Delta power in sleep in relation to neuropsychological performance in healthy subjects and schizophrenia patients.
ABSTRACT Delta power in sleep is of increasing interest because of its association with waking performance in neuropsychological tests. In schizophrenia, this link might be impaired because of a decrease in delta power in sleep and pronounced cognitive deficits. The authors analyzed delta power in sleep and neuropsychological performance in 16 patients with schizophrenia on stable medication with amisulpride and 17 healthy subjects. In healthy subjects, the authors found significant positive correlations between morning performance in declarative memory, procedural learning, and attention and delta power, especially in frontal channels. The authors interpret these results in terms of dysfunctions of thalamocortical and prefrontal networks in schizophrenia.
- SourceAvailable from: Bryce A Mander[show abstract] [hide abstract]
ABSTRACT: Whereas patients with Alzheimer's disease (AD) experience difficulties forming and retrieving memories, their memory impairments may also partially reflect an unrecognized dysfunction in sleep-dependent consolidation that normally stabilizes declarative memory storage across cortical areas. Patients with amnestic mild cognitive impairment (aMCI) exhibit circumscribed declarative memory deficits, and many eventually progress to an AD diagnosis. Whether sleep is disrupted in aMCI and whether sleep disruptions contribute to memory impairment is unknown. We measured sleep physiology and memory for two nights and found that aMCI patients had fewer stage-2 spindles than age-matched healthy adults. Furthermore, aMCI patients spent less time in slow-wave sleep and showed lower delta and theta power during sleep compared to controls. Slow-wave and theta activity during sleep appear to reflect important aspects of memory processing, as evening-to-morning change in declarative memory correlated with delta and theta power during intervening sleep in both groups. These results suggest that sleep changes in aMCI patients contribute to memory impairments by interfering with sleep-dependent memory consolidation.Journal of the International Neuropsychological Society 02/2012; 18(3):490-500. · 2.70 Impact Factor
Article: Schlaf, Plastizität und Gedächtnis[show abstract] [hide abstract]
ABSTRACT: Zahlreiche Untersuchungen – von der molekularen bis zur Verhaltensebene – zeigen, dass gesunder Schlaf neuronale Plastizität und die damit verbundene Konsolidierung deklarativen und prozeduralen Gedächtnisses begünstigt. Der vorliegende Artikel gibt einen Überblick über die aktuellen grundlagenwissenschaftlichen und klinischen Befunde. Die Ergebnisse der Schlafforschung sind dabei nicht nur für Grundlagenfragen zu Plastizität und Gedächtnisbildung interessant. Aus klinischer Perspektive können diese Erkenntnisse für gesundheitspolitisch wichtige Bereiche, wie empfehlenswertes Schlaf- und Lernverhalten, informativ sein. Weiterhin können die sich abzeichnenden Veränderungen der Gedächtnisbildung bei Patienten mit gestörtem Schlaf, wie bei primärer Insomnie oder zahlreichen psychischen Erkrankungen, zu einem vollständigeren Verständnis dieser Erkrankungen beitragen. Das langfristige Ziel ist, hieraus Ratschläge zu gesundem Verhalten und neue Behandlungsvorschläge für Patienten mit gestörtem Schlaf oder geminderter Gedächtnisfunktion abzuleiten. A compelling line of evidence – from the molecular to the behavioural level – indicates that healthy sleep facilitates neural plasticity and related declarative and procedural memory consolidation. This review provides an overview of the current basic research and clinical findings. Emerging insights into the interplay between sleep and memory have the potential to be informative for fundamental processes of brain plasticity. From a clinical perspective, new findings of disrupted sleep-related memory under conditions of disturbed sleep, such as in primary insomnia or many mental illnesses, may contribute to a more complete understanding of the disorders. The long-term goal of this research includes recommendations on healthy behavioural patterns and the development of novel interventional strategies for patients with disturbed sleep or reduced memory function.Somnologie - Schlafforschung und Schlafmedizin 04/2012; 13(1):43-51.
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ABSTRACT: Slow waves and sleep spindles, the main oscillations during non-rapid eye movement sleep, have been thought to be related to cognitive processes, and are impaired in psychotic disorders. Cognitive impairments, seen early in the course of psychotic disorders, may be related to alterations in these oscillations, but few studies have examined this relationship. Twenty seven untreated patients with a recently diagnosed psychotic disorder had polysomnographic sleep studies and neuro-cognitive testing. Reduced power in the sigma range, which reflects spindle density, was associated with impaired attention, and reasoning, but not intelligence quotient (IQ). Slow wave sleep measures were not significantly associated with any cognitive measures. Impairments in sleep spindles may be associated with cognitive deficits in the early course of psychotic disorders. These observations may help clarify neuro-biologic mechanisms of cognitive deficits in psychotic disorders such as schizophrenia.Schizophrenia Research 07/2011; 131(1-3):231-4. · 4.59 Impact Factor