheimer’s disease (AD) is a progressive neurodegenerative disease leading to a disruption of normal brain oscillations (Coben et al., 1985; Jeong, 2004; Musaeus et al., 2018a). The disruption of brain oscillations has even been seen in the prodromal phase of a disease known as mild cognitive impairment (MCI) (Musaeus et al., 2018b). MCI refers to mild objective cognitive deficits and is associated with the later development of AD (Petersen et al., 1999; Petersen, 2004), but not all patients with mild MCI convert to AD (Petersen, 2004). Attempts have been made to use electroencephalography (EEG) as a marker of whether a patient with MCI will progress (pMCI) or remain stable (sMCI) using spectral power (Jelic et al., 2000; Poil et al., 2013; Musaeus et al., 2018b). However, brain oscillations of different frequencies are not isolated entities, and the coupling between different frequency bands may further our understanding of the pathophysiological processes (Buzsáki and Watson, 2012). This coupling between different frequencies, a phenomenon called cross-frequency coupling (CFC) (Canolty and Knight, 2010), has shown a variety of functional roles, including memory in both rodents and humans.
