title: Cognitive impairment and EEG background activity in adults with Down's syndrome: a topographic study.
abstract: OBJECTIVE
  Studies correlating electroencephalographic (EEG) data and cognitive performance in Down's syndrome (DS) showed conflicting results. The aims of this study were to investigate the sources of EEG rhythms in adults with DS at three dimensional representation of current source density (CSD) using exact/standard Low Resolution Electromagnetic Tomography (e/sLORETA), and their correlation with cognitive performance.
  
  
  METHODS
  Twenty-five adults with DS underwent a neuropsychological battery and 5 min of resting, eye-closed 29-channel EEG were recorded. After e/sLORETA analysis, data were compared with those from age and gender-matching control subjects as following: absolute and relative power in delta (1-3 Hz), theta (4-7 Hz), alpha1 (8-9 Hz), alpha2 (10-12 Hz), beta1 (13-18 Hz), beta2 (19-21 Hz), beta3 (22-30 Hz); alpha and theta bands adjusted to individual alpha peak frequency (IAF). Current source activities in DS group in regions showing significant differences compared with controls underwent correlation analysis with psychometric scores.
  
  
  RESULTS
  In DS, IAF was shifted to lower frequencies and correlated positively with Wechsler Adult Intelligence Scale and Mini-Mental State examination. Compared with controls, DS showed increased CSD in: theta, alpha-1, and beta1 classical bands and in IAF-adjusted bands, while relative alpha2 was decreased. A negative correlation between cognitive performance and theta/alpha CSD in the right frontal lobe and right posterior cingulate cortex was found. The relative alpha2 correlated positively with cognitive tests.
  
  
  CONCLUSIONS
  Increased CSD in DS, correlating with cognitive performance, for both slow and fast rhythms suggests involving of cortical and subcortical mechanisms. LORETA might be useful for objective measure of cognitive decline in DS.
authors.affiliation: Department of Neurology, Clinical Neurophysiology, Neurorehabilitation, Institute of Experimental Neurology-INSPE, IRCCS University Hospital, San Raffaele, Via Olgettina 60, Milan, Italy.
authors.forename: Svetla
authors.initials: S
authors.lastname: Velikova
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Magnani
authors.forename: Claudia
authors.initials: C
authors.lastname: Arcari
authors.forename: Monica
authors.initials: M
authors.lastname: Falautano
authors.forename: Massimo
authors.initials: M
authors.lastname: Franceschi
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Comi
authors.forename: Letizia
authors.initials: L
authors.lastname: Leocani
mesh_terms: D000328:Adult; D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003072:Cognition Disorders / Q000209:etiology / Q000503:physiopathology*; D004314:Down Syndrome / Q000150:complications / Q000503:physiopathology*; D004569:Electroencephalography; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests