Sleep-Wake Cycle Dysfunction in the TgCRND8 Mouse Model of Alzheimer's Disease: From Early to Advanced Pathological Stages.

In addition to cognitive decline, individuals affected by Alzheimer's disease (AD) can experience important neuropsychiatric symptoms including sleep disturbances. We characterized the sleep-wake cycle in the TgCRND8 mouse model of AD, which overexpresses a mutant human form of amyloid precursor protein resulting in high levels of β-amyloid and plaque formation by 3 months of age. Polysomnographic recordings in freely-moving mice were conducted to study sleep-wake cycle architecture at 3, 7 and 11 months of age and corresponding levels of β-amyloid in brain regions regulating sleep-wake states were measured. At all ages, TgCRND8 mice showed increased wakefulness and reduced non-rapid eye movement (NREM) sleep during the resting and active phases. Increased wakefulness in TgCRND8 mice was accompanied by a shift in the waking power spectrum towards fast frequency oscillations in the beta (14-20 Hz) and low gamma range (20-50 Hz). Given the phenotype of hyperarousal observed in TgCRND8 mice, the role of noradrenergic transmission in the promotion of arousal, and previous work reporting an early disruption of the noradrenergic system in TgCRND8, we tested the effects of the alpha-1-adrenoreceptor antagonist, prazosin, on sleep-wake patterns in TgCRND8 and non-transgenic (NTg) mice. We found that a lower dose (2 mg/kg) of prazosin increased NREM sleep in NTg but not in TgCRND8 mice, whereas a higher dose (5 mg/kg) increased NREM sleep in both genotypes, suggesting altered sensitivity to noradrenergic blockade in TgCRND8 mice. Collectively our results demonstrate that amyloidosis in TgCRND8 mice is associated with sleep-wake cycle dysfunction, characterized by hyperarousal, validating this model as a tool towards understanding the relationship between β-amyloid overproduction and disrupted sleep-wake patterns in AD.

translin Is Required for Metabolic Regulation of Sleep

Dysregulation of sleep or feeding has enormous health consequences. In humans, acute sleep loss is associated with increased appetite and insulin insensitivity, while chronically sleep-deprived individuals are more likely to develop obesity, metabolic syndrome, type II diabetes, and cardiovascular disease. Conversely, metabolic state potently modulates sleep and circadian behavior; yet, the molecular basis for sleep-metabolism interactions remains poorly understood. Here, we describe the identification of translin (trsn), a highly conserved RNA/DNA binding protein, as essential for starvation-induced sleep suppression. Strikingly, trsn does not appear to regulate energy stores, free glucose levels, or feeding behavior suggesting the sleep phenotype of trsn mutant flies is not a consequence of general metabolic dysfunction or blunted response to starvation. While broadly expressed in all neurons, trsn is transcriptionally upregulated in the heads of flies in response to starvation. Spatially restricted rescue or targeted knockdown localizes trsn function to neurons that produce the tachykinin family neuropeptide Leucokinin. Manipulation of neural activity in Leucokinin neurons revealed these neurons to be required for starvation-induced sleep suppression. Taken together, these findings establish trsn as an essential integrator of sleep and metabolic state, with implications for understanding the neural mechanism underlying sleep disruption in response to environmental perturbation.

Implicit memory for the content but not the speaker of sleep-played messages

We presented 28 sentences uttered by 28 unfamiliar speakers to sleeping participants to investigate whether humans can encode new verbal messages, learn voices of unfamiliar speakers, and form associations between speakers and messages during EEG-defined deep sleep. After waking, participants performed three tests which assessed the unconscious recognition of sleep-played speakers, messages, and speaker-message associations. Recognition performance in all tests was at chance level. However, response latencies revealed implicit memory for sleep-played messages but neither for speakers nor for speaker-message combinations. Only participants with excellent implicit memory for sleep-played messages also displayed implicit memory for speakers but not speaker-message associations. Hence, deep sleep allows for the semantic encoding of novel verbal messages.

Post-H1N1 Flu Vaccination Narcolepsy in Switzerland: A Retrospective Survey in the 30 Sleep-Certified Swiss Centers

Narcolepsy-cataplexy is a sleep-wake disorder and suggested to be immune-mediated, involving genetic and environmental factors. The autoimmune process eventually leads to a loss of hypocretin neurons in the lateral hypothalamus. Epidemiological studies in several countries proved an increased incidence of narcolepsy after H1N1 flu vaccination and infection. This survey in 30 sleep centers in Switzerland led to the identification of 9 H1N1-vaccinated children and adults as newly diagnosed narcolepsy. Clinical features included the abrupt and severe onset of sleepiness, cataplexy and sleep fragmentation.

Sleep-wake disorders persist 18 months after traumatic brain injury but remain underrecognized

OBJECTIVE This study is a prospective, controlled clinical and electrophysiologic trial examining the chronic course of posttraumatic sleep-wake disturbances (SWD). METHODS We screened 140 patients with acute, first-ever traumatic brain injury of any severity and included 60 patients for prospective follow-up examinations. Patients with prior brain trauma, other neurologic or systemic disease, drug abuse, or psychiatric comorbidities were excluded. Eighteen months after trauma, we performed detailed sleep assessment in 31 participants. As a control group, we enrolled healthy individuals without prior brain trauma matched for age, sex, and sleep satiation. RESULTS In the chronic state after traumatic brain injury, sleep need per 24 hours was persistently increased in trauma patients (8.1 ± 0.5 hours) as compared to healthy controls (7.1 ± 0.7 hours). The prevalence of chronic objective excessive daytime sleepiness was 67% in patients with brain trauma compared to 19% in controls. Patients significantly underestimated excessive daytime sleepiness and sleep need, emphasizing the unreliability of self-assessments on SWD in trauma patients. CONCLUSIONS This study provides prospective, controlled, and objective evidence for chronic persistence of posttraumatic SWD, which remain underestimated by patients. These results have clinical and medicolegal implications given that SWD can exacerbate other outcomes of traumatic brain injury, impair quality of life, and are associated with public safety hazards.

Definition and diagnostic criteria of sleep-related hypermotor epilepsy

The syndrome known as nocturnal frontal lobe epilepsy is recognized worldwide and has been studied in a wide range of clinical and scientific settings (epilepsy, sleep medicine, neurosurgery, pediatric neurology, epidemiology, genetics). Though uncommon, it is of considerable interest to practicing neurologists because of complexity in differential diagnosis from more common, benign sleep disorders such as parasomnias, or other disorders like psychogenic nonepileptic seizures. Moreover, misdiagnosis can have substantial adverse consequences on patients' lives. At present, there is no consensus definition of this disorder and disagreement persists about its core electroclinical features and the spectrum of etiologies involved. To improve the definition of the disorder and establish diagnostic criteria with levels of certainty, a consensus conference using formal recommended methodology was held in Bologna in September 2014. It was recommended that the name be changed to sleep-related hypermotor epilepsy (SHE), reflecting evidence that the attacks are associated with sleep rather than time of day, the seizures may arise from extrafrontal sites, and the motor aspects of the seizures are characteristic. The etiology may be genetic or due to structural pathology, but in most cases remains unknown. Diagnostic criteria were developed with 3 levels of certainty: witnessed (possible) SHE, video-documented (clinical) SHE, and video-EEG-documented (confirmed) SHE. The main research gaps involve epidemiology, pathophysiology, treatment, and prognosis.

Sleep-disordered breathing among acute ischemic stroke patients in Brazil.

OBJECTIVES Sleep-disordered breathing (SDB) is very common in acute stroke patients and has been related to poor outcome. However, there is a lack of data about the association between SDB and stroke in developing countries. The study aims to characterize the frequency and severity of SDB in Brazilian patients during the acute phase of ischemic stroke; to identify clinical and laboratorial data related to SDB in those patients; and to assess the relationship between sleep apnea and functional outcome after six months of stroke. METHODS Clinical data and laboratorial tests were collected at hospital admission. The polysomnography was performed on the first night after stroke symptoms onset. Functional outcome was assessed by the modified Rankin Scale (mRS). RESULTS We prospectively evaluated 69 patients with their first-ever acute ischemic stroke. The mean apnea-hypopnea index (AHI) was 37.7 ± 30.2. Fifty-three patients (76.8%) exhibited an AHI ≥ 10 with predominantly obstructive respiratory events (90.6%), and thirty-three (47.8%) had severe sleep apnea. Age (OR: 1.09; 95% CI: 1.03-1.15; p= 0.004) and hematocrit (OR: 1.18; 95% CI: 1.03-1.34; p= 0.01) were independent predictors of sleep apnea. Age (OR: 1.13; 95% CI: 1.03-1.24; p= 0.01), body mass index (OR: 1.54; 95% CI: 1.54-2.18; p= 0.01), and hematocrit (OR: 1.19; 95% CI: 1.01-1.40; p= 0.04) were independent predictors of severe sleep apnea. The National Institutes of Health Stroke Scale (NIHSS; OR: 1.30; 95% CI: 1.1-1.5; p= 0.001) and severe sleep apnea (OR: 9.7; 95% CI: 1.3-73.8; p= 0.03) were independently associated to mRS >2 at six months, after adjusting for confounders. CONCLUSION Patients with acute ischemic stroke in Brazil have a high frequency of SDB. Severe sleep apnea is associated with a poor long-term functional outcome following stroke in that population.