An emerging body of neurofeedback research for improving cognitive function has demonstrated evidence for such conditions as stroke (Kober et.al., 2015; Kober et.al., 2017) and multiple sclerosis (Kober et.al., 2019; Keune et.al., 2019), with a particular focus on Alzheimer’s disease (AD), the most common form of dementia, as well as mild cognitive impairment (MCI), a pre-dementia condition (Petersen, 2004; Albert MS et.al., 2019), in the hopes of delaying the insidious cognitive decline and dementia onset.
The Neural Imbalance:
Memory impairment is the hallmark of early AD and its precursor amnestic MCI (aMCI); other cognitive domains may also be impaired. In the EEG, MCI and AD are generally characterized by an increase in slow frequencies (delta: 2-4 Hz; theta: 4-8 Hz) and a decrease in faster frequencies (alpha: 8-12 Hz; beta: 13-20 Hz) [Vigil J. Tataryn et al., 2017]. These EEG features have been linked to symptoms such as poor cognitive performance (Klimesch, 1999), atrophy of the thalamus, hippocampus, and basal ganglia (Moretti et al., 2012; Wolf, 2004), and the formation of amyloid-beta plaques (Sharma & Nadkarni, 2020).
Neurofeedback protocols in healthy and mildly impaired older adults have mainly targeted enhancing alpha, inhibiting theta, or increasing the alpha-theta ratio at posterior sites (Chapin & Russell-Chapin, 2013). Some have used attention training to enhance sensorimotor rhythm (SMR; low beta) or reduce theta-beta ratio (TBR) at central sites (Jiang et al., 2017; Jang et al., 2019), given that enhancing attention improves encoding, maintenance and retrieval of items held in working memory.
Several recent studies have reported better memory performance in MCI following neurofeedback. Lavy and colleagues (Lavy Y et al., 2019) found improved verbal memory after ten 30-minute sessions in which MCI participants enhanced individual central-parietal upper-alpha; improvement was maintained at 30-day follow-up.
Jirayucharoensak and colleagues (Jirayucharoensak et al., 2019) used alpha- and beta-enhancement neurofeedback (twenty 30-minute sessions) as an add-on to usual care in healthy or aMCI women and found improved rapid visual processing and spatial working memory.
In AD, studies using individualized neurofeedback protocols have reported improved cognitive screener performance (Surmeli et al., 2015) and memory/executive function as compared with wait-list control (Berman et al., 2015).
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