Variations in Acetylcholinesterase Activity within Human Cortical Pyramidal Neurons Across Age and Cognitive Trajectories

Juvenile bright light exposure ameliorates adult behavioral abnormalities by enhancing neurogenesis in a N-methyl-D-aspartate receptor dysfunction mouse model relevant for cognitive impairment in schizophrenia

Exposure to light has been demonstrated to stimulate brain regions associated with cognition; however, investigations into its cognitive-enhancing effects have primarily focused on wild-type rodents. This study seeks to elucidate how bright light exposure mitigates cognitive deficits associated with schizophrenia by examining its impact on hippocampal neurogenesis and its potential to alleviate sub-chronic MK-801-induced cognitive impairments in mice. Following three weeks of juvenile bright light exposure (5-8 weeks old), significant increases in proliferating neurons (BrdU+) and immature neurons (DCX+ cells) were observed in the dentate gyrus (DG) and lateral ventricle of MK-801-treated mice. Long-term bright light treatment further promoted the differentiation of BrdU+ cells into immature neurons (BrdU+ DCX+ cells), mature neurons (BrdU+ NeuN+ cells), or astrocytes (BrdU+ GFAP+ cells) in the hippocampal DG. This augmented neurogenesis correlated with the attenuation of sub-chronic MK- 801-induced cognitive deficits, as evidenced by enhancements in Y-maze, novel object recognition (NOR), novel location recognition (NLR), and Morris water maze (MWM) test performances. These findings suggest a promising noninvasive clinical approach for alleviating cognitive impairments associated with neuropsychiatric disorders.

Cognitively high-performing oldest old individuals are physically active and have strong motor skills-A study of the Danish 1905 and 1915 birth cohorts

Preserving cognitive function with age or super-aging greatly contributes to successful aging. Super-aging nonagenarians born in Denmark in either year 1905 or 1915 were classified as Cognitively High-Performing Oldest Old individuals with a five item cognitive composite score, equivalent to or better than mean middle-aged subjects. Cognitively high-performers were more physically active and had a better physical performance on e.g., Activity of Daily Living (p-value < 0.01), gait speed (p-value < 0.01) and grip strength (p-value < 0.05) compared with age-matched peers. Cognitive high-performing was also linked to lower depression symptomatology. When comparing super-agers with semi super-agers classified by Mini Mental State Examination > 27, super-agers were still more physically active and had a better physical performance (p-value < 0.05). Results suggests that physical activity is a lifestyle factor strongly associated with both semi and full cognitive super-aging.

Nanoencapsulated Curcumin: Enhanced Efficacy in Reversing Memory Loss in An Alzheimer Disease Model

Investigating new drugs or formulations that target Alzheimer disease (AD) is critical for advancing therapeutic interventions. Therefore, this study aimed to assess the effectiveness of nanoencapsulated curcumin (NC Curc) in alleviating memory impairment, oxidative stress, and neuroinflammation in a validated AD model. Male Wistar rats were given bilateral intracerebroventricular injections of either saline or streptozotocin (STZ) (3 mg/3 µL/site) to establish the AD model (day 0). On day 22, daily oral administrations of curcumin (6 mg/kg), NC Curc (6 mg/kg), or a vehicle (unloaded NC) were initiated and continued for 14 days. NC Curc significantly reversed memory deficits in object recognition and inhibitory avoidance tests induced by STZ. Both formulations of curcumin attenuated elevated acetylcholinesterase activity caused by STZ. Importantly, NC Curc alone effectively mitigated STZ-induced oxidative stress. Additionally, NC Curc treatment normalized GFAP levels, suggesting a potential reduction in neuroinflammation in STZ-treated rats. Our findings indicate that NC Curc improves memory in an AD rat model, highlighting its enhanced therapeutic effects compared to unencapsulated curcumin. This research significantly contributes to understanding the therapeutic and neurorestorative potential of NC Curc in AD, particularly in reversing pathophysiological changes.

Alzheimer's Disease in Lebanon: Exploring Genetic and Environmental Risk Factors-A Comprehensive Review

Alzheimer's disease (AD) is a neurodegenerative condition that displays a high prevalence in Lebanon causing a local burden in healthcare and socio-economic sectors. Unfortunately, the lack of prevalence studies and clinical trials in Lebanon minimizes the improvement of AD patient health status. In this review, we include over 155 articles to cover the different aspects of AD ranging from mechanisms to possible treatment and management tools. We highlight some important modifiable and non-modifiable risk factors of the disease including genetics, age, cardiovascular diseases, smoking, etc. Finally, we propose a hypothetical genetic synergy model between APOE4 and TREM2 genes which constitutes a potential early diagnostic tool that helps in reducing the risk of AD based on preventative measures decades before cognitive decline. The studies on AD in Lebanon and the Middle East are scarce. This review points out the importance of genetic mapping in the understanding of disease pathology which is crucial for the emergence of novel diagnostic tools. Hence, we establish a rigid basis for further research to identify the most influential genetic and environmental risk factors for the purpose of using more specific diagnostic tools and possibly adopting a local management protocol.

Defining exceptional cognition in older adults: A systematic review of cognitive super-ageing

OBJECTIVE

A consistent approach to defining cognitive super-ageing is needed to increase the value of research insights that may be gained from studying this population including ageing well and preventing and treating neurodegenerative conditions. This review aims to evaluate the existing definitions of 'super-ageing' with a focus on cognition.

METHODS

A systematic literature search was conducted across PubMed, Embase, Web of Science, Scopus, PsycINFO and Google Scholar from inception to 24 July 2023.

RESULTS

Of 44 English language studies that defined super-ageing from a cognitive perspective in older adults (60-97 years), most (n = 33) were based on preserved verbal episodic memory performance comparable to that of younger adult in age range 16-65 years. Eleven studies defined super-agers as the top cognitive performers for their age group based upon standard deviations or percentiles above the population mean. Only nine studies included longitudinal cognitive performance in their definitions.

CONCLUSIONS

Equivalent cognitive abilities to younger adults, exceptional cognition for age and a lack of cognitive deterioration over time are all meaningful constructs and may provide different insights into cognitive ageing. Using these criteria in combination or individually to define super-agers, with a clear rationale for which elements have been selected, could be fit for purpose depending on the research question. However, major discrepancies including the age range of super-agers and comparator groups and the choice of cognitive domains assessed should be addressed to reach some consensus in the field.

Frequency of cognitive "super-aging" in three Australian samples using different diagnostic criteria

OBJECTIVES

To investigate the frequency of exceptional cognition (cognitive super-aging) in Australian older adults using different published definitions, agreement between definitions, and the relationship of super-aging status with function, brain imaging markers, and incident dementia.

DESIGN

Three longitudinal cohort studies.

SETTING

Participants recruited from the electoral roll, Australian Twins Registry, and community advertisements.

PARTICIPANTS

Older adults (aged 65-106) without dementia from the Sydney Memory and Ageing Study (n = 1037; median age 78), Older Australian Twins Study (n = 361; median age 68), and Sydney Centenarian Study (n = 217; median age 97).

MEASUREMENTS

Frequency of super-aging was assessed using nine super-aging definitions based on performance on neuropsychological testing. Levels of agreement between definitions were calculated, and associations between super-aging status for each definition and functioning (Bayer ADL score), structural brain imaging measures, and incident dementia were explored.

RESULTS

Frequency of super-aging varied between 2.9 and 43.4 percent with more stringent definitions associated with lower frequency. Agreement between different criteria varied from poor (K = 0.04, AC1 = .24) to very good (K = 0.83, AC1 = .91) with better agreement between definitions using similar tests and cutoffs. Super-aging was associated with better functional performance (4.7-11%) and lower rates of incident dementia (hazard ratios 0.08-0.48) for most definitions. Super-aging status was associated with a lower burden of white matter hyperintensities (3.8-33.2%) for all definitions.

CONCLUSIONS

The frequency of super-aging is strongly affected by the demographic and neuropsychological testing parameters used. Greater consistency in defining super-aging would enable better characterization of this exceptional minority.

Brain structure and phenotypic profile of superagers compared with age-matched older adults: a longitudinal analysis from the Vallecas Project

BACKGROUND

Cognitive abilities, particularly memory, normally decline with age. However, some individuals, often designated as superagers, can reach late life with the memory function of individuals 30 years younger. We aimed to characterise the brain structure of superagers and identify demographic, lifestyle, and clinical factors associated with this phenotype.

METHODS

We selected cognitively healthy participants from the Vallecas Project longitudinal cohort recruited between Oct 10, 2011, and Jan 14, 2014, aged 79·5 years or older, on the basis of their delayed verbal episodic memory score. Participants were assessed with the Free and Cued Selective Reminding Test and with three non-memory tests (the 15-item version of the Boston Naming Test, the Digit Symbol Substitution Test, and the Animal Fluency Test). Participants were classified as superagers if they scored at or above the mean values for a 50-56-year-old in the Free and Cued Selective Reminding Test and within one standard deviation of the mean or above for their age and education level in the three non-memory tests, or as typical older adults if they scored within one standard deviation of the mean for their age and education level in the Free and Cued Selective Reminding Test. Data acquired as per protocol from up to six yearly follow-ups were used for longitudinal analyses.

FINDINGS

We included 64 superagers (mean age 81·9 years; 38 [59%] women and 26 [41%] men) and 55 typical older adults (82·4 years; 35 [64%] women and 20 [36%] men). The median number of follow-up visits was 5·0 (IQR 5·0-6·0) for superagers and 5·0 (4·5-6·0) for typical older adults. Superagers exhibited higher grey matter volume cross-sectionally in the medial temporal lobe, cholinergic forebrain, and motor thalamus. Longitudinally, superagers also showed slower total grey matter atrophy, particularly within the medial temporal lobe, than did typical older adults. A machine learning classification including 89 demographic, lifestyle, and clinical predictors showed that faster movement speed (despite no group differences in exercise frequency) and better mental health were the most differentiating factors for superagers. Similar concentrations of dementia blood biomarkers in superager and typical older adult groups suggest that group differences reflect inherent superager resistance to typical age-related memory loss.

INTERPRETATION

Factors associated with dementia prevention are also relevant for resistance to age-related memory decline and brain atrophy, and the association between superageing and movement speed could provide potential novel insights into how to preserve memory function into the ninth decade.

FUNDING

Queen Sofia Foundation, CIEN Foundation, Spanish Ministry of Science and Innovation, Alzheimer's Association, European Research Council, MAPFRE Foundation, Carl Zeiss Foundation, and the EU Comission for Horizon 2020.

TRANSLATION

For the Spanish translation of the abstract see Supplementary Materials section.

Barbigerone prevents scopolamine-induced memory impairment in rats by inhibiting oxidative stress and acetylcholinesterase levels

The current study was designed for the evaluation of barbigerone on memory loss. In this experimental study, 24 Wistar rats (n = 6) were used. Control rats and scopolamine (SCOP)-treated control group rats were orally administered with 3 ml of 0.5% sodium carboxymethyl cellulose (vehicle), whereas barbigerone was (10 and 20 mg kg^-1) administered orally to the rats from the test group. During the 14-day treatment, control group rats were given 3 ml kg^-1 day^-1 saline, and all other groups were administered SCOP (1 mg kg^-1 day^-1, i.p.) 1 h after barbigerone p.o. treatment. The spontaneous alternation activities, learning capacities of a rat's memory were tested with Morris water maze and Y-maze. Reduced glutathione, malondialdehyde, acetylcholine esterase (AChE) and catalase (CAT) levels were measured in rat brain tissue as oxidative stress/antioxidant markers. Moreover, the levels of tumour necrosis factor, interleukin-6 (IL-6) and IL-1β were also estimated. Treatment with barbigerone in SCOP-administered rats dramatically reduced SCOP-induced neurobehavioural deficits, oxidative stress and neuroinflammatory markers, improved endogenous antioxidants, and restored AChE activity. By improving cholinergic function and reducing oxidative damage, barbigerone could mitigate the effects of SCOP-induced changes in the brain.

Xanomeline restores endogenous nicotinic acetylcholine receptor signaling in mouse prefrontal cortex

Cholinergic synapses in prefrontal cortex are vital for attention, but this modulatory system undergoes substantial pre- and post-synaptic alterations during adulthood. To examine the integrated impact of these changes, we optophysiologically probe cholinergic synapses ex vivo, revealing a clear decline in neurotransmission in middle adulthood. Pharmacological dissection of synaptic components reveals a selective reduction in postsynaptic nicotinic receptor currents. Other components of cholinergic synapses appear stable, by contrast, including acetylcholine autoinhibition, metabolism, and excitation of postsynaptic muscarinic receptors. Pursuing strategies to strengthen cholinergic neurotransmission, we find that positive allosteric modulation of nicotinic receptors with NS9283 is effective in young adults but wanes with age. To boost nicotinic receptor availability, we harness the second messenger pathways of the preserved excitatory muscarinic receptors with xanomeline. This muscarinic agonist and cognitive-enhancer restores nicotinic signaling in older mice significantly, in a muscarinic- and PKC-dependent manner. The rescued nicotinic component regains youthful sensitivity to allosteric enhancement: treatment with xanomeline and NS9283 restores cholinergic synapses in older mice to the strength, speed, and receptor mechanism of young adults. Our results reveal a new and efficient strategy to rescue age-related nicotinic signaling deficits, demonstrating a novel pathway for xanomeline to restore cognitively-essential endogenous cholinergic neurotransmission.

Neuroprotective Effect of Barbaloin on Streptozotocin-Induced Cognitive Dysfunction in Rats via Inhibiting Cholinergic and Neuroinflammatory Cytokines Pathway-TNF-α/IL-1β/IL-6/NF-κB

Streptozotocin (STZ) impairs memory in rats through altering the central nervous systems (CNS) as a result of impaired cholinergic dysfunction, oxidative stress, persistent hyperglycemia, and alterations in the glucagon-like peptide (GLP). In this model cholinergic agonist, antioxidant and antihyperglycemic treatment has been shown to have positive effects. Barbaloin has a variety of pharmacological effects. However, there is no evidence on how barbaloin improves memory dysfunction caused by STZ. Thus, we examined its effectiveness against cognitive damage caused by STZ at a dose of 60 mg/kg i.p. in Wistar rats. Blood glucose levels (BGL) and body weight (BW) were assessed. To assess learning and memory skills, the Y-maze test and Morris water maze (MWM) test were utilized. Superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), and glutathione (GSH) as oxidative stress markers were regulated to reverse the cognitive deterioration, and choline-acetyltransferase (ChAT) and acetyl-cholinesterase (AChE) as indicators of cholinergic dysfunction, nuclear factor kappa-B (NF-κB), IL-1β (interleukin-1β), IL-6, and tumor necrosis factor-α (TNF-α) contents were used. Barbaloin treatment thereby significantly decreased the BW and learning and memory capacities, resulting in substantial behavioral improvement in the Y-maze and MWM test. BGL, SOD, CAT, MDA, GSH, AChE, ChAT, NF-κB, IL-6, TNF-α, and IL-1β levels were also altered. In conclusion, the findings revealed that barbaloin had a protective impact against cognitive dysfunction caused by STZ.

Honey and Alzheimer's Disease-Current Understanding and Future Prospects

Alzheimer's disease (AD), a leading cause of dementia, has been a global concern. AD is associated with the involvement of the central nervous system that causes the characteristic impaired memory, cognitive deficits, and behavioral abnormalities. These abnormalities caused by AD is known to be attributed by extracellular aggregates of amyloid beta plaques and intracellular neurofibrillary tangles. Additionally, genetic factors such as abnormality in the expression of APOE, APP, BACE1, PSEN-1, and PSEN-2 play a role in the disease. As the current treatment aims to treat the symptoms and to slow the disease progression, there has been a continuous search for new nutraceutical agent or medicine to help prevent and cure AD pathology. In this quest, honey has emerged as a powerful nootropic agent. Numerous studies have demonstrated that the high flavonoids and phenolic acids content in honey exerts its antioxidant, anti-inflammatory, and neuroprotective properties. This review summarizes the effect of main flavonoid compounds found in honey on the physiological functioning of the central nervous system, and the effect of honey intake on memory and cognition in various animal model. This review provides a new insight on the potential of honey to prevent AD pathology, as well as to ameliorate the damage in the developed AD.

Integrity of Neuronal Size in the Entorhinal Cortex Is a Biological Substrate of Exceptional Cognitive Aging

Average aging is associated with a gradual decline of memory capacity. SuperAgers are humans ≥80 years of age who show exceptional episodic memory at least as good as individuals 20-30 years their junior. This study investigated whether neuronal integrity in the entorhinal cortex (ERC), an area critical for memory and selectively vulnerable to neurofibrillary degeneration, differentiated SuperAgers from cognitively healthy younger individuals, cognitively average peers ("Normal Elderly"), and individuals with amnestic mild cognitive impairment. Postmortem sections of the ERC were stained with cresyl violet to visualize neurons and immunostained with mouse monoclonal antibody PHF-1 to visualize neurofibrillary tangles. The cross-sectional area (i.e., size) of layer II and layer III/V ERC neurons were quantified. Two-thirds of total participants were female. Unbiased stereology was used to quantitate tangles in a subgroup of SuperAgers and Normal Elderly. Linear mixed-effect models were used to determine differences across groups. Quantitative measurements found that the soma size of layer II ERC neurons in postmortem brain specimens were significantly larger in SuperAgers compared with all groups (p < 0.05)-including younger individuals 20-30 years their junior (p < 0.005). SuperAgers had significantly fewer stereologically quantified Alzheimer's disease-related neurofibrillary tangles in layer II ERC than Normal Elderly (p < 0.05). This difference in tangle burden in layer II between SuperAgers and Normal Elderly suggests that tangle-bearing neurons may be prone to shrinkage during aging. The finding that SuperAgers show ERC layer II neurons that are substantially larger even compared with individuals 20-30 years younger is remarkable, suggesting that layer II ERC integrity is a biological substrate of exceptional memory in old age.SIGNIFICANCE STATEMENT Average aging is associated with a gradual decline of memory. Previous research shows that an area critical for memory, the entorhinal cortex (ERC), is susceptible to the early formation of Alzheimer's disease neuropathology, even during average (or typical) trajectories of aging. The Northwestern University SuperAging Research Program studies unique individuals known as SuperAgers, individuals ≥80 years old who show exceptional memory that is at least as good as individuals 20-30 years their junior. In this study, we show that SuperAgers harbor larger, healthier neurons in the ERC compared with their cognitively average same-aged peers, those with amnestic mild cognitive impairment, and - remarkably - even compared with individuals 20-30 years younger. We conclude that larger ERC neurons are a biological signature of the SuperAging trajectory.

Butin Mitigates Memory Impairment in Streptozotocin-Induced Diabetic Rats by Inhibiting Oxidative Stress and Inflammatory Responses

It has been reported from the previous literature that butin restores mitochondrial dysfunction by modulation of oxidative stress and glutamate-induced neurotoxicity in mouse hippocampus HT22 cells. Butin also possesses an anti-Huntington's effect in rats. Considering the current background, this study was designed to evaluate the neuroprotective effect of butin against memory loss caused by streptozotocin (STZ). STZ (40 mg/kg) was intraperitoneally injected into rats. Three days later, diabetic rats were identified and included in the study. A total of 30 rats (12 nondiabetic and 18 diabetics) were grouped as Group A (control-non-diabetic rats) and Group B (STZ diabetic control) were treated with 1 mL of sodium CMC (0.5% w/v). Group C (STZ+ butin 25) were treated with butin 25 mg/kg. Group D (STZ+ butin 50) and Group E (butin per se) were administered with butin 50 mg/kg. Each therapy was administered orally once each day for 15-day. The Morris water maze and the Y-maze behavioural tests were run throughout the experimental programme. Animals were put to death on day 15 and their brains were removed for biochemical assays (CAT, SOD, GSH, MDA, nitrite, acetylcholinesterase (AchE), IL-1, and mitochondrial enzyme complexes). Rats with neurobehavioral impairments brought on by STZ have less spontaneous movement, learning capacity, and memory. Additionally, STZ decreased endogenous antioxidants and increased pro-inflammatory cytokines, nitrite, MDA, and AchE. Neurobehavioral deficits and metabolic markers were dramatically improved by butin.

Rosiridin Attenuates Scopolamine-Induced Cognitive Impairments in Rats via Inhibition of Oxidative and Nitrative Stress Leaded Caspase-3/9 and TNF-α Signaling Pathways

AIM

A monoterpene and bioactive component of the plant Rhodiola rosea (R. rosea), rosiridin has beneficial effects on the human central nervous system and enhances brain function. The goal of this scientific study was to determine if rosiridin might shield rats from neurocognitive problems induced by scopolamine.

METHODS

To track the potential toxicities in rats, the acute toxicity in rats was clarified. Rosiridin at a dose of 10 mg/kg was tested in rats for 14 days. At the conclusion of the investigation, behavioral parameters that were used to identify the rats' cognitive and motor abilities were evaluated. Several biochemical parameters were estimated using the prepared homogenate, including acetylcholine esterase (AChE), choline acetyltransferase (ChAT), radical scavengers produced by the body (Catalase-CAT, superoxide dismutase-SOD, and reduced glutathione-GSH), indicators of oxidative and nitrative burnout, pro-inflammatory (Interleukins- IL-1β, IL-6, interferon gamma IFN-ꝩ, and tumor necrosis factor-TNF-α), and cell apoptosis caspases 3 and 9.

RESULTS AND CONCLUSION

A significant behavioral parameter restoration was seen in the rosiridin-treated group, including reduction in latency time during acquisition and retention trial in the Morris water maze test, and percentage of spontaneous alterations in the y-maze test, when compared to the disease control group that received scopolamine; rosiridin also altered the oxidative stress and neuroinflammatory markers, as well as restoring Ach and ChAT activities and normalizing GSH, SOD, MDA, TNF-α, nitrate, IL-1β, IL-6, IFN-ꝩ, caspases 3 and 9 levels. The results imply that rosiridin limits the effect of scopolamine on rat cognitive function.

Neuropathology and cholinesterase expression in the brains of octogenarians and older

A subset of octogenarians and older maintain normal cognitive function (CNOO) despite high prevalence and incidence of cognitive decline attributed to neurodegeneration or aging in the population. The rostral prefrontal cortex (rPFC) and hippocampal formation are brain regions integral to cognition, namely attention and memory, facilitated in part by cholinergic innervation. We hypothesized that preserved cholinergic neurotransmission in these regions contributes to intact cognition in the CNOO. To test this, we evaluated the burden of neuropathological and cholinesterase-associated protein aggregates in the rPFC and hippocampal formation. Tissues from age- and sex-matched CNOO and Alzheimer's disease (AD) rPFC and hippocampal formation were stained for β-amyloid (Aβ), tau, α-synuclein, phosphorylated TAR DNA-binding protein 43 (pTDP-43), acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). The relative abundance of neuropathological aggregates was semi-quantitatively scored. Deposition of Aβ plaques, tau neurofibrillary tangles (NFT) and pTDP-43 inclusions were comparable between CNOO and AD cases. Intraneuronal Aβ and tau-positive thorny astrocytes consistent with aging-related tau astrogliopathy, were also noted in the rPFC. Abundance of BChE-positive plaque pathology was significantly higher in AD than in CNOO cases in most regions of interest, followed closely by abundance of AChE-positive plaque pathology. BChE- and AChE-activities were also associated with varied NFT morphologies. CNOO cases maintained cognition despite a high neuropathological burden in the rPFC and hippocampal formation. BChE-positive and, to a lesser extent, AChE-positive pathologies were significantly lower in most regions in the CNOO compared to AD. This suggests a specificity of cholinesterase-associated neuropathology with AD. We conclude that while CNOO have cholinesterase-associated neuropathology in the rPFC and hippocampal formation, abundance in this population is significantly lower compared to AD which may contribute to their intact cognition.

Choline intake effects on psychophysiological indicators of students in the pre-exam period

Introduction. Choline has a wide range of physiological functions. It has a neuroprotective effect on brain dysfunctions, while its deficiency has a negative effect on antenatal development of the nervous system. We aimed to study the impact of exogenous choline on the psychophysiological indicators in students. Study objects and methods. 87 students were surveyed by questionnaire to determine their background intake of dietary choline. One month before the exams, we measured their simple and complex visual-motor reaction times, functional mobility and balance of nervous processes, as well as indicators of their short-term memory, attention, health, activity, and mood. Then, we divided the students into a control and an experimental group, regardless of their choline intake. The experimental group took 700 mg choline supplements on a daily basis for one month, followed by a second psychophysiological examination. Results and discussion. Students with a low choline intake had lower functional mobility and balance of nervous processes, but better attention stability than students with a high choline intake. The second examination showed improved short-term memory, health, and activity indicators in the experimental group, compared to the control. The visual-motor reaction times also increased, but only in students with an initially low level of choline intake. Conclusion. Choline supplementation can be recommended to students under pre-exam stress to enhance the functional state of their central nervous system.

Basal forebrain cholinergic system in the dementias: Vulnerability, resilience, and resistance

The basal forebrain cholinergic neurons (BFCN) provide the primary source of cholinergic innervation of the human cerebral cortex. They are involved in the cognitive processes of learning, memory, and attention. These neurons are differentially vulnerable in various neuropathologic entities that cause dementia. This review summarizes the relevance to BFCN of neuropathologic markers associated with dementias, including the plaques and tangles of Alzheimer's disease (AD), the Lewy bodies of diffuse Lewy body disease, the tauopathy of frontotemporal lobar degeneration (FTLD-TAU) and the TDP-43 proteinopathy of FTLD-TDP. Each of these proteinopathies has a different relationship to BFCN and their corticofugal axons. Available evidence points to early and substantial degeneration of the BFCN in AD and diffuse Lewy body disease. In AD, the major neurodegenerative correlate is accumulation of phosphotau in neurofibrillary tangles. However, these neurons are less vulnerable to the tauopathy of FTLD. An intriguing finding is that the intracellular tau of AD causes destruction of the BFCN, whereas that of FTLD does not. This observation has profound implications for exploring the impact of different species of tauopathy on neuronal survival. The proteinopathy of FTLD-TDP shows virtually no abnormal inclusions within the BFCN. Thus, the BFCN are highly vulnerable to the neurodegenerative effects of tauopathy in AD, resilient to the neurodegenerative effect of tauopathy in FTLD and apparently resistant to the emergence of proteinopathy in FTLD-TDP and perhaps also in Pick's disease. Investigations are beginning to shed light on the potential mechanisms of this differential vulnerability and their implications for therapeutic intervention.

Discovery of a Novel Acetylcholinesterase Inhibitor by Fragment-Based Design and Virtual Screening

Despite extensive and intensive research efforts in recent decades, there is still no effective treatment for neurodegenerative diseases. On this background, the use of drugs inhibiting the enzyme acetylcholinesterase (AChE) remains an eternal evergreen in the symptomatic treatment of mild to moderate cognitive impairments. Even more, the cholinergic hypothesis, somewhat forgotten in recent years due to the shift in focus on amyloid cascade, is back to life, and the search for new, more effective AChE inhibitors continues. We generated a fragment-based library containing aromatic moieties and linkers originating from a set of novel AChE inhibitors. We used this library to design 1220 galantamine (GAL) derivatives following the model GAL (binding core) - linker (L) - aromatic fragment (Ar). The newly designed compounds were screened virtually for blood–brain barrier (BBB) permeability and binding to AChE. Among the top 10 best-scored compounds, a representative lead molecule was selected and tested for anti-AChE activity and neurotoxicity. It was found that the selected compound was a powerful non-toxic AChE inhibitor, 68 times more active than GAL, and could serve as a lead molecule for further optimization and development.

Paucity of Entorhinal Cortex Pathology of the Alzheimer's Type in SuperAgers with Superior Memory Performance

Advancing age is typically associated with declining memory capacity and increased risk of Alzheimer's disease (AD). Markers of AD such as amyloid plaques (AP) and neurofibrillary tangles (NFTs) are commonly found in the brains of cognitively average elderly but in more limited distribution than in those at the mild cognitive impairment and dementia stages of AD. Cognitive SuperAgers are individuals over age 80 who show superior memory capacity, at a level consistent with individuals 20-30 years their junior. Using a stereological approach, the current study quantitated the presence of AD markers in the memory-associated entorhinal cortex (ERC) of seven SuperAgers compared with six age-matched cognitively average normal control individuals. Amyloid plaques and NFTs were visualized using Thioflavin-S histofluorescence, 6E10, and PHF-1 immunohistochemistry. Unbiased stereological analysis revealed significantly more NFTs in ERC in cognitively average normal controls compared with SuperAgers (P < 0.05) by a difference of ~3-fold. There were no significant differences in plaque density. To highlight relative magnitude, cases with typical amnestic dementia of AD showed nearly 100 times more entorhinal NFTs than SuperAgers. The results suggest that resistance to age-related neurofibrillary degeneration in the ERC may be one factor contributing to preserved memory in SuperAgers.

Endogenous Acetylcholine and Its Modulation of Cortical Microcircuits to Enhance Cognition

Acetylcholine regulates the cerebral cortex to sharpen sensory perception and enhance attentional focus. The cellular and circuit mechanisms of this cholinergic modulation are under active investigation in sensory and prefrontal cortex, but the universality of these mechanisms across the cerebral cortex is not clear. Anatomical maps suggest that the sensory and prefrontal cortices receive distinct cholinergic projections and have subtle differences in the expression of cholinergic receptors and the metabolic enzyme acetylcholinesterase. First, we briefly review this anatomical literature and the recent progress in the field. Next, we discuss in detail the electrophysiological effects of cholinergic receptor subtypes and the cell and circuit consequences of their stimulation by endogenous acetylcholine as established by recent optogenetic work. Finally, we explore the behavioral ramifications of in vivo manipulations of endogenous acetylcholine. We find broader similarities than we expected between the cholinergic regulation of sensory and prefrontal cortex, but there are some differences and some gaps in knowledge. In visual, auditory, and somatosensory cortex, the cell and circuit mechanisms of cholinergic sharpening of sensory perception have been probed in vivo with calcium imaging and optogenetic experiments to simultaneously test mechanism and measure the consequences of manipulation. By contrast, ascertaining the links between attentional performance and cholinergic modulation of specific prefrontal microcircuits is more complicated due to the nature of the required tasks. However, ex vivo optogenetic manipulations point to differences in the cholinergic modulation of sensory and prefrontal cortex. Understanding how and where acetylcholine acts within the cerebral cortex to shape cognition is essential to pinpoint novel treatment targets for the perceptual and attention deficits found in multiple psychiatric and neurological disorders.

Understanding brain resilience in superagers: a systematic review

PURPOSE

Superagers are older adults presenting excellent memory performance that may reflect resilience to the conventional pathways of aging. Our contribution aims to shape the evidence body of the known distinctive biomarkers of superagers and their connections with the Brain and Cognitive Reserve and Brain Maintenance concepts.

METHODS

We performed a systematic literature search in PubMed and ScienceDirect with no limit on publication date for studies that evaluated potential biomarkers in superagers classified by validated neuropsychological tests. Methodological quality was assessed using the QUADAS-2 tool.

RESULTS

Twenty-one studies were included, the majority in neuroimaging, followed by histological, genetic, cognition, and a single one on blood plasma analysis. Superagers exhibited specific regions of cortical preservation, rather than global cortical maintenance, standing out the anterior cingulate and hippocampus regions. Both superagers and controls showed similar levels of amyloid deposition. Moreover, the functional oscillation patterns in superagers resembled those described in young adults. Most of the quality assessment for the included studies showed medium risks of bias.

CONCLUSION

This systematic review supports selective cortical preservation in superagers, comprehending regions of the default mode, and salience networks, overlapped by stronger functional connectivity. In this context, the anterior cingulate cortex is highlighted as an imaging and histologic signature of these subjects. Besides, the biomarkers included pointed out that the Brain and Cognitive Reserve and Brain Maintenance concepts are independent and complementary in the superagers' setting.

Improving Anti-Neurodegenerative Benefits of Acetylcholinesterase Inhibitors in Alzheimer's Disease: Are Irreversible Inhibitors the Future?

Decades of research have produced no effective method to prevent, delay the onset, or slow the progression of Alzheimer's disease (AD). In contrast to these failures, acetylcholinesterase (AChE, EC 3.1.1.7) inhibitors slow the clinical progression of the disease and randomized, placebo-controlled trials in prodromal and mild to moderate AD patients have shown AChE inhibitor anti-neurodegenerative benefits in the cortex, hippocampus, and basal forebrain. CNS neurodegeneration and atrophy are now recognized as biomarkers of AD according to the National Institute on Aging-Alzheimer's Association (NIA-AA) criteria and recent evidence shows that these markers are among the earliest signs of prodromal AD, before the appearance of amyloid. The current AChE inhibitors (donepezil, rivastigmine, and galantamine) have short-acting mechanisms of action that result in dose-limiting toxicity and inadequate efficacy. Irreversible AChE inhibitors, with a long-acting mechanism of action, are inherently CNS selective and can more than double CNS AChE inhibition possible with short-acting inhibitors. Irreversible AChE inhibitors open the door to high-level CNS AChE inhibition and improved anti-neurodegenerative benefits that may be an important part of future treatments to more effectively prevent, delay the onset, or slow the progression of AD.

Walnut Oil Prevents Scopolamine-Induced Memory Dysfunction in a Mouse Model

For thousands of years, it has been widely believed that walnut is a kind of nut that has benefits for the human body. Walnut oil, accounting for about 70% of walnut, mainly consists of polyunsaturated fatty acids. To investigate the effect of walnut oil on memory impairment in mice, scopolamine (3 mg/kg body weight/d) was used to establish the animal model during Morris Water Maze (MWM) tests. Walnut oil was administrated orally at 10 mL/kg body weight/d for 8 consecutive weeks. The results showed that walnut oil treatment ameliorated the behavior of the memory-impaired mice in the MWM test. Additionally, walnut oil obviously inhibited acetylcholinesterase activity (1.26 ± 0.12 U/mg prot) (p = 0.013) and increased choline acetyltransferase activity (129.75 ± 6.76 U/mg tissue wet weight) in the brains of scopolamine-treated mice (p = 0.024), suggesting that walnut oil could prevent cholinergic function damage in mice brains. Furthermore, walnut oil remarkably prevented the decrease in total superoxide dismutase activity (93.30 ± 5.50 U/mg prot) (p = 0.006) and glutathione content (110.45 ± 17.70 mg/g prot) (p = 0.047) and the increase of malondialdehyde content (13.79 ± 0.96 nmol/mg prot) (p = 0.001) in the brain of scopolamine-treated mice, indicating that walnut oil could inhibit oxidative stress in the brain of mice. Furthermore, walnut oil prevented histological changes of neurons in hippocampal CA1 and CA3 regions induced by scopolamine. These findings indicate that walnut oil could prevent memory impairment in mice, which might be a potential way for the prevention of memory dysfunctions.

Cholinergic and inflammatory phenotypes in transgenic tau mouse models of Alzheimer's disease and frontotemporal lobar degeneration

An early and sizeable loss of basal forebrain cholinergic neurons is a well-characterized feature associated with measurable deficits in spatial learning and cognitive impairment in patients with Alzheimer’s disease. In addition, pro-inflammatory glial cells such as astrocytes and microglia may play a key role in the neurodegenerative cascade of Alzheimer’s disease and tauopathies. We recently presented two mouse models: Line 1, expressing the truncated tau fragment identified as the core of the Alzheimer’s paired helical filament, and Line 66, expressing full-length human tau carrying a double mutation (P301S and G335D). Line 1 mice have a pathology that is akin to Alzheimer’s, whilst Line 66 resembles frontotemporal lobar degeneration. However, their cholinergic and inflammatory phenotypes remain elusive. We performed histological evaluation of choline acetyltransferase, acetylcholinesterase, p75 neurotrophin receptor, microglial ionized calcium binding adaptor molecule 1 and astrocytic glial fibrillary acidic protein in the basal forebrain, hippocampus and cortex of these models. A significant lowering of choline acetyltransferase-positive neurons and p75-positive neurons in the basal forebrain of Line 1 at 3, 6 and 9 months was observed in two independent studies, alongside a significant decrease in acetylcholinesterase staining in the cortex and hippocampus. The reductions in choline acetyltransferase positivity varied between 30% and 50% at an age when Line 1 mice show spatial learning impairments. Furthermore, an increase in microglial ionized calcium binding adaptor molecule 1 staining was observed in the basal forebrain, hippocampus and entorhinal cortex of Line 1 at 6 months. Line 66 mice displayed an intact cholinergic basal forebrain, and no difference in p75-positive neurons at 3 or 9 months. In addition, Line 66 exhibited significant microglial ionized calcium binding adaptor molecule 1 increase in the basal forebrain and hippocampus, suggesting a prominent neuroinflammatory profile. Increased concentrations of microglial interleukin-1β and astrocytic complement 3 were also seen in the hippocampus of both Line 1 and Line 66. The cholinergic deficit in Line 1 mice confirms the Alzheimer’s disease-like phenotype in Line 1 mice, whilst Line 66 revealed no measurable change in total cholinergic expression, a phenotypic trait of frontotemporal lobar degeneration. These two transgenic lines are therefore suitable for discriminating mechanistic underpinnings between the Alzheimer’s and frontotemporal lobar degeneration-like phenotypes of these mice.

Magnetic resonance imaging of brain cell water

In the central nervous system of vertebrates, cell bodies of neurons are often assembled as nuclei or cellular layers that play specific roles as functional units. The purpose of this work was to selectively highlight such cell assemblies by magnetic resonance imaging using signals from water protons that are associated with intracellular paramagnetic ions, while saturating lipid-associated water protons as well as extracellular free water protons. Given the significant correlation between image signal intensity and water proton density, the high signal intensities observed for such cell assemblies must be attributed to their abundant paramagnetic-ion-associated water protons. In the hippocampal formation, the technique visualized cell assemblies that were so far not depicted in human in vivo. In the brainstem, the technique delineated noradrenergic neuron groups such as the locus coeruleus in human and mice in vivo. Their reduced magnetization-transfer ratios together with their prolonged relaxation times compared to other gray matter indicate that the source of their high signal intensity is not the presence of T₁-shortening molecules, e.g., neuromelanin, but their high water content. Given the general absence of neuromelanin in noradrenergic neurons of rodents, their high signal intensity in mice in vivo further supports this view.

Early growth response-1 regulates acetylcholinesterase and its relation with the course of Alzheimer's disease

Our previous studies showed that the transcription factor early growth response-1 (EGR1) may play a role in keeping the brain cholinergic function intact in the preclinical stages of Alzheimer's disease (AD). In order to elucidate the mechanisms involved, we first performed data mining on our previous microarray study on postmortem human prefrontal cortex (PFC) for the changes in the expression of EGR1 and acetylcholinesterase (AChE) and the relationship between them during the course of AD. The study contained 49 patients, ranging from non-demented controls (Braak stage 0) to late AD patients (Braak stage VI). We found EGR1-mRNA was high in early AD and decreased in late AD stages, while AChE-mRNA was stable in preclinical AD and slightly decreased in late AD stages. A significant positive correlation was found between the mRNA levels of these two molecules. In addition, we studied the relationship between EGR1 and AChE mRNA levels in the frontal cortex of 3-12-months old triple-transgenic AD (3xTg-AD) mice. EGR1- and AChE-mRNA were lower in 3xTg-AD mice compared with wild-type (WT) mice. A significant positive correlation between these two molecules was present in the entire group and in each age group of either WT or 3xTg-AD mice. Subsequently, AChE expression was determined following up- or down-regulating EGR1 in cell lines and the EGR1 levels were found to regulate AChE at both the mRNA and protein levels. Dual-luciferase assay and electrophoretic mobility shift assay in the EGR1-overexpressing cells were performed to determine the functionally effective binding sites of the EGR1 on the AChE gene promoter. We conclude that the EGR1 can upregulate AChE expression by a direct effect on its gene promoter, which may contribute significantly to the changes in cholinergic function in the course of AD. The 3xTg-AD mouse model only reflects later stage AD.

7-Chloro-4-(Phenylselanyl) Quinoline with Memory Enhancer Action in Aging Rats: Modulation of Neuroplasticity, Acetylcholinesterase Activity, and Cholesterol Levels

This study investigated the effect of 7-chloro-4-(phenylselanyl) quinoline (4-PSQ) to restore the cognitive impairment caused by aging in male Wistar rats. Moreover, modulation of neuroplasticity markers, acetylcholinesterase (AChE) activity, and cholesterol levels was performed. Aged rats were intragastrically treated with 4-PSQ (5 mg/kg) for 7 days. Animals were tested in behavioral tasks, and then plasma (to determine cholesterol levels), hippocampus, and cerebral cortex (to determine neural cell adhesion molecule (NCAM) and polysialyltransferase (PST) levels, and AChE activity) were removed. Our findings demonstrated that treatment of aged rats with 4-PSQ restored short-term and long-term memories in the object recognition tests. 4-PSQ treatment did not restore exploratory activity (rearings) but partially restored locomotor activity (crossings) reduced by aging in the open-field test. Moreover, the compound restored the reduction in the NCAM and PST levels, and AChE activity in cerebral structures, as well as the increase in the plasma cholesterol levels, caused by aging in rats. In conclusion, 4-PSQ restored cognitive impairment caused by aging in rats by modulating synaptic plasticity, cholinergic system, and cholesterol levels.

Neuroprotective Effects of the Multitarget Agent AVCRI104P3 in Brain of Middle-Aged Mice

Molecular factors involved in neuroprotection are key in the design of novel multitarget drugs in aging and neurodegeneration. AVCRI104P3 is a huprine derivative that exhibits potent inhibitory effects on human AChE, BuChE, and BACE-1 activities, as well as on AChE-induced and self-induced Aβ aggregation. More recently, cognitive protection and anxiolytic-like effects have also been reported in mice treated with this compound. Now, we have assessed the ability of AVCRI104P3 (0.43 mg/kg, 21 days) to modulate the levels of some proteins involved in the anti-apoptotic/apoptotic processes (pAkt1, Bcl2, pGSK3β, p25/p35), inflammation (GFAP and Iba1) and neurogenesis in C57BL/6 mice. The effects of AVCRI104P3 on AChE-R/AChE-S isoforms have been also determined. We have observed that chronic treatment of C57BL/6 male mice with AVCRI104P3 results in neuroprotective effects, increasing significantly the levels of pAkt1 and pGSK3β in the hippocampus and Bcl2 in both hippocampus and cortex, but slightly decreasing synaptophysin levels. Astrogliosis and neurogenic markers GFAP and DCX remained unchanged after AVCRI104P3 treatment, whereas microgliosis was found to be significantly decreased pointing out the involvement of this compound in inflammatory processes. These results suggest that the neuroprotective mechanisms that are behind the cognitive and anxiolytic effects of AVCRI104P3 could be partly related to the potentiation of some anti-apoptotic and anti-inflammatory proteins and support the potential of AVCRI104P3 for the treatment of brain dysfunction associated with aging and/or dementia.

Operationalized definition of older adults with high cognitive performance

Recently, there has been an increasing number of studies on exceptional cognitive aging. Herein, we aim to objectively provide the operationalized characterization of older adults with unusually high memory ability. Some authors have defined them as "SuperAgers", individuals aged 80 years or older with memory ability similar or superior to middle-aged subjects. On the other hand, the terminology "high-performing older adults" (HPOA) seems to appropriately conceptualize these individuals without exaggeration. A threshold for age is not a reliable criterion, but may be defined as 75 and 80 years of age for developing and developed countries, respectively. We propose that HPOA may exhibit episodic memory test scores equal to or greater than those of individuals aged 50-60 years, according to the validated tables for the respective country. This group must also have global cognition scores within expected average values for age and education. Executive functioning may play a central role in the exceptional memory performance of this group. Further studies are essential to confirm existing findings and may provide important evidence for cognitive aging theory and the neurobiology of dementia.

Acetylcholine Neuromodulation in Normal and Abnormal Learning and Memory: Vigilance Control in Waking, Sleep, Autism, Amnesia and Alzheimer's Disease

Adaptive Resonance Theory, or ART, is a neural model that explains how normal and abnormal brains may learn to categorize and recognize objects and events in a changing world, and how these learned categories may be remembered for a long time. This article uses ART to propose and unify the explanation of diverse data about normal and abnormal modulation of learning and memory by acetylcholine (ACh). In ART, vigilance control determines whether learned categories will be general and abstract, or specific and concrete. ART models how vigilance may be regulated by ACh release in layer 5 neocortical cells by influencing after-hyperpolarization (AHP) currents. This phasic ACh release is mediated by cells in the nucleus basalis (NB) of Meynert that are activated by unexpected events. The article additionally discusses data about ACh-mediated tonic control of vigilance. ART proposes that there are often dynamic breakdowns of tonic control in mental disorders such as autism, where vigilance remains high, and medial temporal amnesia, where vigilance remains low. Tonic control also occurs during sleep-wake cycles. Properties of Up and Down states during slow wave sleep arise in ACh-modulated laminar cortical ART circuits that carry out processes in awake individuals of contrast normalization, attentional modulation, decision-making, activity-dependent habituation, and mismatch-mediated reset. These slow wave sleep circuits interact with circuits that control circadian rhythms and memory consolidation. Tonic control properties also clarify how Alzheimer's disease symptoms follow from a massive structural degeneration that includes undermining vigilance control by ACh in cortical layers 3 and 5. Sleep disruptions before and during Alzheimer's disease, and how they contribute to a vicious cycle of plaque formation in layers 3 and 5, are also clarified from this perspective.