AUTHOR=Fernández Alberto , Ramírez-Toraño Federico , Bruña Ricardo , Zuluaga Pilar , Esteba-Castillo Susanna , Abásolo Daniel , Moldenhauer Fernando , Shumbayawonda Elizabeth , Maestú Fernando , García-Alba Javier 

TITLE=Brain signal complexity in adults with Down syndrome: Potential application in the detection of mild cognitive impairment

JOURNAL=Frontiers in Aging Neuroscience

VOLUME=Volume 14 - 2022

YEAR=2022

URL=https://www.frontiersin.org/journals/aging-neuroscience/articles/10.3389/fnagi.2022.988540

DOI=10.3389/fnagi.2022.988540

ISSN=1663-4365

ABSTRACT=BBackground: Down syndrome (DS) is considered the most frequent cause of early-onset Alzheimer’s disease (AD), and the typical pathophysiological signs are present in almost all individuals with DS by the age of 40. Despite of this evidence, the investigation on the pre-dementia stages in DS is scarce. In the present study we analyzed the complexity of brain oscillatory patterns and neuropsychological performance for the characterization of mild cognitive impairment (MCI) in DS. 
Methods: Lempel-Ziv complexity (LZC) values from resting-state magnetoencephalography recordings and the neuropsychological performance in 28 patients with DS [control DS group (CN-DS) (n=14), MCI group (MCI-DS) (n=14)] and 14 subjects with typical neurodevelopment (CN-no-DS) were analyzed.
Results: LZC was lowest in the frontal region within the MCI-DS group, while the CN-DS group showed reduced values in parietal areas when compared with the CN-no-DS group. Also, the CN-no-DS group exhibited the expected pattern of significant increase of LZC as a function of age, while MCI-DS cases showed a decrease. The combination of reduced LZC values and a divergent trajectory of complexity evolution with age, allowed the discrimination of CN-DS vs. MCI-DS patients with a 92.9% of sensitivity and 85.7% of specificity. Finally, a pattern of mnestic and praxic impairment was significantly  associated in MCI-DS cases with the significant reduction of LZC values in frontal and parietal regions (p=0.01). 
Conclusions: Brain signal complexity measured with LZC is reduced in DS and its development with age is also disrupted. The combination of both features might assist in the detection of MCI within this population.