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Sleep loss disrupts the neural signature of successful learning.
Guttesen, AÁV, Gaskell, MG, Madden, EV, Appleby, G, Cross, ZR, Cairney, SA
Cerebral cortex (New York, N.Y. : 1991). 2023;33(5):1610-1625
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Understanding how sleep disturbances impair learning and memory is increasingly important in modern society, where many people fail to regularly obtain an adequate amount of sleep. The aim of this study was to investigate the relationship between sleep-associated consolidation and next-day learning and how suppressing slow-wave activity (SWA) [during slow-wave sleep, electrical activity in the brain changes while the body relaxes into deep and restorative rest] contributes to this relationship. This study was a within-subjects (n = 30), crossover design which showed that sleep improved both memory retention and next-day learning however, there was no evidence of a relationship between these measures or with SWA. Furthermore, an absence of sleep disrupts the neural operations underpinning memory encoding, leading to suboptimal performance. Authors conclude that an extended lack of sleep might disrupt the ability to draw upon semantic knowledge when encoding novel associations, necessitating the use of more surface-based and ultimately suboptimal routes to learning.
Abstract
Sleep supports memory consolidation as well as next-day learning. The influential "Active Systems" account of offline consolidation suggests that sleep-associated memory processing paves the way for new learning, but empirical evidence in support of this idea is scarce. Using a within-subjects (n = 30), crossover design, we assessed behavioral and electrophysiological indices of episodic encoding after a night of sleep or total sleep deprivation in healthy adults (aged 18-25 years) and investigated whether behavioral performance was predicted by the overnight consolidation of episodic associations from the previous day. Sleep supported memory consolidation and next-day learning as compared to sleep deprivation. However, the magnitude of this sleep-associated consolidation benefit did not significantly predict the ability to form novel memories after sleep. Interestingly, sleep deprivation prompted a qualitative change in the neural signature of encoding: Whereas 12-20 Hz beta desynchronization-an established marker of successful encoding-was observed after sleep, sleep deprivation disrupted beta desynchrony during successful learning. Taken together, these findings suggest that effective learning depends on sleep but not necessarily on sleep-associated consolidation.
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Paroxysmal slow wave events are associated with cognitive impairment in patients with obstructive sleep apnea.
Li, M, Sun, Z, Sun, H, Zhao, G, Leng, B, Shen, T, Xue, S, Hou, H, Li, Z, Zhang, J
Alzheimer's research & therapy. 2022;14(1):200
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Obstructive sleep apnoea (OSA) is a disorder which results in an individual’s breathing being cut off momentarily whilst asleep. OSA has been associated with the development of cognitive impairment, which is characterised by declining memory. The reason for the link is thought to involve a dysfunction in the blood brain barrier, which can be measured by paroxysmal slow wave events (PSWEs). This study of 339 individuals with complaints of snoring aimed to determine the correlation between PSWEs and cognitive impairment. The results showed that cognitive impairment in individuals with OSA due to a lack of oxygen could be due to a dysfunction in the blood brain barrier and that PSWEs are a reliable measure of this. It was concluded that PSWEs can be used as a measure of cognitive impairment in patients with OSA and that brain barrier dysfunction may be involved in its development in this subset of individuals. This study could be used by healthcare professionals to understand that sleep apnoea is more than just snoring, it can be involved in the development of certain chronic diseases.
Abstract
BACKGROUND Increasing evidence has supported a link between obstructive sleep apnea (OSA) and cognition, and blood-brain barrier (BBB) dysfunction which can be reflected by paroxysmal slow wave events (PSWEs) may be a potential mechanism. The purpose of our study was to investigate the correlation between the PSWEs and cognitive impairment in patients with OSA, with a focus on the possible mechanism. METHODS In total, 339 subjects with subjective snoring complaints from the Sleep Medicine Center underwent magnetic resonance imaging and whole-night polysomnography. OSA was defined as apnea-hypopnea index (AHI) ≥ 5 events/h. MCI was defined as the MoCA < 26 and met the criteria: (1) subjective cognitive impairment; (2) objective impairment in one or more cognitive domains; (3) slightly impaired complex instrumental daily abilities, but independent daily living abilities; and (4) no dementia. The PSWEs calculated by self-developed Python scripts were defined for EEG recordings as a median power frequency of < 6 Hz for more than five consecutive seconds. Serum cyclophilin A (CyPA) and matrix metalloproteinase-9 (MMP-9) levels and amyloid-β 42 levels in neuron-derived exosomes were determined. The participants who received continuous positive airway pressure (CPAP) were followed up and their PSWEs were recalculated after 1 year of treatment. RESULTS A total of 339 participants were divided into the OSA+MCI group (n = 157), OSA-MCI group (n = 118), and controls (normal cognitive state without OSA) (n = 64). The total PSWEs and the occurrence per minute of PSWEs at stage REM in the OSA+MCI group were higher than those in the OSA-MCI and control groups. The duration ratio of PSWEs at stage REM in the OSA+MCI group significantly increased. The total PSWEs and PSWEs at the F4-M1, O1-M2, and O2-M1 channels in stage REM were independently associated with cognitive impairment in OSA patients. There were positive correlations between the PSWEs and serum CyPA and MMP-9 levels in patients with OSA. The mediation analysis showed that the relationship between mean SaO2 and percentage of sleep time spent with oxygen saturation <90% with MoCA scores was mediated by the total PSWEs (proportion of mediation 77.89% and 82.89%). The PSWEs were negatively correlated with global cognitive performance and cognitive subdomains. After 1 year of CPAP treatment, the total PSWEs, PSWEs in stage REM, and serum CyPA and MMP-9 levels decreased significantly, and MoCA scores were improved compared with baseline. CONCLUSIONS The PSWEs were implicated in cognitive impairment in patients with OSA, and the mechanisms of cognitive impairment due to hypoxia in OSA patients could be BBB dysfunction. The PSWEs can be used as a marker of cognitive impairment in patients with OSA. TRIAL REGISTRATION This trial is registered on the Chinese Clinical Trial Registry, number ChiCTR1900021544. The trial was registered on February 27, 2019.
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Limbic-thalamo-cortical projections and reward-related circuitry integrity affects eating behavior: A longitudinal DTI study in adolescents with restrictive eating disorders.
Olivo, G, Wiemerslage, L, Swenne, I, Zhukowsky, C, Salonen-Ros, H, Larsson, EM, Gaudio, S, Brooks, SJ, Schiöth, HB
PloS one. 2017;12(3):e0172129
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This is a highly specialised and technical observational study using brain imaging techniques to investigate longitudinal changes in the brain white matter micro-structure in adolescent patients with restrictive eating disorders (e.g. anorexia nervosa). Twelve patients and twenty-four controls were enrolled into this study. Patients were scanned at diagnosis and after one year of family-based treatment. Brain imaging results were correlated with weight/BMI as well as clinical features of the eating disorder. The observed changes in specific regions of the brain support the hypothesis that neural pathway related to taste processing and reward-related regions are involved, and determine an alteration in food-related cognitive processing in adolescents, leading to restrictive eating behaviour. The observed changes in brain micro-structure appeared to revert after one year of follow-up. This suggests that a prompt intervention might be effective in arresting the disruption of white matter integrity that occurs during the first phases of the eating disorder, and that early treatment is of particular importance in adolescents, as during adolescence processes relating to neuronal structuring and neuroplasticity are at their maximum.
Abstract
Few studies have used diffusion tensor imaging (DTI) to investigate the micro-structural alterations of WM in patients with restrictive eating disorders (rED), and longitudinal data are lacking. Twelve patients with rED were scanned at diagnosis and after one year of family-based treatment, and compared to twenty-four healthy controls (HCs) through DTI analysis. A tract-based spatial statistics procedure was used to investigate diffusivity parameters: fractional anisotropy (FA) and mean, radial and axial diffusivities (MD, RD and AD, respectively). Reduced FA and increased RD were found in patients at baseline in the corpus callosum, corona radiata and posterior thalamic radiation compared with controls. However, no differences were found between follow-up patients and controls, suggesting a partial normalization of the diffusivity parameters. In patients, trends for a negative correlation were found between the baseline FA of the right anterior corona radiata and the Eating Disorder Examination Questionnaire total score, while a positive trend was found between the baseline FA in the splenium of corpus callosum and the weight loss occurred between maximal documented weight and time of admission. A positive trend for correlation was also found between baseline FA in the right anterior corona radiata and the decrease in the Obsessive-Compulsive Inventory Revised total score over time. Our results suggest that the integrity of the limbic-thalamo-cortical projections and the reward-related circuitry are important for cognitive control processes and reward responsiveness in regulating eating behavior.
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Moderate Physical Activity Mediates the Association between White Matter Lesion Volume and Memory Recall in Breast Cancer Survivors.
Cooke, GE, Wetter, NC, Banducci, SE, Mackenzie, MJ, Zuniga, KE, Awick, EA, Roberts, SA, Sutton, BP, McAuley, E, Kramer, AF
PloS one. 2016;11(2):e0149552
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As survival rates of breast cancer increase, the long-term cognitive effects of disease and required treatment are emerging. The underlying pathways of cancer-related cognitive impairment involve accelerated aging of the brain, low levels of physical activity and decreased cognitive function, however these links have not been adequately explored. The aim of this study was to investigate the link between physical activity, white matter lesion volume and cognition in 30 breast cancer survivors and 28 age-matched controls. The results of this study showed that brain structure significantly predicted cognitive function. This study provided evidence suggesting that moderate physical activity may help reduce the treatment related risks associated with breast cancer.
Abstract
Increased survival rates among breast cancer patients have drawn significant attention to consequences of both the presence of cancer, and the subsequent treatment-related impact on the brain. The incidence of breast cancer and the effects of treatment often result in alterations in the microstructure of white matter and impaired cognitive functioning. However, physical activity is proving to be a successful modifiable lifestyle factor in many studies that could prove beneficial to breast cancer survivors. This study investigates the link between white matter lesion volume, moderate physical activity, and cognition in breast cancer survivors following treatment compared to non-cancer age-matched controls. Results revealed that brain structure significantly predicted cognitive function via mediation of physical activity in breast cancer survivors. Overall, the study provided preliminary evidence suggesting moderate physical activity may help reduce the treatment related risks associated with breast cancer, including changes to WM integrity and cognitive impairment.
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Reversal of cognitive decline: a novel therapeutic program.
Bredesen, DE
Aging. 2014;6(9):707-17
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Alzheimer’s Disease (AD) is estimated to affect 30 million individuals globally, with projections as high as 150 million by 2050 if no effective treatment is found. This report describes a personalised, multi-modal, therapeutic programme used with 10 individuals with various degrees of cognitive decline. The goal was to optimise metabolic parameters and lifestyle factors and was personalised based on laboratory test results. 9 out of 10 of the case study patients experienced improvement in cognitive abilities, beginning within 3-6 months of starting the programme. These effects were sustained at 2.5 year follow up. The 1 patient who did not benefit had advanced AD, in comparison to the other patients with subjective or mild cognitive decline. The authors call for a more extensive trial of the therapeutic programme.
Abstract
This report describes a novel, comprehensive, and personalized therapeutic program that is based on the underlying pathogenesis of Alzheimer's disease, and which involves multiple modalities designed to achieve metabolic enhancement for neurodegeneration (MEND). The first 10 patients who have utilized this program include patients with memory loss associated with Alzheimer's disease (AD), amnestic mild cognitive impairment (aMCI), or subjective cognitive impairment (SCI). Nine of the 10 displayed subjective or objective improvement in cognition beginning within 3-6 months, with the one failure being a patient with very late stage AD. Six of the patients had had to discontinue working or were struggling with their jobs at the time of presentation, and all were able to return to work or continue working with improved performance. Improvements have been sustained, and at this time the longest patient follow-up is two and one-half years from initial treatment, with sustained and marked improvement. These results suggest that a larger, more extensive trial of this therapeutic program is warranted. The results also suggest that, at least early in the course, cognitive decline may be driven in large part by metabolic processes. Furthermore, given the failure of monotherapeutics in AD to date, the results raise the possibility that such a therapeutic system may be useful as a platform on which drugs that would fail as monotherapeutics may succeed as key components of a therapeutic system.
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Effectiveness and safety of citicoline in mild vascular cognitive impairment: the IDEALE study.
Cotroneo, AM, Castagna, A, Putignano, S, Lacava, R, Fantò, F, Monteleone, F, Rocca, F, Malara, A, Gareri, P
Clinical interventions in aging. 2013;8:131-7
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The number of people aged 65 years and over with mild vascular cognitive impairment is continuing to increase. Vascular disease can reduce cerebral perfusion, causing oxidative stress and neurodegeneration. Citicoline [pharmaceutical] inhibits apoptosis associated with cerebral ischemia and in several models of neurodegeneration has been able to potentiate neuroplasticity. The aim of this study was to assess the effectiveness and safety of oral citicoline in elderly people with mild vascular cognitive impairment. A total of 349 patients were included in the study who were assigned to open-label treatment with oral citicoline 500 mg twice a day in a fasting state or to no treatment (controls). Results show that citicoline is effective and safe in the treatment of mild vascular cognitive impairment. The treated group showed improvement in MMSE (Mini-Mental State Examination) scores, with an increase of 0.5 points shown over the course of the study. Authors conclude that further studies are required in order to confirm the findings of this study, and to further assess the efficacy and safety of long-term administration of a dietary supplement such as Cytidine-5′-diphosphate choline.
Abstract
BACKGROUND The studio di intervento nel decadimento vascolare lieve (IDEALE study) was an open multicenter Italian study, the aim of which was to assess the effectiveness and safety of oral citicoline in elderly people with mild vascular cognitive impairment. METHODS The study was performed in 349 patients. The active or citicoline group was composed of 265 patients and included 122 men and 143 women of mean age 79.9 ± 7.8 years selected from six Italian regions. Inclusion criteria were age ≥ 65 years, Mini-Mental State Examination (MMSE) score ≥ 21, subjective memory complaints but no evidence of deficits on MMSE, and evidence of vascular lesions on neuroradiology. Those with probable Alzheimer's disease were excluded. The control group consisted of 84 patients, including 36 men and 48 women of mean age 78.9 ± 7.01 (range 67-90) years. Patients included in the study underwent brain computed tomography or magnetic resonance imaging, and plasma dosage of vitamin B12, folate, and thyroid hormones. Functional dependence was investigated by scores on the Activities of Daily Living (ADL) and Instrumental Activities of Daily Living (IADL) scales, mood was assessed by the Geriatric Depression Scale (GDS), and behavioral disorders using the Neuropsychiatric Inventory scale. Comorbidity was assessed using the Cumulative Illness Rating Scale. An assessment was made at baseline (T0), after 3 months (T1), and after 9 months (T2, ie, 6 months after T1). The main outcomes were an improvement in MMSE, ADL, and IADL scores in the study group compared with the control group. Side effects were also investigated. The study group was administered oral citicoline 500 mg twice a day throughout the study. RESULTS MMSE scores remained unchanged over time (22.4 ± 4 at T0; 22.7 ± 4 at T1; 22.9 ± 4 at T2), whereas a significant difference was found between the study and control groups, both in T1 and in T2. No differences were found in ADL and IADL scores between the two groups. A slight but not statistically significant difference was found in GDS score between the study and control groups (P = 0.06). No adverse events were recorded. CONCLUSION In this study, citicoline was effective and well tolerated in patients with mild vascular cognitive impairment. Citicoline activates biosynthesis of phospholipids in neuronal membranes, increases brain metabolism as well as norepinephrine and dopamine levels in the central nervous system, and has neuroprotective effects during hypoxia and ischemia. Therefore, citicoline may be recommended for patients with mild vascular cognitive impairment.