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1.
The neurophysiology of hyperarousal in restless legs syndrome: Hints for a role of glutamate/GABA.
Lanza, G, Ferri, R
Advances in pharmacology (San Diego, Calif.). 2019;:101-119
Abstract
Restless legs syndrome (RLS) is a common sensory-motor circadian disorder, whose basic components include urge to move the legs, unpleasant sensory experience, and periodic leg movements during sleep, all associated with an enhancement of the individual's arousal state. Brain iron deficiency (BID) is considered to be a key initial pathobiological factor, based on alterations of iron acquisition by the brain, also moderated by genetic factors. In addition to the well-known dopaminergic involvement in RLS, previous studies pointed out that BID brings also a hyperglutamatergic state that influences a dysfunctional cortico-striatal-thalamic-cortical circuit in genetically vulnerable individuals. However, the enhancement of arousal mechanisms in RLS may also be explained by functional changes of the ascending arousal systems and by deficitary GABA-mediated inhibitory control. Very recently, it was also suggested that BID induces a hypoadenosinergic state in RLS, thus possibly providing a link for a putative unified pathophysiological mechanism accounting for both hyperarousal and sensory-motor signs. Consequently, RLS might be viewed as a multitransmitter neurochemical disorder, globally resulting in enhanced excitability and decreased inhibition. In this framework, understanding the complex interaction of different neuronal circuits in generating the symptoms of RLS is mandatory both for a better diagnostic refinement and for an innovative therapeutic support. Notably, multiple neurotransmission dysfunction, either primary or triggered by BID, may also bridge the gap between RLS and other chronic pain disorders. This chapter summarizes the current experimental and clinical findings into a heuristic model of the electrophysiology and neurochemistry underlying RLS.
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2.
Catechol-O-methyltransferase, dopamine, and sleep-wake regulation.
Dauvilliers, Y, Tafti, M, Landolt, HP
Sleep medicine reviews. 2015;:47-53
Abstract
Sleep and sleep disorders are complex and highly variable phenotypes regulated by many genes and environment. The catechol-O-methyltransferase (COMT) gene is an interesting candidate, being one of the major mammalian enzymes involved in the catabolism of catecholamines. The activity of COMT enzyme is genetically polymorphic due to a guanine-to-adenine transition at codon 158, resulting in a valine (Val) to methionine (Met) substitution. Individuals homozygous for the Val allele show higher COMT activity, and lower dopaminergic signaling in prefrontal cortex (PFC) than subjects homozygous for the Met allele. Since COMT has a crucial role in metabolising dopamine, it was suggested that the common functional polymorphism in the COMT gene impacts on cognitive function related to PFC, sleep-wake regulation, and potentially on sleep pathologies. The COMT Val158Met polymorphism may predict inter-individual differences in brain electroencephalography (EEG) alpha oscillations and recovery processes resulting from partial sleep loss in healthy individuals. The Val158Met polymorphism also exerts a sexual dimorphism and has a strong effect on objective daytime sleepiness in patients with narcolepsy-cataplexy. Since the COMT enzyme inactivates catecholamines, it was hypothesized that the response to stimulant drugs differs between COMT genotypes. Modafinil maintained executive functioning performance and vigilant attention throughout sleep deprivation in subjects with Val/Val genotype, but less in those with Met/Met genotype. Also, homozygous Met/Met patients with narcolepsy responded to lower doses of modafinil compared to Val/Val carriers. We review here the critical role of the common functional COMT gene polymorphism, COMT enzyme activity, and the prefrontal dopamine levels in the regulation of sleep and wakefulness in normal subjects, in narcolepsy and other sleep-related disorders, and its impact on the response to psychostimulants.
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3.
Neural integration of reward, arousal, and feeding: recruitment of VTA, lateral hypothalamus, and ventral striatal neurons.
Gutierrez, R, Lobo, MK, Zhang, F, de Lecea, L
IUBMB life. 2011;(10):824-30
Abstract
The ability to control neuronal activity using light pulses and optogenetic tools has revealed new properties of neural circuits and established causal relationships between activation of a single genetically defined population of neurons and complex behaviors. Here, we briefly review the causal effect of activity of six genetically defined neural circuits on behavior, including the dopaminergic neurons DA in the ventral tegmental area (VTA); the two main populations of medium-sized spiny neurons (D1- and D2-positive) in the striatum; the giant Cholinergic interneurons in the ventral striatum; and the hypocretin- and MCH- expressing neurons in the lateral hypothalamus. We argue that selective spatiotemporal recruitment and coordinated spiking activity among these cell type-specific neural circuits may underlie the neural integration of reward, learning, arousal and feeding.
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4.
The hyperarousal model of insomnia: a review of the concept and its evidence.
Riemann, D, Spiegelhalder, K, Feige, B, Voderholzer, U, Berger, M, Perlis, M, Nissen, C
Sleep medicine reviews. 2010;(1):19-31
Abstract
Primary insomnia is defined as difficulties in falling asleep, maintaining sleep or non-restorative sleep accompanied by significantly impaired daytime functioning in the absence of a specific physical, mental or substance-related cause. The current review provides substantial support for the concept that hyperarousal processes from the molecular to the higher system level play a key role in the pathophysiology of primary insomnia. Autonomous, neuroendocrine, neuroimmunological, electrophysiological and neuroimaging studies demonstrate increased levels of arousal in primary insomnia during both night and daytime. In the light of neurobiological theories of sleep-wake regulation, primary insomnia may be conceptualized as a final common pathway resulting from the interplay between a genetic vulnerability for an imbalance between arousing and sleep-inducing brain activity, psychosocial/medical stressors and perpetuating mechanisms including dysfunctional sleep-related behavior, learned sleep preventing associations and other cognitive factors like tendency to worry/ruminate.
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5.
"Hyperarousal and insomnia: state of the science".
Riemann, D
Sleep medicine reviews. 2010;(1):17
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6.
Children's recall of emotionally arousing, repeated events: a review and call for further investigation.
Price, HL, Connolly, DA
International journal of law and psychiatry. 2008;(4):337-46
Abstract
The influence, if any, of emotional arousal on memory is a controversial topic in the literature. Much of the research on memory for emotionally arousing events has focused on a few specific issues (e.g., differences in types of details recalled in emotionally arousing and neutral events; increasing ecological validity). Although gaining more recent attention, a neglected area in the literature has been memory for instances of repeated, emotionally arousing events. This issue has important implications for understanding children's ability to recall events in a forensic setting. We review existing findings on memory for emotionally arousing events in general and particularly in children, children's memory for events that occur repeatedly, and then discuss the scarce research on repeated emotionally arousing events and the need for further research in this area. We conclude that although it is clear that children are capable of accurately reporting arousing and repeated experiences, it is also apparent that circumstances both within and outside the control of investigative interviewers influence this ability.
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7.
New perspectives for the treatment of disorders of sleep and arousal.
Sanger, DJ, Soubrane, C, Scatton, B
Annales pharmaceutiques francaises. 2007;(4):268-74
Abstract
A variety of molecules with novel mechanisms of action are currently being evaluated for their potential as treatments for sleep disorders. The GABA-A receptor complex remains an important target for hypnotic drugs (eg gaboxadol, indiplon). However, drugs acting through histamine, calcium channels and serotonin receptors may also be of interest for the treatment of insomnia. In the case of the 5HT2A subtype of serotonin receptors, several molecules which improve sleep maintenance and modify sleep architecture by increasing slow wave sleep are currently being tested (eg eplivanserin). Two new drugs with efficacy in excessive sleepiness (modafinil, sodium oxybate) have improved the treatment of this condition. However, the mechanisms of action of these agents are poorly understood. The recent discovery of the hypocretin arousal system in the hypothalamus may aid the identification of additional new drugs. An agonist at receptors for the pineal hormone melatonin is available in some countries (ramelteon) but is currently used only for the treatment of insomnia associated with difficulties of sleep onset. Additional melatonin receptor agonists are being developed and may have potential for treating several conditions including circadian rhythm disorders and depression.
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8.
Effects of modafinil on cognitive performance and alertness during sleep deprivation.
Wesensten, NJ
Current pharmaceutical design. 2006;(20):2457-71
Abstract
The performance- and alertness-sustaining/restoring effects of modafinil during sleep deprivation in normal, healthy adults were reviewed. Results indicate that modafinil is efficacious for sustaining/restoring objective performance and alertness during sleep deprivation with few adverse effects. At appropriate dosages, modafinil restores performance and alertness to non-sleep deprived levels. Modafinil also impairs post-sleep deprivation recovery sleep, but from the few studies available addressing this issue, it is unclear whether these sleep impairments translate into post-sleep performance impairments. Further research is needed to determine whether modafinil restores performance on simple cognitive tasks only or whether modafinil additionally restores executive functions (e.g., abstract thought, critical reasoning, planning, decision-making, situational awareness, and effective judgment) which are critical in most modern operational settings. In addition, studies are needed to determine whether modafinil use during sleep deprivation is preferable to that of other available controlled stimulants (such as dextroamphetamine) or non-controlled stimulants (such as caffeine). Such studies would be comprised of direct, head-to-head comparisons among various stimulants across a range of dosages.
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9.
Sudden infant deaths: stress, arousal and SIDS.
Kahn, A, Groswasser, J, Franco, P, Scaillet, S, Sawaguchi, T, Kelmanson, I, Dan, B
Early human development. 2003;:S147-66
Abstract
The prevalence of the Sudden Infant Death Syndrome (SIDS) has dropped in most countries following the development of education campaigns on the avoidance of preventable risk factors for SIDS. These include factors in the infant's micro environment, such as prenatal passive smoking, administration of sedative drugs, prone sleep, high ambient temperature or sleeping with the face covered. Sleep laboratory studies have shown that these risk conditions contribute to the development of respiratory and autonomic disorders and reduce the child's arousability. The opposite effects were seen when studying factors protective from SIDS, such as breastfeeding or the use of a pacifier. In victims of SIDS, similar breathing, autonomic and arousal characteristics were recorded days or weeks before their death. It is concluded that in some infants, already immature control mechanisms can be aggravated by environmental factors.
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10.
The effects of stressful life events, coping, and cortisol on HIV infection.
Leserman, J
CNS spectrums. 2003;(1):25-30
Abstract
What is the role of stress and coping in changes in immunologic and clinical indicators of human immunodeficiency virus disease progression? There is substantial evidence that stressful life events and passive coping strategies, such as denial, may have a detrimental effect on HIV disease progression. Given the harmful effects of stress and passive coping, the author reviews the limited research testing the efficacy of interventions, such as cognitive-behavioral therapies for HIV-infected persons. Finally, in trying to understand psychoimmune relationships in HIV, the evidence is examined for the mediating and direct effects of cortisol, a hormone associated with stress, on HIV disease progression. Delineating the role of psychosocial factors and cortisol on HIV disease progression may aid in the development of new interventions for this devastating disease.