title: Cognitive impairment in fatigue and sleepiness associated conditions.
abstract: Although relating to very different concepts, sleepiness and fatigue are often confounded. However, both fatigue-associated conditions such as the chronic fatigue syndrome (CFS) and sleepiness-associated conditions such as the sleep apnea-hypopnea syndrome (SAHS) are associated with cognitive impairment with impaired attention, concentration and memory performances. Fifteen pure CFS patients, without primary sleep disorders or clinically relevant sleepiness, were compared to 15 untreated SAHS patients, without clinically relevant fatigue, and to 16 healthy controls of similar age. The auditory verbal learning test (AVLT), digit span, digit symbol and finger tapping test (FTT) were used as cognitive and behavioural measures. In addition we assessed daytime EEG spectral power and P300 evoked potentials. With exception for the digit span, all tests showed lower performances in patient groups. Recall on the AVLT did not differ between the two patient groups, but the digit and symbol spans showed more severe impairment in SAHS patients. Psychomotor performance on the FTT presented with slower hit rates in SAHS than in CFS. EEG theta power was highest in CFS patients. P300 latencies and amplitudes did not differ between groups. Fatigue- and sleepiness-associated conditions can both present with significant and objective impairment of cognitive functioning and behavioural motor performance. In our sample cognitive impairment and psychomotor performance were worse when associated to sleepiness in SAHS than with fatigue in CFS.
authors.affiliation: Brugmann University Hospital, Sleep Laboratory and Unit for Chronobiology U78, Department of Psychiatry, Université Libre de Bruxelles (U.L.B), Brussels, Belgium. daniel.neu@chu-brugmann.be
authors.forename: Daniel
authors.initials: D
authors.lastname: Neu
authors.forename: Hendrik
authors.initials: H
authors.lastname: Kajosch
authors.forename: Philippe
authors.initials: P
authors.lastname: Peigneux
authors.forename: Paul
authors.initials: P
authors.lastname: Verbanck
authors.forename: Paul
authors.initials: P
authors.lastname: Linkowski
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Bon
mesh_terms: D000328:Adult; D000342:Affective Symptoms / Q000175:diagnosis / Q000209:etiology; D003072:Cognition Disorders / Q000175:diagnosis / Q000209:etiology*; D004569:Electroencephalography / Q000379:methods; D018913:Event-Related Potentials, P300 / Q000502:physiology; D005221:Fatigue / Q000150:complications*; D005260:Female; D007839:Functional Laterality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D017286:Polysomnography; D011597:Psychomotor Performance / Q000502:physiology; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012893:Sleep Wake Disorders / Q000150:complications* / Q000175:diagnosis; D013057:Spectrum Analysis; D013223:Statistics as Topic; D014706:Verbal Learning / Q000502:physiology