ABNORMAL SPECTRAL EEG IN AMYOTROPHIC LATERAL SCLEROSIS IS ASSOCIATED WITH DISTINCT NEUROBIOLOGICAL PROFILES

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease that primarily affects motor neurons. As ALS progresses, it also impacts extra-motor regions, leading to cognitive and behavioural symptoms. The causes of the disease remain unknown, and it is unclear why certain neuronal populations are more vulnerable while others are spared. Evidence of impaired neuronal activity in the form of EEG abnormalities correlates with structural changes in ALS, but the neurobiological identity of the neuronal populations affected remains poorly understood.
To characterise the affected neuronal populations in terms of their molecular and cytoarchitectural features, we have correlated spectral changes in people with ALS (pwALS) with the spatial distribution of neurobiological factors. High-density EEG recordings from resting-state eyes-open of pwALS (n=121) and Healthy Controls (HC; n=120), as well as source-localization analysis were used to estimate differences in the oscillatory and aperiodic activity of the power spectrum. The associations of spectral differences in pwALS with normative brain maps of molecular and micro-structural signatures were studied using multivariate partial least squares.
We identified an overall significant decrease in alpha and beta power in pwALS over frontal and parietal areas, respectively, with a concurrent decrease in the aperiodic exponent outside of somatosensory areas. Significant correlations were found between Latent Variables in the spectral domain and those in the neurobiological maps, highlighting unique characteristics of the affected neuronal populations. More importantly, these findings provide evidence linking spectral changes in EEG with distinct underlying biological alterations.