Power Spectra and Fractal Complexity in Neurocognitive Disorders: A QEEG Study Protocol

Synaptic dysfunction and the resulting disruption of neuronal networks are key pathological processes in neurocognitive disorders., such as Alzheimer's Disease (AD). Quantitative EEG (QEEG) provides a non-invasive., cost-effective approach for assessing these changes. This study protocol outlines the methodology used to evaluate the efficacy of two QEEG metrics (power spectral density – PSD – and Higuchi's fractal dimension – HFD) in discriminating individuals with “pure” AD from those affected by AD combined with additive proteinopathies. While PSD assumes sustained sinusoidal oscillations., increasing evidence highlights the intermittent., non-sinusoidal nature of brain rhythms., emphasizing the need for complementary non-linear approaches. The study protocol includes rigorous EEG pre-processing and analysis strategies to extract both linear and non-linear features of brain activity. Preliminary results from a pilot cohort show that both PSD and HFD detect significant changes in synaptic activity associated with neurodegeneration., with HFD demonstrating greater sensitivity. These findings support the potential of fractal dimension analysis to enhance the neurophysiological characterization of complex neuropathological profiles.