The Sleep Side of Aging and Alzheimer's Disease.

As we age, sleep patterns undergo significant modifications in micro and macrostructure, worsening cognition and quality of life. These are associated with remarkable brain changes, like deterioration in synaptic plasticity, gray and white matter, and significant modifications in hormone levels. Sleep alterations are also a core component of mild cognitive impairment (MCI) and Alzheimer's Disease (AD). AD night time is characterized by a gradual decrease in slow-wave activity and a substantial reduction of REM sleep. Sleep abnormalities can accelerate AD pathophysiology, promoting the accumulation of amyloid-ß (Aß) and phosphorylated tau. Thus, interventions that target sleep disturbances in elderly people and MCI patients have been suggested as a possible strategy to prevent or decelerate conversion to dementia. Although cognitive-behavioral therapy and pharmacological medications are still first-line treatments, despite being scarcely effective, new interventions have been proposed, such as sensory stimulation and Noninvasive Brain Stimulation (NiBS). The present review outlines the current state of the art of the relationship between sleep modifications in healthy aging and the neurobiological mechanisms underlying age-related changes. Furthermore, we provide a critical analysis showing how sleep abnormalities influence the prognosis of AD pathology by intensifying Aß and tau protein accumulation. We discuss potential therapeutic strategies to target sleep disruptions and conclude that there is an urgent need for testing new therapeutic sleep interventions.

Treatment-emergent central sleep apnoea after surgery for obstructive sleep apnoea.

Central sleep apnoea (CSA) is a lack of drive to breathe during sleep, which can occur in physiologic as well as in pathologic conditions. A particular type of CSA, defined treatment-emergent CSA (TECSA), may occur after the treatment of obstructive sleep apnoea syndrome (OSAS), either with CPAP or surgery. TECSA is transitory and seems to be related to the severity of OSAS. We describe a 51-year-old man affected by severe OSAS who developed severe, transient CSA immediately after upper airways surgery. We believe that CSA was triggered by the sudden variation in nocturnal arterial PCO2, which decreased from 52.3 mmHg before surgery to 42.0 mmHg after surgery. It is conceivable that, due to long-lasting severe OSAS, our patient lowered his chemosensitivity to PCO2. Consequently, the resolution of obstructive apnoeas and the restoration of normal nocturnal values of PCO2 may have reduced the nocturnal PCO2 to the point of being inadequate to stimulate ventilation.

Evaluation of pharyngeal muscle activity through nasopharyngeal surface electromyography in a cohort of dysphagic patients with acute ischaemic stroke.

Oro-pharyngeal dysphagia is frequently present during the acute phase of stroke. The aim of the present study was to evaluate whether the recording of surface EMG using a nasopharyngeal (NP) electrode could be applied to evaluation of pharyngeal muscle activity in acute stroke patients and if this neurophysiological measure is related with clinical assessment of swallowing. Patients were examined and clinical severity was assessed with the National Institute of Health Stroke Scale (NIHSS) score; dysphagia was evaluated through bedside screening test using the Gugging Swallowing Scale (GUSS). Extension of the ischaemic lesion was measured by quantitative score, based on CT scan [Alberta Stroke Programme Early CT Score (ASPECTS)]. We analysed 70 patients; 50 were classified as dysphagic (Dys+), and 20 as non-dysphagic (Dys-). Each participant underwent a surface NP EMG recording performed with a NP electrode, made of a Teflon isolated steel catheter, with a length of 16 cm and a tip diameter of 1.5 mm. The electrode was inserted through the nasal cavity, rotated and positioned approximately 3 mm anteroinferior to the salpingo-palatine fold. At least four consecutive swallowing-induced EMG bursts were recorded and analysed for each participant. Swallowing always induced a repetitive, polyphasic burst of activation of the EMG, lasting around 0.25 to 1 sec, with an amplitude of around 100-600mV. Two parameters of the EMG potentials recorded with the NP electrode were analyzed: duration and amplitude. The duration of the EMG burst was increased in Dys+ patients with a statistically significant difference compared to Dys- patients (p < 0.001). The amplitude was slightly reduced in the Dys+ group, but statistically significant differences were not observed (p = 0,775). Nevertheless, the burst amplitude showed a significant inverse correlation with NIHSS [r(48) = -0.31; p < 0.05] and ASPECTS scores [r(48) = -0.27; p < 0.05], meaning that the burst amplitude progressively reduced with an increase of clinical severity (NIHSS) and topographic extension of brain lesions in CT (ASPECTS). These results suggest that NP recordings can give a semi-quantitative measure of swallowing difficulties originating from pharyngeal dysfunction, in fact, electromyographic findings suggest reduced pharyngeal motility.

Abdominal acupuncture reduces laser-evoked potentials in healthy subjects.

OBJECTIVE: Acupuncture is known to reduce clinical pain, although the exact mechanism is unknown. The aim of the current study was to investigate the effect of acupuncture on laser-evoked potential amplitudes and laser pain perception. METHODS: In order to evaluate whether abdominal acupuncture is able to modify pain perception, 10 healthy subjects underwent a protocol in which laser-evoked potentials (LEPs) and laser pain perception were collected before the test (baseline), during abdominal acupuncture, and 15 min after needle removal. The same subjects also underwent a similar protocol in which, however, sham acupuncture without any needle penetration was used. RESULTS: During real acupuncture, both N1 and N2/P2 amplitudes were reduced, as compared to baseline (p<0.01). The reduction lasted up to 15 min after needle removal. Furthermore, laser pain perception was reduced during real acupuncture, although the difference was marginally significant (p=0.06). CONCLUSIONS: Our results show that abdominal acupuncture reduces LEP amplitude in healthy subjects. SIGNIFICANCE: Our results provide a theoretical background for the use of abdominal acupuncture as a therapeutic approach in the treatment of pain conditions. Future studies will have to be conducted in clinical painful syndromes, in order to confirm the analgesic effect of acupuncture in patients suffering from pain.

Hyoid myotomy without suspension: a surgical approach to obstructive sleep apnoea syndrome.

The aim of this study was to verify if hyoid myotomy without hyoid suspension is effective in surgical treatment of obstructive sleep apnoea syndrome (OSAS). We recruited six patients with OSAS, aged between 34 to 60 years, with retropalatal and retrolingual upper airway obstruction, non-obese (BMI < 27) and non-compliant to continuous positive airway pressure therapy. Pre-surgical clinical and instrumental evaluations included clinical examination, cephalometry, polysomnography (PSG) and sleep endoscopy. Surgical treatment included nasal surgery, uvulopalatopharyngoplasty, tonsillectomy and hyoid myotomy without hyoid suspension. Follow-up evaluations were performed with serial PSGs, performed early (one week after surgery), and at 1, 6 and 18 months after surgery. We observed that surgery was followed by immediate normalisation of breathing parameters evaluated by PSG that persisted after 18 months. Thus, hyoid myotomy without suspension combined with nasal and palatal surgery may be considered a valid treatment of non-obese OSAS patients with retrolingual and retropalatal collapse. Furthermore, we suggest that hyoid bone suspension, binding it to mandibular or to thyroid cartilage, might be unnecessary in selected cases.

Psychological functioning measures in patients with primary insomnia and sleep state misperception.

OBJECTIVE: Sleep state misperception (SSM) is a term used in the International Classification of Sleep Disorders to indicate people who mistakenly perceive their sleep as wakefulness. SSM is a form of primary insomnia. The aim of this study was to record psychological functioning measures (anxiety, depression, ability to feel pleasure, obsessive-compulsive traits) in a population of patients with primary insomnia and to evaluate the relationship between these measures and the patients' perception of their sleep. MATERIALS AND METHODS: Seventy-six consecutive patients with primary insomnia were enrolled: 34 men and 42 women, mean age 53.9 ± 13.1. Sleep study included the following: Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Berlin's Questionnaire and home-based polysomnography. Psychometric evaluation included the following: Self-Administered Anxiety Scale, Beck's Depression Inventory, Maudsley's Obsessive Compulsive Inventory, Snaith-Hamilton Pleasure Scale, Eating Attitude Test. RESULTS: All patients with insomnia had psychometric scores higher than the general population, but very few patients, in both groups, had anxiety or depression scores consistent with severe mood or anxiety disorders. Comparisons between subjective and objective scores confirmed that most sleep parameters were underestimated. Patients with SSM had lower anxiety scores as compared to patients without SSM. CONCLUSIONS: The study did not succeed in identifying any predictor of sleep misperception. We speculate that a group of patients, rather than being extremely worried by their insomnia, may have a sort of agnosia of their sleep.

Evidence of different spinal pathways for the warmth evoked potentials.

OBJECTIVE: To investigate the presence of multiple spinothalamic pathways for warmth in the human spinal cord. METHODS: Laser evoked potentials to C-fiber stimulation (C-LEPs) were recorded in 15 healthy subjects after warmth stimulation of the dorsal midline at C5, T2, T6, and T10 vertebral levels. This method allowed us to calculate the spinal conduction velocity (CV) in two different ways: (1) the reciprocal of the slope of the regression line was obtained from the latencies of the different C-LEP components, and (2) the distance between C5 and T10 was divided by the latency difference of the responses at the two sites. In particular, we considered the C-N1 potential, generated in the second somatosensory (SII) area, and the late C-P2 response, generated in the anterior cingulate cortex (ACC). RESULTS: The calculated CV of the spinal fibers generating the C-N1 potential (around 2.5m/s) was significantly different (p<0.01) from the one of the pathway producing the P2 response (around 1.4m/s). CONCLUSIONS: Our results suggest that the C-N1 and the C-P2 components are generated by two parallel spinal pathways. SIGNIFICANCE: Warmth sensation is subserved by parallel spinothalamic pathways, one probably reaching the SII area, the other the ACC.

The dissociation energy of the new diatomic molecules SiPb and GePb.

The diatomic molecules SiPb and GePb were for the first time identified by producing high temperature vapors of the constituent pure elements in a "double-oven-like" molecular-effusion assembly. The partial pressures of the atomic, heteronuclear, and homonuclear gaseous species observed in the vapor, namely, Si, Ge, Pb, SiPb, GePb, Pb2, Gen, and Sin (n=2-3), were mass-spectrometrically measured in the overall temperature ranges 1753-1961 K (Ge-Pb) and 1992-2314 K (Si-Pb). The dissociation energies of the new species were determined by second- and third-law analyses of both the direct dissociation reactions and isomolecular exchange reactions involving homonuclear molecules. The selected values of the dissociation energies at 0 K (D0 degrees) are 165.1+/-7.3 and 141.6+/-6.9 kJ/mol, respectively, for SiPb and GePb, and the corresponding enthalpies of formation (DeltafH0 degrees) are 476.4+/-7.3 and 419.3+/-6.9 kJ/mol. The ionization efficiency curves of the two species were measured, giving the following values for the first ionization energies: 7.0+/-0.2 eV (SiPb) and 7.1+/-0.2 eV (GePb). A computational study of the species SiPb and GePb was also carried out at the CCSD(T) level of theory using the relativistic electron core potential approach. Molecular parameters, adiabatic ionization energies, adiabatic electron affinities, and dissociation energies of the title species were calculated, as well as the enthalpy changes of the exchange reactions involving the other Pb-containing diatomics of group 14. Finally, a comparison between the experimental and theoretical results is presented, and from a semiempirical correlation the unknown dissociation energies of the SiSn and PbC molecules are predicted as 234+/-7 and 185+/-11 kJ/mol, respectively.