Neurochemical Mechanisms Research Articles

The Role of Vitamin D in Sleep Disorders of Children and Adolescents: A Systematic Review.

This review investigates the association between vitamin D and sleep disorders. Vitamin D is an essential nutrient known to play an important role in the growth and bone health of the human body, but it also appears to play a role in sleep. The goal of our review is to examine the association between vitamin D and sleep disorders in children and adolescents. We summarize the evidence about the role and the mechanism of action of vitamin D in children and adolescents with sleep disorders such as insomnia, obstructive sleep apnea (OSA), restless legs syndrome (RLS), and other sleep disorders. Systematic electronic database searches were conducted using Pubmed and Cochrane Library. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guideline was followed. The studies that met the established inclusion criteria were analyzed and compared. Results suggest a strict relationship between vitamin D deficiency in children and sleep disorders. There is evidence that vitamin D is implicated in the different neurochemical mechanisms involved in sleep regulation and mainly in the serotonergic and dopaminergic pathways. This might be responsible for the association of vitamin D deficiency and restless sleep, sleep hyperhidrosis, OSA, and RLS.

Про можливі нові нейрохімічні механізми патогенезу епілепсії

Відповідно до гіпотези, під час епілепсії в головному мозку відбувається постійне накопичення епілептогенних речовин, що в процесі епілептичної активності мозку зазнають метаболічних змін, необхідних для їх видалення (елімінації) з організму. Коли концентрація епілептогенних речовин у головному мозку досягає порогової величини, вони викликають напад, а в більш низьких концентраціях — епілептичну активність, характерну для міжнападного періоду. У гіпотезі розглядаються такі клінічні прояви епілепсії, як насильницька нормалізація електроенцефалограми, посилення епілептичної активності під час депривації сну як один із парадоксальних ефектів антиепілептичних препаратів при лікуванні епілепсії, яким є феномен, коли призначення антиепілептичних засобів супроводжується покращанням електроенцефалографічної картини, але з погіршенням клініки та почастішанням нападів, а зміна препаратів призводить до оберненого результату — поліпшення клінічної та погіршення електроенцефалографічної картини. Згідно з доповненням до гіпотези, епілептичні речовини, крім того, що під час епілептичної активності мозку зазнають метаболічних перетворень, необхідних для їх подальшого видалення з організму, мають альтернативні нейрохімічні метаболічні шляхи перетворень, необхідні для їх подальшого видалення з організму. У світлі доповнення до гіпотези розглядаються сучасні принципи лікування епілепсії. Насильницька нормалізація електроенцефалограми розглядається як один із проявів агравації епілепсії. Автори пропонують назвати феномен, коли призначення антиепілептичних засобів супроводжується покращанням електроенцефалографічної картини, але з погіршенням клініки і почастішанням нападів, а зміна препаратів призводить до оберненого поліпшення клінічної та погіршення електроенцефалографічної картини, клініко-електроенцефалографічною дисоціацією.

Associations among locus coeruleus catecholamines, tau pathology, and memory in aging.

The locus coeruleus (LC) is the brain's major source of the neuromodulator norepinephrine, and is also profoundly vulnerable to the development of Alzheimer's disease (AD)-related tau pathology. Norepinephrine plays a role in neuroprotective functions that may reduce AD progression, and also underlies optimal memory performance. Successful maintenance of LC neurochemical function represents a candidate mechanism of protection against the propagation of AD-related pathology and may facilitate the preservation of memory performance despite pathology. Using [18F]Fluoro-m-tyrosine ([18F]FMT) PET imaging to measure catecholamine synthesis capacity in LC regions of interest, we examined relationships among LC neurochemical function, AD-related pathology, and memory performance in cognitively normal older adults (n = 49). Participants underwent [11C]Pittsburgh compound B and [18F]Flortaucipir PET to quantify β-amyloid (n = 49) and tau burden (n = 42) respectively. In individuals with substantial β-amyloid, higher LC [18F]FMT net tracer influx (Kivis) was associated with lower temporal tau. Longitudinal tau-PET analyses in a subset of our sample (n = 30) support these findings to reveal reduced temporal tau accumulation in the context of higher LC [18F]FMT Kivis. Higher LC catecholamine synthesis capacity was positively correlated with self-reported cognitive engagement and physical activity across the lifespan, established predictors of successful aging measured with the Lifetime Experiences Questionnaire. LC catecholamine synthesis capacity moderated tau's negative effect on memory, such that higher LC catecholamine synthesis capacity was associated with better-than-expected memory performance given an individual's tau burden. These PET findings provide insight into the neurochemical mechanisms of AD vulnerability and cognitive resilience in the living human brain.

Digoxin at sub-cardiotonic dose modulates the anticonvulsive potential of valproate, levetiracetam and topiramate in experimental primary generalized seizures

The prevalence of epilepsy in the world population together with a high percentage of patients resistant to existing antiepileptic drugs (AEDs) stimulates the constant search for new approaches to the treatment of the disease. Previously a significant anticonvulsant potential of cardiac glycoside digoxin has been verified by enhancing a weak activity of AEDs in low doses under screening models of seizures induced by pentylenetetrazole and maximal electroshock. The aim of the present study is to investigate the influence of digoxin at a sub-cardiotonic dose on the anticonvulsant activity of valproate, levetiracetam, and topiramate in models of primary generalized seizures with different neurochemical mechanisms. A total of 264 random-bred male albino mice have been used. AEDs were administered 30 min before seizure induction once intragastrically at conditionally effective (ED50) and sub-effective (½ ED50) doses: sodium valproate and topiramate – at doses of 300 and 150 mg/kg; levetiracetam – at doses of 100 and 50 mg/kg. Digoxin was administered once subcutaneously at a dose of 0.8 mg/kg body weight (1/10 LD50) 10–15 min before seizure induction. Picrotoxin (aqueous solution 2.5 mg/kg, subcutaneously), thiosemicarbazide (aqueous solution 25 mg/kg, intraperitoneally), strychnine (aqueous solution 1.2 mg/kg, subcutaneously), camphor (oil solution 1000 mg/kg, intraperitoneally) have been used as convulsive agents for seizure induction. It was found that under the conditions of primary generalized seizures induced by picrotoxin, thiosemicarbazide, strychnine, and camphor, digoxin not only shows its own strong anticonvulsant activity but also significantly enhances the anticonvulsant potential of classical AEDs sodium valproate, levetiracetam, and topiramate. The obtained results substantiate the expediency of further in-depth study of digoxin as an anticonvulsant drug, in particular, the in-depth study of neurochemical mechanisms of its action.

Dose-dependent effect of retrieval-extinction on preventing reinstatement of cocaine-associated memory in mice.

As a noninvasive behavioral intervention, the retrieval-extinction (R-E) procedure has drawn much research attention for its capacity to target the reconsolidation of maladaptive memories. However, later research findings suggest that the cause and consequence of R-E may be more complicated than previously suggested. For example, the R-E procedure could increase an animal's motivation for drug-seeking under certain circumstances, and the reversed extinction-retrieval (E-R) procedure could also suppress the drug memory. Two possible mechanisms underlying the R-E procedure have been proposed: the reconsolidation-update and extinction-facilitation hypotheses. To elucidate the paradoxical prior findings and examine these two hypotheses, we systematically examined the efficacy of the extinction (E), R-E, and E-R procedures in mice's low-dose versus high-dose cocaine-induced conditioned place preference (CPP) memory. We showed that the dose of cocaine is a crucial determinant of the efficacy of the three behavioral interventions. The E procedure exerted a long-lasting suppression of the low-dose cocaine CPP memory, while the R-E procedure induced more memory defects than the E and E-R procedures in its long-term suppression of the high-dose cocaine CPP memory. It warrants further investigation of whether the R-E procedure's underlying neurochemical and molecular mechanisms differ from the E and E-R procedures.

Physical Exercise Exerts Neuroprotective Effect on Memory Impairment by Mitigate the Decline of Striatum Catecholamine and Spine Density in a Vascular Dementia Rat Model.

The present study aims to investigate the underlying neurochemical mechanism of physical exercise on striatum synapsis and memory function in vascular dementia model. 32 Sprague-Dawley (SD) rats were randomly divided into 4 groups: control group (C group, n = 6), vascular dementia group (Vascular dementia group, n = 7), physical exercise and vascular dementia group (Exe-VD group, n = 6), physical exercise and black group (Exe group, n = 6). 4weeks of voluntary wheel running were used as pre-exercise training. Vascular dementia model was established by bilateral common carotid arteries occlusion (BCCAo) for 1week. Passive avoidance test (PAT) were used to test memory function. The level of striatum catecholamine in the microdialysate were detected by enzyme linked immunosorbent assy (ELISA). Golgi staining was used to analyze striatum neuronal spine density. Behavioral data indicated that 4weeks of physical exercise ameliorated memory impairment in vascular dementia model. Striatum catecholamine level significantly decreased in VD group when compared with C group (P < .001). But this phenomenon can be rescue by physical exercise (P < .001). In addition, compared with C group, neuronal spine density significantly decreased in VD group (P < .01), but 4weeks of physical exercise can rescue this phenomenon (P < .05). 4weeks of physical exercise improves memory function by mitigate the decline of striatum catecholamine and spine density in VD model.

A Multimodal Examination of Functional Brain and Neurochemical Mechanisms Underlying Nociplastic Pain

A Multimodal Examination of Functional Brain and Neurochemical Mechanisms Underlying Nociplastic Pain

Spinal neurochemical mechanisms of acute stress-induced visceral hypersensitivity in healthy rats

Psychological stress has been demonstrated to increase reports of pain in humans with pelvic pain of urologic origin. In rodent models, conditioning with acute footshock (AFS) has been demonstrated to increase measures of stress/anxiety as well as bladder hypersensitivity. The spinal neurochemical mechanisms of this pro-nociceptive process are unknown and so the present study administered antagonists for multiple receptors that have been associated with facilitatory mechanisms into the spinal intrathecal space. Bladder hypersensitivity was induced through use of an AFS paradigm in which female Sprague-Dawley rats received a 15-min intermittent shock treatment. Visceromotor responses (VMRs; abdominal muscle contractions) to air pressure-controlled urinary bladder distension (UBD) were used as nociceptive endpoints. Immediately following AFS treatments, rats were anesthetized (inhaled isoflurane, IP urethane) and surgically prepared. Pharmacological antagonists were administered via an intrathecal (IT) catheter onto the lumbosacral spinal cord and VMRs to graded UBD determined 15 min later. Administration of IT naloxone hydrochloride (10 μg) and IT phentolamine hydrochloride (10 μg) resulted in VMRs that were more robust than VMRs in rats that received AFS and IT normal saline whereas there was no significant effect of these drugs on VMRs in rats which underwent non-footshock procedures. In contrast, a low dose of the NMDA-receptor antagonist, MK-801 (30 μg), significantly reduced VMRs in rats made hypersensitive to UBD by AFS, but had no significant effect on rats that underwent non-footshock procedures. This study suggests that pro-nociceptive effects of AFS in otherwise healthy rats involve a spinal NMDA-linked mechanism. The effects of IT naloxone and IT phentolamine suggest the presence of inhibitory influences that are opioidergic and/or alpha-adrenergic and that are masked by the pro-nociceptive mechanisms. Other agents with no statistically significant effect on VMRs include methysergide (30 μg), ondansetron (10 μg), mecamylamine (50 μg), antalarmin (24 μg), aSVG30 (12 μg), and SSR149415 (50 μg).

Low-dose digoxin enhances the anticonvulsive potential of carbamazepine and lamotrigine in chemo-induced seizures with different neurochemical mechanisms

"Non-antiepileptic" drugs have a strong potential as adjuvants in multidrug-resistant epilepsy treatment. In previous study the influence of low doses of digoxin, which do not affect the myocardium, on the anticonvulsant potential of classical commonly used anti-epileptic drugs under conditions of seizures, induced by pentylenetetrazole and maximal electroshock, has been investigated.&#x0D; The aim of the study was to investigate the influence of digoxin at a sub-cardiotonic dose on the anticonvulsant potential of carbamazepine and lamotrigine in experimental seizures with different neurochemical mechanisms.&#x0D; Material and methods: A total of 192 random-bred male albino mice weighting 22–25 g were used. Carbamazepine and lamotrigine were administered intragastrically in conditionally effective (ED50) and sub-effective (½ ED50) doses: carbamazepine at doses of 100 and 50 mg/kg; lamotrigine at doses of 25 and 12.5 mg/kg. Digoxin was administered subcutaneously at a sub-cardiotonic dose of 0.8 mg/kg as an adjuvant to carbamazepine and lamotrigine in ½ ED50. Picrotoxin (2.5 mg/kg subcutaneously); thiosemicarbazide (25 mg/kg intraperitoneally); strychnine (1.2 mg/kg subcutaneously); camphor (1000 mg/kg intraperitoneally) were used as convulsant agents.&#x0D; Results: It was found that digoxin not only has its own permanent anticonvulsant effect on different models of paroxysms with different neurochemical mechanisms of development, but also significantly enhances the anticonvulsant potential of carbamazepine (to a lesser extent – lamotrigine) regardless of the pathogenesis of experimental paroxysms.&#x0D; Conclusion: Based on the results, it can be concluded that digoxin has a high potential as an adjuvant medicine in complex epilepsy treatment because it enhances the efficiency of low-dose traditional anticonvulsants carbamazepine and lamotrigine

Dopamine and fear memory formation in the human amygdala

Learning which environmental cues that predict danger is crucial for survival and accomplished through Pavlovian fear conditioning. In humans and rodents alike, fear conditioning is amygdala-dependent and rests on similar neurocircuitry. Rodent studies have implicated a causative role for dopamine in the amygdala during fear memory formation, but the role of dopamine in aversive learning in humans is unclear. Here, we show dopamine release in the amygdala and striatum during fear learning in humans. Using simultaneous positron emission tomography and functional magnetic resonance imaging, we demonstrate that the amount of dopamine release is linked to strength of conditioned fear responses and linearly coupled to learning-induced activity in the amygdala. Thus, like in rodents, formation of amygdala-dependent fear memories in humans seems to be facilitated by endogenous dopamine release, supporting an evolutionary conserved neurochemical mechanism for aversive memory formation.

P.0621 What renders people vulnerable to developing opioid addiction?

In non-human primates, opioid-receptor blockade increases social grooming, and the endogenous opioid system has therefore been hypothesized to support maintenance of long-term relationships in humans as well. Here we tested whether social touch modulates opioidergic activation in humans using in vivo positron emission tomography (PET). Eighteen male participants underwent two PET scans with [11C]carfentanil, a ligand specific to μ-opioid receptors (MOR). During the social touch scan, the participants lay in the scanner while their partners caressed their bodies in a non-sexual fashion. In the baseline scan, participants lay alone in the scanner. Social touch triggered pleasurable sensations and increased MOR availability in the thalamus, striatum, and frontal, cingulate, and insular cortices. Modulation of activity of the opioid system by social touching might provide a neurochemical mechanism reinforcing social bonds between humans.

Neuromolecular Underpinnings of Negative Cognitive Bias in Depression.

This selective review aims to summarize the recent advances in understanding the neuromolecular underpinnings of biased cognition in depressive disorder. We begin by considering the cognitive correlates of depressed mood and the key brain systems implicated in its development. We then review the core findings across two domains of biased cognitive function in depression: pessimistic judgment bias and abnormal response to negative feedback. In considering their underlying substrates, we focus on the neurochemical mechanisms identified by genetic, molecular and pharmacological challenge studies. We conclude by discussing experimental approaches to the treatment of depression, which are derived largely from an improved understanding of its cognitive substrates.

Morphological analysis of the brain subcortical gray structures in restless legs syndrome

BackgroundAlthough several studies have shown the involvement of specific structures of the central nervous system, the dopaminergic system, and iron metabolism in restless legs syndrome (RLS), the exact location and extent of its anatomical substrate is not yet known. The scope of this new study was to investigate the brain subcortical gray structures, by means of structural magnetic resonance imaging (MRI) studies, in RLS patients in order to assess the presence of any volume or shape abnormalities involving these structures. MethodsThirty-three normal controls (24 females and nine males) and 45 RLS patients (34 females and 11 males) were retrospectively recruited and underwent a 1.5 Tesla MRI study with two-dimensional T1 sequences in the sagittal plane. Post-processing was performed by means of the Functional Magnetic Resonance Imaging of the Brain Analysis Group Integrated Registration and Segmentation Tool (FIRST) software, and both volumetric and morphological analyses of the thalamus, caudate, putamen, globus pallidus, brainstem, hippocampus, and amygdala, bilaterally, were carried out. ResultsA statistically significant volumetric reduction in the left amygdala and left globus pallidus was found in subjects with RLS, as well as large surface morphological alterations affecting the amygdala bilaterally and other less widespread surface changes in both hippocampi, the right caudate, the left globus pallidus, and the left putamen. ConclusionsThese findings seem to indicate that the basic mechanisms of RLS might include a pathway involving not only the hypothalamus-spinal dopaminergic circuit (nucleus A11), but also pathways including the basal ganglia and structures that are part of the limbic system; moreover, structural alterations in RLS seem to concern the morphology as well as the volume of the above structures. The role of basal ganglia in the complex neurophysiological and neurochemical mechanism of RLS needs to carefully reconsidered.

NEUROPSYCHOLOGICAL ANALYSIS OF THE NEUROTICISM NATURE: EVIDENCE FOR A HETEROGENEITY OF CONSTRUCT

This work is devoted to the neuropsychological study of personality traits from the point of view of "Big Five" model of personality. The focus is on neuroticism and its neuropsychological correlates in the broader context of the neuroscience. The data on the genetics of neuroticism, the results of neuroimaging studies, and the neurochemical mechanisms of this trait are analyzed. It has been shown that neuroticism as a neuropsychological construct has a heterogeneous structure: an analysis of numerous studies makes it possible to distinguish two relatively independent types of neuroticism, which are associated with specific types of adaptation and different "modus vivendi". Two aspects of neuroticism (according to C.G. DeYoung), such as "volatility" and "withdrawal", from the point of view of genetics, correspond to two endophenotypes: "depressed affect" and "worry". So the processing of aversive stimuli in people with a "volatile" type of neuroticism is mainly manifested in the form of active avoidance of the source of danger, which takes the form of irritability and moodiness. The leading emotional problematic for such people concerns loneliness. The neural circuits that are overactive in this type of neuroticism affect the limbic system, in particular the amygdala. In EEG studies, the role of the left hemisphere, mainly of its frontal regions, has also been established. There is a connection between this aspect and impulsivity, which manifests itself in bad habits, patterns of reproductive and eating behavior. In turn, the "withdrawn" type demonstrates a tendency towards passive avoidance of the source of unpleasant experiences, poverty of expression, and perfectionism. Mental maladjustment takes the form of detachment, "freezing", practices that indicate emotional decompensation are concerns about the correctness of their decisions and actions. The neural circuits that mediate these behavioral patterns bypass the amygdala and engage the cortico-striato-thalamo-cortical loop. EEG studies also revealed the right hemispheric accent of this type of neuroticism. A connection is traced between the psychogenetics of neuroticism, neuropsychological models of the personality trait of neuroticism (as well as its aspects: lability and alienation), as well as the types of defenses against the fear of death, which are offered in the existential approach (by Irwin Yalom). Thus, it seems reasonable to distinguishing two different types of neuroticism, which have an independent genetic origin and a different psychological nature.

Why It Is Important to Consider the Effects of Analgesics on Sleep: A Critical Review.

We review the known physiological mechanisms underpinning all of pain processing, sleep regulation, and pharmacology of analgesics prescribed for chronic pain. In particular, we describe how commonly prescribed analgesics act in sleep-wake neural pathways, with potential unintended impact on sleep and/or wake function. Sleep disruption, whether pain- or drug-induced, negatively impacts quality of life, mental and physical health. In the context of chronic pain, poor sleep quality heightens pain sensitivity and may affect analgesic function, potentially resulting in further analgesic need. Clinicians already have to consider factors including efficacy, abuse potential, and likely side effects when making analgesic prescribing choices. We propose that analgesic-related sleep disruption should also be considered. The neurochemical mechanisms underlying the reciprocal relationship between pain and sleep are poorly understood, and studies investigating sleep in those with specific chronic pain conditions (including those with comorbidities) are lacking. We emphasize the importance of further work to clarify the effects (intended and unintended) of each analgesic class to inform personalized treatment decisions in patients with chronic pain. © 2021 American Physiological Society. Compr Physiol 11:1-31, 2021.

Positron emission tomography imaging of serotonin degeneration and beta-amyloid deposition in late-life depression evaluated with multi-modal partial least squares

Depression in late-life is associated with increased risk of cognitive decline and development of all-cause dementia. The neurobiology of late-life depression (LLD) may involve both neurochemical and neurodegenerative mechanisms that are common to depression and dementia. Transgenic amyloid mouse models show evidence of early degeneration of monoamine systems. Informed by these preclinical data, the hypotheses were tested that a spatial covariance pattern of higher beta-amyloid (Aβ) and lower serotonin transporter availability (5-HTT) in frontal, temporal, and parietal cortical regions would distinguish LLD patients from healthy controls and the expression of this pattern would be associated with greater depressive symptoms. Twenty un-medicated LLD patients who met DSM-V criteria for major depression and 20 healthy controls underwent PET imaging with radiotracers for Aβ ([11C]-PiB) and 5-HTT ([11C]-DASB). A voxel-based multi-modal partial least squares (mmPLS) algorithm was applied to the parametric PET images to determine the spatial covariance pattern between the two radiotracers. A spatial covariance pattern was identified, including higher Aβ in temporal, parietal and occipital cortices associated with lower 5-HTT in putamen, thalamus, amygdala, hippocampus and raphe nuclei (dorsal, medial and pontine), which distinguished LLD patients from controls. Greater expression of this pattern, reflected in summary 5-HTT/Aβ mmPLS subject scores, was associated with higher levels of depressive symptoms. The mmPLS method is a powerful approach to evaluate the synaptic changes associated with AD pathology. This spatial covariance pattern should be evaluated further to determine whether it represents a biological marker of antidepressant treatment response and/or cognitive decline in LLD patients.

The critical period: neurochemical and synaptic mechanisms shared by the visual cortex and the brain stem respiratory system.

The landmark studies of Wiesel and Hubel in the 1960's initiated a surge of investigations into the critical period of visual cortical development, when abnormal visual experience can alter cortical structures and functions. Most studies focused on the visual cortex, with relatively little attention to subcortical structures. The goal of the present review is to elucidate neurochemical and synaptic mechanisms common to the critical periods of the visual cortex and the brain stem respiratory system in the normal rat. In both regions, the critical period is a time of (i) heightened inhibition; (ii) reduced expression of brain-derived neurotrophic factor (BDNF); and (iii) synaptic imbalance, with heightened inhibition and suppressed excitation. The last two mechanisms are contrary to the conventional premise. Synaptic imbalance renders developing neurons more vulnerable to external stressors. However, the critical period is necessary to enable each system to strengthen its circuitry, adapt to its environment, and transition from immaturity to maturity, when a state of relative synaptic balance is attained. Failure to achieve such a balance leads to neurological disorders.

Differential effects of memory enhancing and impairing doses of methylphenidate on serotonin metabolism and 5-HT1A, GABA, glutamate receptor expression in the rat prefrontal cortex

Methylphenidate (MPD), a psychostimulant, is a prescription medicine for treating attention deficit hyperactivity disorder (ADHD). Previously we have shown that moderate doses of MPD enhanced learning and memory while higher doses impaired it. To understand neurochemical mechanisms and receptors involved in memory enhancing and impairing effects of MPD, the present study concerns the effects of these doses of MPD on serotonin, 5-HT1A, GABA, and NMDA receptor mRNA expression in the prefrontal cortex (PFC). We found that low doses (2.5 mg/kg) of MPD improved performance in the water-maze test but higher doses (5 mg/kg) impaired memory retention. Animals showing improved performance had high 5-HT metabolism in the PFC while these levels were not affected in the group treated with higher MPD doses and exhibiting impaired memory. There was downregulation of 5-HT1A receptors in the PFC of rats treated with higher dose MPD, which didn't occur in low dose of MPD treated animals. Further, a decrease in GABAAreceptor mRNA expression occurred in low doses of MPD treated animals and GluN2A expression was reduced in higher doses of MPD treated animals. The findings suggest that memory enhancing doses of MPD increase 5-HT and reduce GABAA receptor mRNA expression in the PFC to release excitatory glutamate neurons from the inhibitory influence of GABA. Conversely, higher dose of MPD downregulates 5-HT1A receptor mRNA expression to enhance inhibitory GABA influence on glutamate neurons and impair cognitive performance. The findings show an important role of 5-HT1A heteroreceptors in the PFC for improving therapeutic use of MPD and developing novel cognitive enhancers.

The Brain Metabolic Signature in Superagers Using In Vivo 1H-MRS: A Pilot Study.

Youthful memory performance in older adults may reflect an underlying resilience to the conventional pathways of aging. Subjects having this unusual characteristic have been recently termed "superagers." This study aimed to explore the significance of imaging biomarkers acquired by 1H-MRS to characterize superagers and to differentiate them from their normal-aging peers. Fifty-five patients older than 80 years of age were screened using a detailed neuropsychological protocol, and 25 participants, comprising 12 superagers and 13 age-matched controls, were statistically analyzed. We used state-of-the-art 3T 1H-MR spectroscopy to quantify 18 neurochemicals in the posterior cingulate cortex of our subjects. All 1H-MR spectroscopy data were analyzed using LCModel. Results were further processed using 2 approaches to investigate the technique accuracy: 1) comparison of the average concentration of metabolites estimated with Cramer-Rao lower bounds <20%; and 2) calculation and comparison of the weighted means of metabolites' concentrations. The main finding observed was a higher total N-acetyl aspartate concentration in superagers than in age-matched controls using both approaches (P = .02 and P = .03 for the weighted means), reflecting a positive association of total N-acetyl aspartate with higher cognitive performance. 1H-MR spectroscopy emerges as a promising technique to unravel neurochemical mechanisms related to cognitive aging in vivo and providing a brain metabolic signature in superagers. This may contribute to monitoring future interventional therapies to avoid or postpone the pathologic processes of aging.

The Sugars in Alcohol Cocktails Matter.

While sugar consumption and alcohol drinking have traditionally been studied by different basic science fields, most commercially available flavored alcoholic beverages are sweetened with some kind of sugar. The prevailing view is that these sugars potentiate drinking by making the alcohol taste better, particularly for adolescents, overlooking that some central nervous system circuits implicated in alcohol drinking are also sensitive to brain penetrant sugars like glucose. In this Viewpoint, we highlight the need for basic researchers to carefully consider how the sugars mixed with alcoholic beverages may impact the neurochemical and biological mechanisms influencing alcohol drinking and the development of alcohol use disorder.