title: Quantitative spectral analysis of EEG in psychiatry revisited: drawing signs out of numbers in a clinical setting.
abstract: OBJECTIVE
  To evaluate the incidence, sensitivity and specificity of abnormal quantitative EEG (QEEG) measures in normal subjects and patients with mental disorders.
  
  
  METHODS
  Normalized QEEG measures were blindly assessed in 67 normal human beings and 340 psychiatric patients. QEEG results were correlated to subject condition or diagnosis and magnetic resonance imaging (MRI) findings.
  
  
  RESULTS
  QEEG was abnormal in 83% of patients, and 12% of normal subjects. The most frequent abnormality was a decrease in slow (delta and/or theta) bands, either alone, with beta increase, or with alpha decrease, followed by increase in beta band. No normal subject showed delta and/or theta decrease. Slow band decrease was more frequent in depression and mental disorders due to general medical condition, alcohol and drug dependence. However, no pattern was specific of any entity, and patients within the same diagnostic may present different patterns. Delta-theta decrease was correlated with cortical atrophy as seen in MRI. Beta increase was correlated with psychoactive medication. No association was found between any other QEEG pattern and MRI abnormalities, or medication.
  
  
  CONCLUSIONS
  Decrease in the delta and theta bands of the QEEG can be regarded as a specific sign of brain dysfunction, and is correlated with cortical atrophy. However, this sign, as other QEEG abnormal patterns, can be found in many different disorders and none of them can be considered as pathognomonic of any specific disorder.
  
  
  CONCLUSIONS
  This work attempted to circumvent the alleged lack of Class I evidence of QEEG utility in the study of psychiatric patients by means of a prospective, blinded study, searching for specific signs of physiopathology in individual patients.
authors.affiliation: Department of Electrophysiology, Hospital Psiquiátrico San Juan de Dios, Urb. Campo Claro, Los Curos, Mérida 5101, Venezuela. coutinpe@hotmail.com
authors.forename: P
authors.initials: P
authors.lastname: Coutin-Churchman
authors.forename: Y
authors.initials: Y
authors.lastname: Añez
authors.forename: M
authors.initials: M
authors.lastname: Uzcátegui
authors.forename: L
authors.initials: L
authors.lastname: Alvarez
authors.forename: F
authors.initials: F
authors.lastname: Vergara
authors.forename: L
authors.initials: L
authors.lastname: Mendez
authors.forename: R
authors.initials: R
authors.lastname: Fleitas
mesh_terms: D000293:Adolescent; D000328:Adult; D001284:Atrophy; D001927:Brain Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D002540:Cerebral Cortex / Q000473:pathology; D004569:Electroencephalography / Q000379:methods*; D005260:Female; D006801:Humans; D015994:Incidence; D008279:Magnetic Resonance Imaging; D008297:Male; D001523:Mental Disorders / Q000175:diagnosis* / Q000453:epidemiology*; D008875:Middle Aged; D012680:Sensitivity and Specificity