SUMMAR Y The level of procedural skills improves in normal individuals when the acquisition is followed by a period of sleep rather than wake. If sleep plays an important role in the consolidation process the advantage it provides should be reduced or delayed when its organization is altered, as in patients with chronic sleep disorders. To test this prediction in patients with narcolepsy-cataplexy (NC), who usually have a more fragmented organization of sleep than normals, we compared the initial, intermediate and delayed level of consolidation of visual skills. Twenty-two drug-naive NC patients and 22 individually-matched controls underwent training at a texture discrimination task (TDT) and were re-tested on the next morning (after a night spent in laboratory with polysomnography) and after another six nights (spent at home). TDT performance was worse in patients than controls at training and at both retrieval sessions and the time course of consolidation was different in NC patients (who improved mainly from next-day to 7th-day retrieval session) compared with controls. Moreover, the lessimproving patients at next-day retrieval had a wider disorganization of sleep, probably because of an episode of rapid eye movement (REM) sleep at sleep onset REM, on post-training night more frequently than more-improving patients. These findings suggest that the time course of the consolidation process of procedural skills may be widely influenced by the characteristics of sleep organization (varying night-by-night much more in NC patients than controls) during post-training night.
It is well-known that liver cirrhosis is frequently accompanied by a wide range of neuropsychiatric abnormalities, including general and specific cognitive impairment. The aim of this study was to investigate which cognitive functions are selectively compromised in Hepatic Encephalopathy (HE) and to clarify the relationship between clinically overt or nonovert HE and the different forms and degrees of decay in cognitive deficits. Twenty-two patients without overt HE and 12 patients who showed overt HE at the first level of severity, along with matched control subjects, were compared in several cognitive domains. The results showed significant differences in some measures of attention between patients with minimal HE (mHE) and patients with overt HE. There were also notable differences in verbal short-term memory between patients with mHE and healthy subjects. Thus, we can hypothesize that there is a linear diminution in short-term memory and attentional performance starting from healthy patients, moving toward patients with mHE, and finally progressing toward patients with the first grade of overt HE. There are two types of diminution that we noted: between patients with mHE and the overt form, the decline in the attentional domain was more evident, while between healthy subjects and mHE patients, short-term memory showed a more evident decline.
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