Full Title: Cognitive impairment in fatigue and sleepiness associated conditions.
Authors: Neu D, Kajosch H, Peigneux P, Verbanck P, Linkowski P, Le Bon O.
Publication: Psychiatry Research
Publication Date: 31st December 2010
Brugmann University Hospital, Sleep Laboratory and Unit for Chronobiology U78, Department of Psychiatry, Université Libre de Bruxelles (U.L.B), Brussels, Belgium.
Although relating to very different concepts, sleepiness and fatigue are often confounded. However, both fatigue associated conditions as the chronic fatigue syndrome (CFS) and sleepiness associated conditions as the sleep apnea-hypopnea syndrome (SAHS) reported cognitive impairment with lowered 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. 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 to fatigue in CFS.