Serotonergic system, cognition, and BPSD in Alzheimer's disease

Beyond memory impairment: the complex phenotypic landscape of Alzheimer's disease

Neuropsychiatric symptoms (NPSs) in Alzheimer's disease (AD) constitute multifaceted behavioral manifestations that reflect processes of emotional regulation, thinking, and social behavior. They are as prevalent in AD as cognitive impairment and develop independently during the progression of neurodegeneration. As studying NPSs in AD is clinically challenging, most AD research to date has focused on cognitive decline. In this opinion article we summarize emerging literature on the prevalence, time course, and the underlying genetic, molecular, and pathological mechanisms related to NPSs in AD. Overall, we propose that NPSs constitute a cluster of core symptoms in AD, and understanding their neurobiology can lead to a more holistic approach to AD research, paving the way for more accurate diagnostic tests and personalized treatments embracing the goals of precision medicine.

Serotonergic dysfunction may mediate the relationship between alcohol consumption and Alzheimer's disease

The impact of Alzheimer's disease (AD) and its related dementias is rapidly expanding, and its mitigation remains an urgent social and technical challenge. To date there are no effective treatments or interventions for AD, but recent studies suggest that alcohol consumption is correlated with the risk of developing dementia. In this review, we synthesize data from preclinical, clinical, and epidemiological models to evaluate the combined role of alcohol consumption and serotonergic dysfunction in AD, underscoring the need for further research on this topic. We first discuss the limitations inherent to current data-collection methods, and how neuropsychiatric symptoms common among AD, alcohol use disorder, and serotonergic dysfunction may mask their co-occurrence. We additionally describe how excess alcohol consumption may accelerate the development of AD via direct effects on serotonergic function, and we explore the roles of neuroinflammation and proteostasis in mediating the relationship between serotonin, alcohol consumption, and AD. Lastly, we argue for a shift in current research to disentangle the pathogenic effects of alcohol on early-affected brainstem structures in AD.

Innovative pathological network-based multitarget approaches for Alzheimer's disease treatment

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease and is a major health threat globally. Its prevalence is forecasted to exponentially increase during the next 30 years due to the global aging population. Currently, approved drugs are merely symptomatic, being ineffective in delaying or blocking the relentless disease advance. Intensive AD research describes this disease as a highly complex multifactorial disease. Disclosure of novel pathological pathways and their interconnections has had a major impact on medicinal chemistry drug development for AD over the last two decades. The complex network of pathological events involved in the onset of the disease has prompted the development of multitarget drugs. These chemical entities combine pharmacological activities toward two or more drug targets of interest. These multitarget-directed ligands are proposed to modify different nodes in the pathological network aiming to delay or even stop disease progression. Here, we review the multitarget drug development strategy for AD during the last decade.

Alignments between cortical neurochemical systems, proteinopathy and neurophysiological alterations along the Alzheimer's disease continuum

Two neuropathological hallmarks of Alzheimer's disease (AD) are the accumulation of amyloid-β (Aβ) proteins and alterations in cortical neurophysiological signaling. Despite parallel research indicating disruption of multiple neurotransmitter systems in AD, it has been unclear whether these two phenomena are related to the neurochemical organization of the cortex. We leveraged task-free magnetoencephalography and positron emission tomography, with a cortical atlas of 19 neurotransmitters to study the alignment and interactions between alterations of neurophysiological signaling, Aβ deposition, and the neurochemical gradients of the human cortex. In patients with amnestic mild cognitive impairment (N = 18) and probable AD (N = 20), we found that changes in rhythmic, but not arrhythmic, cortical neurophysiological signaling relative to healthy controls (N = 20) are topographically aligned with cholinergic, serotonergic, and dopaminergic neurochemical systems. These neuro-physio-chemical alignments are related to the severity of cognitive and behavioral impairments. We also found that cortical Aβ plaques are preferentially deposited along neurochemical boundaries, and mediate how beta-band rhythmic cortical activity maps align with muscarinic acetylcholine receptors. Finally, we show in an independent dataset that many of these alignments manifest in the asymptomatic stages of cortical Aβ accumulation (N = 33; N = 71 healthy controls), particularly the Aβ-neurochemical alignments (57.1%) and neuro-physio-chemical alignments in the alpha frequency band (62.5%). Overall, the present study demonstrates that the expression of pathology in pre-clinical and clinical AD aligns topographically with the cortical distribution of chemical neuromodulator systems, scaling with clinical severity and with implications for potential pharmacotherapeutic pathways.

Serotonin deficiency from constitutive SKN-1 activation drives pathogen apathy

When an organism encounters a pathogen, the host innate immune system activates to defend against pathogen colonization and toxic xenobiotics produced. C. elegans employ multiple defense systems to ensure survival when exposed to Pseudomonas aeruginosa including activation of the cytoprotective transcription factor SKN-1/NRF2. Although wildtype C. elegans quickly learn to avoid pathogens, here we describe a peculiar apathy-like behavior towards PA14 in animals with constitutive activation of SKN-1, whereby animals choose not to leave and continue to feed on the pathogen even when a non-pathogenic and healthspan-promoting food option is available. Although lacking the urgency to escape the infectious environment, animals with constitutive SKN-1 activity are not oblivious to the presence of the pathogen and display the typical pathogen-induced intestinal distension and eventual demise. SKN-1 activation, specifically in neurons and intestinal tissues, orchestrates a unique transcriptional program which leads to defects in serotonin signaling that is required from both neurons and non-neuronal tissues. Serotonin depletion from SKN-1 activation limits pathogen defense capacity, drives the pathogen-associated apathy behaviors and induces a synthetic sensitivity to selective serotonin reuptake inhibitors. Taken together, our work reveals new insights into how animals perceive environmental pathogens and subsequently alter behavior and cellular programs to promote survival.

KEY POINTS

Identify an apathy-like behavioral response for pathogens resulting from the constitutive activation of the cytoprotective transcription factor SKN-1.Uncover the obligate role for serotonin synthesis in both neuronal and non-neuronal cells for the apathy-like state and ability of serotonin treatment to restore normal behaviors.Characterize the timing and tissue specificity of SKN-1 nuclear localization in neurons and intestinal cells in response to pathogen exposure.Define the unique and context-specific transcriptional signatures of animals with constitutive SKN-1 activation when exposed to pathogenic environments.Reveal necessity for both neuronal and non-neuronal serotonin signaling in host survival from pathogen infection.

Distinguishing features of depression in dementia from primary psychiatric disease

Depression is a common and devastating neuropsychiatric symptom in the elderly and in patients with dementia. In particular, nearly 80% of patients with Alzheimer's Disease dementia experience depression during disease development and progression. However, it is unknown whether the depression in patients with dementia shares the same molecular mechanisms as depression presenting as primary psychiatric disease or occurs and persists through alternative mechanisms. In this review, we discuss how the clinical presentation and treatment differ between depression in dementia and as a primary psychiatric disease, with a focus on major depressive disorder. Then, we hypothesize several molecular mechanisms that may be unique to depression in dementia such as neuropathological changes, inflammation, and vascular events. Finally, we discuss existing issues and future directions for investigation and treatment of depression in dementia.

Exercise to prevent the negative effects of sleep deprivation: A systematic review and meta-analysis

Ample sleep is an important basis for maintaining health, however with the pace of life accelerating in modern society, more people are using sacrificial sleep to cope with these social changes. Sleep deprivation can have negative effects on cognitive performance and psychosomatic health. It is well known that exercise, as a beneficial intervention strategy for human health, has been increasingly used in the clinic. But it's not clear if it can prevent the negative effects of sleep deprivation. In this meta-analysis, we reviewed 23 articles from PubMed and Web of Science to investigate whether moderate physical exercise can prevent the negative effects of sleep deprivation in rodents. Our findings suggest that exercise can prevent sleep deprivation-induced cognitive impairment and anxiety-like behaviors through multiple pathways. We also discuss possible molecular mechanisms involved in this protective effect, highlighting the potential of exercise as a preventive or therapeutic strategy for sleep deprivation-induced negative effects.

Anxiety and Alzheimer's disease pathogenesis: focus on 5-HT and CRF systems in 3xTg-AD and TgF344-AD animal models

Dementia remains one of the leading causes of morbidity and mortality in older adults. Alzheimer's disease (AD) is the most common type of dementia, affecting over 55 million people worldwide. AD is characterized by distinct neurobiological changes, including amyloid-beta protein deposits and tau neurofibrillary tangles, which cause cognitive decline and subsequent behavioral changes, such as distress, insomnia, depression, and anxiety. Recent literature suggests a strong connection between stress systems and AD progression. This presents a promising direction for future AD research. In this review, two systems involved in regulating stress and AD pathogenesis will be highlighted: serotonin (5-HT) and corticotropin releasing factor (CRF). Throughout the review, we summarize critical findings in the field while discussing common limitations with two animal models (3xTg-AD and TgF344-AD), novel pharmacotherapies, and potential early-intervention treatment options. We conclude by highlighting promising future pharmacotherapies and translational animal models of AD and anxiety.

Mitochondrial Interaction with Serotonin in Neurobiology and Its Implication in Alzheimer's Disease

Alzheimer's disease (AD) is a lethal neurodegenerative disorder characterized by severe brain pathologies and progressive cognitive decline. While the exact cause of this disease remains unknown, emerging evidence suggests that dysregulation of neurotransmitters contributes to the development of AD pathology and symptoms. Serotonin, a critical neurotransmitter in the brain, plays a pivotal role in regulating various brain processes and is implicated in neurological and psychiatric disorders, including AD. Recent studies have shed light on the interplay between mitochondrial function and serotonin regulation in brain physiology. In AD, there is a deficiency of serotonin, along with impairments in mitochondrial function, particularly in serotoninergic neurons. Additionally, altered activity of mitochondrial enzymes, such as monoamine oxidase, may contribute to serotonin dysregulation in AD. Understanding the intricate relationship between mitochondria and serotonin provides valuable insights into the underlying mechanisms of AD and identifies potential therapeutic targets to restore serotonin homeostasis and alleviate AD symptoms. This review summarizes the recent advancements in unraveling the connection between brain mitochondria and serotonin, emphasizing their significance in AD pathogenesis and underscoring the importance of further research in this area. Elucidating the role of mitochondria in serotonin dysfunction will promote the development of therapeutic strategies for the treatment and prevention of this neurodegenerative disorder.

Emphasizing the Crosstalk Between Inflammatory and Neural Signaling in Post-traumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a chronic incapacitating condition with recurrent experience of trauma-related memories, negative mood, altered cognition, and hypervigilance. Agglomeration of preclinical and clinical evidence in recent years specified that alterations in neural networks favor certain characteristics of PTSD. Besides the disruption of hypothalamus-pituitary-axis (HPA) axis, intensified immune status with elevated pro-inflammatory cytokines and arachidonic metabolites of COX-2 such as PGE2 creates a putative scenario in worsening the neurobehavioral facet of PTSD. This review aims to link the Diagnostic and Statistical Manual of mental disorders (DSM-V) symptomology to major neural mechanisms that are supposed to underpin the transition from acute stress reactions to the development of PTSD. Also, to demonstrate how these intertwined processes can be applied to probable early intervention strategies followed by a description of the evidence supporting the proposed mechanisms. Hence in this review, several neural network mechanisms were postulated concerning the HPA axis, COX-2, PGE2, NLRP3, and sirtuins to unravel possible complex neuroinflammatory mechanisms that are obscured in PTSD condition.

The Importance of Person-Centered Approaches to Managing Behavioral and Psychological Symptoms of Dementia: A Case Report

Behavioral and psychological symptoms of dementia (BPSD) are common and associated with increased morbidity and mortality in dementia. In this report, we describe a patient with severe BPSD who was effectively managed with a variety of non-pharmacologic strategies. A 70-year-old Navy veteran and retired commercial flooring business owner with a history of dementia was admitted to the hospital with aggressive behavior. He was no longer manageable by his family. He required intermittent use of restraints and multiple antipsychotics during hospitalization. He spent much of his time crawling on the floor, "working" on floor tiles, which was often difficult for staff to safely accommodate. However, with time, interprofessional staff identified signs of distress and developed strategies to safely engage the patient's current perception of his situation. This case highlights how BPSD may be driven by a person's identities and roles from earlier stages of life. Approaching and managing these symptoms flexibly can enhance dementia care.

A Feasibility Evaluation of the Need-Centered Watch-Assess-Need Intervention-Think Education and Training Program for Behavioral and Psychological Symptoms of Dementia

BACKGROUND

Despite the high prevalence of dementia among residents living in long-term care facilities in Taiwan, most care providers in these facilities have not received adequate training to deal with the behavioral and psychological symptoms of dementia (BPSD). An original care and management model for BPSD has been developed, and model-based recommendations for an education and training program have been made. However, empirical testing has not yet been conducted to determine the efficacy of this program.

PURPOSE

This study was designed to evaluate the feasibility of using the Watch-Assess-Need intervention-Think (WANT) education and training program for BPSD in long-term care settings.

METHODS

A mixed-method design was used. Twenty care providers and 20 corresponding care receivers (residents with dementia) from a nursing home in southern Taiwan were enrolled. Data were collected using a variety of measurement tools, including the Cohen-Mansfield Agitation Inventory, Cornell Scale for Depression in Dementia, Attitude towards Dementia Care Scale, and Dementia Behavior Disturbance Self-efficacy Scale. Qualitative data, including care-provider perspectives on the efficacy of the WANT education and training program, were also collected. Repeated measures were conducted on the results of quantitative data analysis, whereas content analysis was performed on the results of qualitative data analysis.

RESULTS

Findings indicate that the program relieves agitated behavior (p = .01), alleviates depression in those with dementia (p < .001), and enhances care-provider attitudes toward dementia care (p = .01). However, no significant improvement was found in self-efficacy among the care providers (p = .11). In terms of qualitative outcomes, care providers indicated they perceived improved self-efficacy in managing BPSD, improved ability to view problems from a more need-centered perspective, improved attitudes toward dementia and patients' BPSD, and decreased care burden and stress.

CONCLUSIONS/IMPLICATIONS FOR PRACTICE

The study found the WANT education and training program to be feasible in clinical practice. Because of this program's simple and easy-to-remember characteristics, it is recommended that it be vigorously promoted to care providers in both long-term institutional and home care settings to help them effectively address the BPSD.

Alzheimer’s Disease and Alzheimer’s Disease-Related Dementias in African Americans: Focus on Caregivers

Alzheimer’s disease (AD) and Alzheimer’s Disease-Related Dementias (ADRD) are chronic illnesses that are highly prevalent in African Americans (AA). AD and ADRD are caused by multiple factors, such as genetic mutations, modifiable and non-modifiable risk factors, and lifestyle. Histopathological, morphological, and cellular studies revealed how multiple cellular changes are implicated in AD and ADRD, including synaptic damage, inflammatory responses, hormonal imbalance, mitochondrial abnormalities, and neuronal loss, in addition to the accumulation of amyloid beta and phosphorylated tau in the brain. The contributions of race, ethnicity, location and socioeconomic status all have a significant impact on the care and support services available to dementia patients. Furthermore, disparities in health care are entangled with social, economic, and environmental variables that perpetuate disadvantages among different groups, particularly African Americans. As such, it remains important to understand how various racial and ethnic groups perceive, access, and experience health care. Considering that the mounting data shows AA may be more susceptible to AD than white people, the demographic transition creates significant hurdles in providing adequate care from family caregivers. Furthermore, there is growing recognition that AD and ADRD pose a significant stress on AA caregivers compared to white people. In this review, we examine the current literature on racial disparities in AD and ADRD, particularly concerning AA caregivers.

Neuropsychiatric Symptoms of Alzheimer's Disease: An Anatomic-Genetic Framework for Treatment Development

BACKGROUND

Despite the burden on patients and caregivers, there are no approved therapies for the neuropsychiatric symptoms of Alzheimer's disease (NPS-AD). This is likely due to an incomplete understanding of the underlying mechanisms.

OBJECTIVE

To review the neurobiological mechanisms of NPS-AD, including depression, psychosis, and agitation.

METHODS

Understanding that genetic encoding gives rise to the function of neural circuits specific to behavior, we review the genetics and neuroimaging literature to better understand the biological underpinnings of depression, psychosis, and agitation.

RESULTS

We found that mechanisms involving monoaminergic biosynthesis and function are likely key elements of NPS-AD and while current treatment approaches are in line with this, the lack of effectiveness may be due to contributions from additional mechanisms including neurodegenerative, vascular, inflammatory, and immunologic pathways.

CONCLUSION

Within an anatomic-genetic framework, development of novel effective biological targets may engage targets within these pathways but will require a better understanding of the heterogeneity in NPS-AD.

Potential beneficial effects of masupirdine (SUVN-502) on agitation/aggression and psychosis in patients with moderate Alzheimer's disease: Exploratory post hoc analyses

OBJECTIVES

The effects of masupirdine on the neuropsychiatric symptoms were explored.

METHODS

Masupirdine (SUVN-502) was evaluated for its effects on cognition in patients with moderate AD. The prespecified primary outcome showed no drug-placebo difference. Post hoc analyses of domains of the 12-item neuropsychiatric inventory scale were carried out.

RESULTS

In a subgroup of patients (placebo, n = 57; masupirdine 50 mg, n = 53; masupirdine 100 mg, n = 48) with baseline agitation/aggression symptoms ≥1, a statistically significant reduction in agitation/aggression scores was observed in masupirdine 50 mg (95% confidence interval (CI), -1.9 to -0.5, p < 0.001) and masupirdine 100 mg (95% CI, -1.7 to -0.3, p = 0.007) treated arms at Week 13 in comparison to placebo and the effect was sustained for trial duration of 26 weeks in the masupirdine 50 mg treatment arm (95% CI, -2.3 to -0.8, p < 0.001). Similar observations were noted in the subgroup of patients (placebo, n = 29; masupirdine 50 mg, n = 30; masupirdine 100 mg, n = 21) with baseline agitation/aggression symptoms ≥3. In the subgroup of patients (placebo, n = 28; masupirdine 50 mg, n = 28; masupirdine 100 mg, n = 28) who had baseline psychosis symptoms and/or symptom emergence, a significant reduction in psychosis scores was observed in the masupirdine 50 mg (Week 4: 95% CI, -2.8 to -1.4, p < 0.001; Week 13: 95% CI, -3.3 to -1.3, p < 0.001) and masupirdine 100 mg (Week 4: 95% CI, -1.4 to 0, p = 0.046; Week 13: 95% CI, -1.9 to 0.1, p = 0.073) treatment arms in comparison to placebo.

CONCLUSION

Further research is warranted to explore the potential beneficial effects of masupirdine on NPS.

Genetically predicted circulating levels of glycine, glutamate, and serotonin in relation to the risks of three major neurodegenerative diseases: A Mendelian randomization analysis

It has been previously postulated that blood neurotransmitters might affect risks of neurodegenerative diseases. Here, a Mendelian Randomization (MR) study was conducted to explore whether genetically predicted concentrations of glycine, glutamate and serotonin were associated with risks of Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). From three genome-wide association studies of European ancestry, single nucleotide polymorphisms strongly associated with glycine, glutamate and serotonin were selected as genetic instrumental variables. Corresponding summary statistics were also obtained from the latest genome-wide association meta-analyses of AD, PD and ALS. The inverse-variance weighted MR and multiple sensitivity analyses were performed to evaluate causal effects of genetically predicted levels of neurotransmitters on risks of neurodegenerative diseases. The statistical significance threshold was set at P < 0.0056 using the Bonferroni-correction, while 0.0056 < P < 0.05 was considered suggestive evidence for a causal association. There was a causal association of elevated blood glutamate levels with higher AD risks. The odds ratio (OR) of AD was 1.311 [95% confidence interval (CI), 1.087-1.580; P = 0.004] per one standard deviation increase in genetically predicted glutamate concentrations. There was suggestive evidence in support of a protective effect of blood serotonin on AD (OR = 0.607; 95% CI, 0.396-0.932; P = 0.022). Genetically predicted glycine levels were not associated with the risk of AD (OR = 1.145; 95% CI, 0.939-1.396; P = 0.180). Besides, MR analyses indicated no causal roles of three blood neurotransmitters in PD or ALS. In conclusion, the MR study provided evidence supporting the association of elevated blood glutamate levels with higher AD risks and the association of increased blood serotonin levels with lower AD risks. Triangulating evidence across further study designs is still warranted to elucidate the role of blood neurotransmitters in risks of neurodegenerative diseases.

Behavioral and psychological symptoms in neurodegenerative dementias: harbinger, follower, or constant collateral?

Neurodegenerative dementias such as the behavioral variant of frontotemporal dementia, Alzheimer’s disease, and Parkinson’s disease dementia are linked to various behavioral and psychological abnormalities. Whether these abnormalities precede, coincide or follow the onset of cognitive symptoms is still controversial in existing literature, with trajectories available so far dependent on types of dementia. The authors aim to review the different kinds of premorbid behavioral symptoms/personality traits associated with an increased risk of developing specific types of neurodegenerative dementia. Neuroticism has been associated with an increased risk of Alzheimer’s disease and late-onset behavioral abnormalities with the behavioral variant of frontotemporal dementia. The presence of obsessive–compulsive spectrum disorders in Parkinson’s disease dementia is also not rare. Analyzing this evidence, we propose “behavioral biomarkers” as neuroticism in Alzheimer’s disease, late-onset behavioral abnormalities in behavioral variant of frontotemporal dementia, and obsessive–compulsive traits in Parkinson’s disease dementia. These noninvasive behavioral biomarkers will be of immense help, particularly in developing countries, and will prevent the need for costlier investigations and aid in therapeutic strategies.

Cryo-EM Structure and Activator Screening of Human Tryptophan Hydroxylase 2

Human tryptophan hydroxylase 2 (TPH2) is the rate-limiting enzyme in the synthesis of serotonin. Its dysfunction has been implicated in various psychiatric disorders such as depression, autism, and bipolar disorder. TPH2 is typically decreased in stability and catalytic activity in patients; thus, screening of molecules capable of binding and stabilizing the structure of TPH2 in activated conformation is desired for drug development in mental disorder treatment. Here, we solved the 3.0 Å cryo-EM structure of the TPH2 tetramer. Then, based on the structure, we conducted allosteric site prediction and small-molecule activator screening to the obtained cavity. ZINC000068568685 was successfully selected as the best candidate with highest binding affinity. To better understand the driving forces and binding stability of the complex, we performed molecular dynamics simulation, which indicates that ZINC000068568685 has great potential to stabilize the folding of the TPH2 tetramer to facilitate its activity. The research might shed light on the development of novel drugs targeting TPH2 for the treatment of psychological disorders.

Black and White individuals differ in dementia prevalence, risk factors, and symptomatic presentation

INTRODUCTION

Although dementia prevalence differs by race, it remains unclear whether cognition and neuropsychiatric symptom severity differ between Black and White individuals with dementia.

METHODS

Using National Alzheimer's Coordinating Center (NACC) data, we evaluated dementia prevalence in non-Hispanic Black and White participants and compared their clinicodemographic characteristics. We examined race differences in cognition, neuropsychiatric symptoms, and functional abilities in participants with dementia using multivariable linear and logistic regression models.

RESULTS

We included 5,700 Black and 31,225 White participants across 39 Alzheimer's Disease Research Centers. Of these, 1,528 (27%) Black and 11,267 (36%) White participants had dementia diagnoses. Despite having lower dementia prevalence, risk factors were more prevalent among Black participants. Black participants with dementia showed greater cognitive deficits, neuropsychiatric symptoms/severity, and functional dependence.

DISCUSSION

Despite lower dementia prevalence, Black participants with dementia had more dementia risk factors, as well as greater cognitive impairment and neuropsychiatric symptom severity than White participants.

Cornuside ameliorates cognitive impairments in scopolamine induced AD mice: Involvement of neurotransmitter and oxidative stress

ETHNOPHARMACOLOGICAL RELEVANCE

Cornus officinalis Sieb. et Zucc., traditional Chinese medicine, has been widely used in the treatment of dementia. Cornel iridoid glycosides of Cornus officinalis is therapeutic to Alzheimer's disease (AD), while its pharmacodynamic material basis is not clear. Cornuside, an iridoid glycoside extracted from of Cornus officinalis Sieb. et Zucc, might be a potential anti-AD candidate.

AIM OF THE STUDY

Cornuside was evaluated for its effect on scopolamine induced AD mice, and its action mechanisms were explored.

MATERIALS AND METHODS

ICR mice were administered with 1 mg/kg scopolamine intraperitoneally to induce amnesia. The therapeutic effect of cornuside of cognitive function was evaluated via series of behavioral tests, including Morris water maze test, step-through test and step-down test. In addition, specific enzyme reaction tests were used to detect the content of acetylcholine (ACh) and malondialdehyde (MDA), as well as the activities of acetylcholinesterase (AChE), butyrylcholinesterase (BuChE), choline acetyltransferase (ChAT), superoxide dismutase (SOD), catalase (CAT), monoamine oxidase (MAO) in the brain. The levels of monoamine neurotransmitters were detected by high performance liquid chromatography-electrochemical detection (HPLC-ECD).

RESULTS

Cornuside ameliorated the spatial memory impairment in Morris water maze test and cognitive disruption in step-through and step-down test. Furthermore, cornuside improved the level of ACh by reducing the activities of AChE and BuChE, and increasing the activity of ChAT in hippocampus. Cornuside also increased the levels of monoamine neurotransmitters by inhibiting MAO activity in hippocampus and cortex. In addition, cornuside attenuated MDA by enhancing the activities of SOD and CAT in hippocampus and cortex.

CONCLUSION

Cornuside improved cognitive dysfunction induced by scopolamine in behavioral tests. The mechanisms of cornuside were further investigated from the aspects of neurotransmitters and oxidative stress. Cornuside could inhibit oxidative stress and neurotransmitter hydrolases, increase ACh and monoamine neurotransmitters, which finally contributed to its therapeutic effect on scopolamine induced amnesia.

Future Directions in Molecular Imaging of Neurodegenerative Disorders

The improvement of existing techniques and the development of new molecular imaging methods are an exciting and rapidly developing field in clinical care and research of neurodegenerative disorders. In the clinic, molecular imaging has the potential to improve early and differential diagnosis and to stratify and monitor therapy in these disorders. Meanwhile, in research, these techniques improve our understanding of the underlying pathophysiology and pathobiochemistry of these disorders and allow for drug testing. This article is an overview on our perspective on future developments in neurodegeneration tracers and the associated imaging technologies. For example, we predict that the current portfolio of β-amyloid and tau aggregate tracers will be improved and supplemented by tracers allowing imaging of other protein aggregation pathologies, such as α-synuclein and transactive response DNA binding protein 43 kDa. Future developments will likely also be observed in imaging neurotransmitter systems. This refers to both offering imaging to a broader population in cases involving the dopaminergic, cholinergic, and serotonergic systems and making possible the imaging of systems not yet explored, such as the glutamate and opioid systems. Tracers will be complemented by improved tracers of neuroinflammation and synaptic density. Technologywise, the use of hybrid PET/MRI, dedicated brain PET, and total-body PET scanners, as well as advanced image acquisition and processing protocols, will open doors toward broader and more efficient clinical use and novel research applications. Molecular imaging has the potential of becoming a standard and essential clinical and research tool to diagnose and study neurodegenerative disorders and to guide treatments. On that road, we will need to redefine the role of molecular imaging in relation to that of emerging blood-based biomarkers. Taken together, the unique features of molecular imaging-that is, the potential to provide direct noninvasive information on the presence, extent, localization, and quantity of molecular pathologic processes in the living body-together with the predicted novel tracer and imaging technology developments, provide optimism about a bright future for this approach to improved care and research on neurodegenerative disorders.

Effect of masupirdine (SUVN-502) on cognition in patients with moderate Alzheimer's disease: A randomized, double-blind, phase 2, proof-of-concept study

Introduction

This study explored the efficacy and safety of a serotonin-6 receptor antagonist, masupirdine, as adjunct treatment in patients with moderate Alzheimer's disease (AD) concomitantly treated with donepezil and memantine.

Methods

The effects of masupirdine were evaluated in patients with moderate AD dementia on background treatment with donepezil and memantine. Five hundred thirty-seven patients were expected to be randomized in a 1:1:1 ratio, using permuted blocked randomization. After a 2- to 4-week screening period, the study consisted of a 26-week double-blind treatment period, and a 4-week washout period. The primary efficacy measure was the 11-item cognitive subscale of the Alzheimer's Disease Assessment Scale (ADAS-Cog 11). Secondary efficacy measures were Clinical Dementia Rating Scale-Sum of Boxes, Mini-Mental State Examination, 23-item Alzheimer's Disease Co-operative Study Activities of Daily Living, and 12-item Neuropsychiatric Inventory. Changes from baseline were analyzed using a mixed effects model for repeated measures (MMRM). A total of 564 patients were randomized to receive either daily masupirdine 50 mg (190 patients), masupirdine 100 mg (185 patients), or placebo (189 patients). The study is registered at ClinicalTrials.gov (NCT02580305).

Results

The MMRM results showed statistically non-significant treatment differences in change from baseline in ADAS-Cog 11 scores at week 26, comparing each masupirdine dose arm to the placebo arm. No significant treatment effects were observed in the secondary evaluations.

Discussion

Masupirdine was generally safe and well tolerated. Possible reasons for the observed trial results are discussed.

Highlights

Masupirdine was evaluated in moderate Alzheimer's disease patients.First trial in class with background treatment of donepezil and memantine.Masupirdine was generally safe and well tolerated.Possible reasons for the observed trial results are discussed.

Electroconvulsive Therapy for Neuropsychiatric Symptoms due to Major Neurocognitive Disorder: A Prospective, Observational Study

OBJECTIVES

Neuropsychiatric symptoms (NPSs) in those with major neurocognitive disorder (MNCD) include the responsive behaviors of agitation and aggression. Electroconvulsive therapy (ECT) has shown some effectiveness based on retrospective studies and one open label prospective study. We hypothesized that ECT will reduce NPSs between baseline and after treatment in those with medication-refractory behaviors.

METHOD/DESIGN

This Canadian prospective multicenter study included MNCD patients admitted to geriatric psychiatry units for the management of refractory NPSs. All treatment-refractory participants suffered from advanced MNCD. We conducted the Neuropsychiatric Inventory-Clinician version and the Pittsburgh Agitation Scale at baseline, and during and after the ECT course. A bitemporal or bifrontal ECT series based on dose titration to 1.5 to 2.5 times seizure threshold was administered.

RESULTS

Data were collected for 33 patients with a mean age of 73 and categorized with severe MNCD using the Functional Assessment Staging of Alzheimer's Disease scale (stages 6 and 7). The data showed a drop in mean Neuropsychiatric Inventory-Clinician version from 58.36 to 24.58 (P < 0.0001). Mean Neuropsychiatric Inventory agitation subscale dropped from 7.12 to 3.09 (P = 0.007). Mean Neuropsychiatric Inventory aggression subscale dropped from 6.94 to 0.97 (P < 0.0001). There was a concomitant significant decline in Pittsburgh Agitation Scale scores. No participants dropped out because of intolerance of ECT. One participant died from pneumonia, which did not appear related to ECT.

CONCLUSIONS

In this naturalistic study, ECT was found to be a safe and effective treatment for certain NPSs in people with MNCD. This can translate into improving quality of life.

Behavioral and Psychological Symptoms of Dementia as a Means of Communication: Considerations for Reducing Stigma and Promoting Person-Centered Care

Dementia has rapidly become a major global health crisis. As the aging population continues to increase, the burden increases commensurately on both individual and societal levels. The behavioral and psychological symptoms of dementia (BPSD) are a prominent clinical feature of Alzheimer’s disease and related dementias (ADRD). BPSD represent a myriad of manifestations that can create significant challenges for persons living with dementia and their care providers. As such, BPSD can result in detriments to social interaction with others, resulting in harm to the psychosocial health of the person with dementia. While brain deterioration can contribute to BPSD as the disease progresses, it may be confounded by language and communication difficulties associated with ADRD. Indeed, when a person with dementia cannot effectively communicate their needs, including basic needs such as hunger or toileting, nor symptoms of pain or discomfort, it may manifest as BPSD. In this way, a person with dementia may be attempting to communicate with what little resources are available to them in the form of emotional expression. Failing to recognize unmet needs compromises care and can reduce quality of life. Moreover, failing to fulfill said needs can also deteriorate communication and social bonds with loved ones and caregivers. The aim of this review is to bring the differential of unmet needs to the forefront of BPSD interpretation for both formal and informal caregivers. The overarching goal is to provide evidence to reframe the approach with which caregivers view the manifestations of BPSD to ensure quality of care for persons with dementia. Understanding that BPSD may, in fact, be attempts to communicate unmet needs in persons with dementia may facilitate clinical care decisions, promote quality of life, reduce stigma, and foster positive communications.

CLINICAL NOTE: CEREBELLAR COGNITIVE AFFECTIVE SYNDROME IMPROVEMENT WITH SELECTIVE INHIBITOR OF SEROTONIN RECAPTATION

Cerebellar cognitive affective syndrome (CCAS) is characterized by alterations at the cognitive level (dysexecutive syndrome, visuospatial deficit, language ...), associated with affective / emotional changes. Its pathophysiology is not well known and there is currently no specific treatment. We describe a 64-year-old man with a rare condition of cognitive-behavioral disorder after an infarction in the left middle cerebral artery, dominated by executive dysfunctions, predominantly oral apraxia, interrupted divided attention, disturbed visuospatial organization and affective abnormalities with great apathy, and whose symptoms improved with a selective serotonin reuptake inhibitor (SSRI). In absence of cerebellar structural damage, a perfusion brain single photon emission computed tomography using 99mTc- hexamethyl-propylene-aminoxime (SPECT-HMPAO) showed left frontotemporal and parietoccipital hypoperfusion of known vascular etiology, and hypoperfusion in the right cerebellar hemisphere compatible with the phenomenon of crossed diaschisis. We hypothesize that cognitive and affective deficits are aggravated by the functional disruption of the reciprocal cerebellar interconnections with areas of cerebral association and paralimbic cortex, altering the contribution of the cerebellum to cognitive and affective processing and modulation. In the case described, both the clinical situation and the functional control images improved after treatment with SSRI, which increases the possibility that there is connectivity of some serotonergic transmission projections between cerebellum and contralateral association cortices, and that said connectivity dysfunctional is involved in the pathophysiology of CCAS.

Associations Between a Polymorphism in the Rat 5-HT1A Receptor Gene Promoter Region (rs198585630) and Cognitive Alterations Induced by Microwave Exposure

The nervous system is a sensitive target of electromagnetic radiation (EMR). Chronic microwave exposure can induce cognitive deficits, and 5-HT system is involved in this effect. Genetic polymorphisms lead to individual differences. In this study, we evaluated whether the single-nucleotide polymorphism (SNP) rs198585630 of 5-HT_1A receptor is associated with cognitive alterations in rats after microwave exposure with a frequency of 2.856 GHz and an average power density of 30 mW/cm². Rats were exposed to microwaves for 6 min three times a week for up to 6 weeks. PC12 cells and 293T cells were exposed to microwaves for 5 min up to 3 times at 2 intervals of 5 min. Transcriptional activity of 5-HT_1A receptor promoter containing rs198585630 C/T allele was determined in vitro. Electroencephalograms (EEGs), spatial learning and memory, and mRNA and protein expression of 5-HT_1A receptor were evaluated in vivo. We demonstrated that transcriptional activity of 5-HT_1A receptor promoter containing rs198585630 C allele was higher than that of 5-HT_1A receptor promoter containing T allele. The transcriptional activity of 5-HT_1A receptor promoter was stimulated by 30 mW/cm² microwave exposure, and rs198585630 C allele was more sensitive to microwave exposure, as it showed stronger transcriptional activation. Rats carrying rs198585630 C allele exhibited increased mRNA and protein expression of 5-HT_1A receptor and were more susceptible to 30 mW/cm² microwave exposure, showing cognitive deficits and inhibition of brain electrical activity. These findings suggest SNP rs198585630 of the 5-HT_1A receptor is an important target for further research exploring the mechanisms of hypersensitivity to microwave exposure.

Emotion Processing Dysfunction in Alzheimer's Disease: An Overview of Behavioral Findings, Systems Neural Correlates, and Underlying Neural Biology

We described behavioral studies to highlight emotional processing deficits in Alzheimer's disease (AD). The findings suggest prominent deficit in recognizing negative emotions, pronounced effect of positive emotion on enhancing memory, and a critical role of cognitive deficits in manifesting emotional processing dysfunction in AD. We reviewed imaging studies to highlight morphometric and functional markers of hippocampal circuit dysfunction in emotional processing deficits. Despite amygdala reactivity to emotional stimuli, hippocampal dysfunction conduces to deficits in emotional memory. Finally, the reviewed studies implicating major neurotransmitter systems in anxiety and depression in AD supported altered cholinergic and noradrenergic signaling in AD emotional disorders. Overall, the studies showed altered emotions early in the course of illness and suggest the need of multimodal imaging for further investigations. Particularly, longitudinal studies with multiple behavioral paradigms translatable between preclinical and clinical models would provide data to elucidate the time course and underlying neurobiology of emotion processing dysfunction in AD.

Development and crystallography-aided SAR studies of multifunctional BuChE inhibitors and 5-HT6R antagonists with β-amyloid anti-aggregation properties

The lack of an effective treatment makes Alzheimer's disease a serious healthcare problem and a challenge for medicinal chemists. Herein we report interdisciplinary research on novel multifunctional ligands targeting proteins and processes involved in the development of the disease: BuChE, 5-HT₆ receptors and β-amyloid aggregation. Structure-activity relationship analyses supported by crystallography and docking studies led to the identification of a fused-type multifunctional ligand 50, with remarkable and balanced potencies against BuChE (IC₅₀ = 90 nM) and 5-HT₆R (K_i = 4.8 nM), and inhibitory activity against Aβ aggregation (53% at 10 μM). In in vitro ADME-Tox and in vivo pharmacokinetic studies compound 50 showed good stability in the mouse liver microsomes, favourable safety profile and brain permeability with the brain to plasma ratio of 6.79 after p.o. administration in mice, thus being a promising candidate for in vivo pharmacology studies and a solid foundation for further research on effective anti-AD therapies.

Discovery of 1-(phenylsulfonyl)-1H-indole-based multifunctional ligands targeting cholinesterases and 5-HT6 receptor with anti-aggregation properties against amyloid-beta and tau

Multifunctional ligands as an essential variant of polypharmacology are promising candidates for the treatment of multi-factorial diseases like Alzheimer's disease. Based on clinical evidence and following the paradigm of multifunctional ligands we have rationally designed and synthesized a series of compounds targeting processes involved in the development of the disease. The biological evaluation led to the discovery of two compounds with favorable pharmacological characteristics and ADMET profile. Compounds 17 and 35 are 5-HT₆R antagonists (K_i = 13 nM and K_i = 15 nM respectively) and cholinesterase inhibitors with distinct mechanisms of enzyme inhibition. Compound 17, a tacrine derivative is a reversible inhibitor of acetyl- and butyrylcholinesterase (IC₅₀ = 8 nM and IC₅₀ = 24 nM respectively), while compound 35 with rivastigmine-derived phenyl N-ethyl-N-methylcarbamate fragment is a selective, pseudo-irreversible inhibitor of butyrylcholinesterase (IC₅₀ = 455 nM). Both compounds inhibit aggregation of amyloid β in vitro (75% for compound 17 and 68% for 35 at 10 μM) moreover, compound 35 is a potent tau aggregation inhibitor in cellulo (79%). In ADMET in vitro studies both compounds showed acceptable metabolic stability on mouse liver microsomes (28% and 60% for compound 17 and 35 respectively), no or little effect on CYP3A4 and 2D6 up to a concentration of 10 μM and lack of toxicity on HepG2 cell line (IC₅₀ values of 80 and 21 μM, for 17 and 35 respectively). Based on the pharmacological characteristics and favorable pharmacokinetic properties, we propose compounds 17 and 35 as an excellent starting point for further optimization and in-depth biological studies.

Psychedelic-inspired approaches for treating neurodegenerative disorders

Psychedelics are increasingly being recognized for their potential to treat a wide range of brain disorders including depression, post-traumatic stress disorder (PTSD), and substance use disorder. Their broad therapeutic potential might result from an ability to rescue cortical atrophy common to many neuropsychiatric and neurodegenerative diseases by impacting neurotrophic factor gene expression, activating neuronal growth and survival mechanisms, and modulating the immune system. While the therapeutic potential of psychedelics has not yet been extended to neurodegenerative disorders, we provide evidence suggesting that approaches based on psychedelic science might prove useful for treating these diseases. The primary target of psychedelics, the 5-HT_2A receptor, plays key roles in cortical neuron health and is dysregulated in Alzheimer's disease. Moreover, evidence suggests that psychedelics and related compounds could prove useful for treating the behavioral and psychological symptoms of dementia (BPSD). While more research is needed to probe the effects of psychedelics in models of neurodegenerative diseases, the robust effects of these compounds on structural and functional neuroplasticity and inflammation clearly warrant further investigation.

Psychedelics as Novel Therapeutics in Alzheimer's Disease: Rationale and Potential Mechanisms

Serotonin 2A receptor (5-HT_2AR) agonist "classic psychedelics" are drawing increasing interest as potential mental health treatments. Recent work suggests psychedelics can exert persisting anxiolytic and antidepressant effects lasting up to several months after a single administration. Data indicate acute subjective drug effects as important psychological factors involved in observed therapeutic benefits. Additionally, animal models have shown an important role for 5-HT_2AR agonists in modulating learning and memory function with relevance for Alzheimer's Disease (AD) and related dementias. A number of biological mechanisms of action are under investigation to elucidate 5-HT_2AR agonists' therapeutic potential, including enhanced neuroplasticity, anti-inflammatory effects, and alterations in brain functional connectivity. These diverse lines of research are reviewed here along with a discussion of AD pathophysiology and neuropsychiatric symptoms to highlight classic psychedelics as potential novel pharmacotherapies for patients with AD. Human clinical research suggests a possible role for high-dose psychedelic administration in symptomatic treatment of depressed mood and anxiety in early-stage AD. Preclinical data indicate a potential for low- or high-dose psychedelic treatment regimens to slow or reverse brain atrophy, enhance cognitive function, and slow progression of AD. In conclusion, rationale and potential approaches for preliminary research with psychedelics in patients with AD are presented, and ramifications of this line of investigation for development of novel AD treatments are discussed.

Improvement of cognitive performance by a nutraceutical formulation: Underlying mechanisms revealed by laboratory studies

Cognitive decline, decrease in neuronal function and neuronal loss that accompany normal aging and dementia are the result of multiple mechanisms, many of which involve oxidative stress. Herein, we review these various mechanisms and identify pharmacological and non-pharmacological approaches, including modification of diet, that may reduce the risk and progression of cognitive decline. The optimal degree of neuronal protection is derived by combinations of, rather than individual, compounds. Compounds that provide antioxidant protection are particularly effective at delaying or improving cognitive performance in the early stages of Mild Cognitive Impairment and Alzheimer's disease. Laboratory studies confirm alleviation of oxidative damage in brain tissue. Lifestyle modifications show a degree of efficacy and may augment pharmacological approaches. Unfortunately, oxidative damage and resultant accumulation of biomarkers of neuronal damage can precede cognitive decline by years to decades. This underscores the importance of optimization of dietary enrichment, antioxidant supplementation and other lifestyle modifications during aging even for individuals who are cognitively intact.

Inhibition of Astrocytic Histamine N-Methyltransferase as a Possible Target for the Treatment of Alzheimer's Disease

Alzheimer’s disease (AD) represents the principal cause of dementia among the elderly. Great efforts have been established to understand the physiopathology of AD. Changes in neurotransmitter systems in patients with AD, including cholinergic, GABAergic, serotoninergic, noradrenergic, and histaminergic changes have been reported. Interestingly, changes in the histaminergic system have been related to cognitive impairment in AD patients. The principal pathological changes in the brains of AD patients, related to the histaminergic system, are neurofibrillary degeneration of the tuberomammillary nucleus, the main source of histamine in the brain, low histamine levels, and altered signaling of its receptors. The increase of histamine levels can be achieved by inhibiting its degrading enzyme, histamine N-methyltransferase (HNMT), a cytoplasmatic enzyme located in astrocytes. Thus, increasing histamine levels could be employed in AD patients as co-therapy due to their effects on cognitive functions, neuroplasticity, neuronal survival, neurogenesis, and the degradation of amyloid beta (Aβ) peptides. In this sense, the evaluation of the impact of HNMT inhibitors on animal models of AD would be interesting, consequently highlighting its relevance.

5-HT7 receptors in Alzheimer's disease

Even though the involvement of serotonin (5-hydroxytryptamine; 5-HT) and its receptors in Alzheimer's disease (AD) is widely accepted, data on the expression and the role of 5-HT₇ receptors in AD is relatively limited. Therefore, the objective of the present work was to study the expression of serotonergic 5-HT₇ receptors in postmortem samples of AD brains and correlate it with neurotransmitter levels, cognition and behavior. The study population consisted of clinically well-characterized and neuropathologically confirmed AD patients (n = 42) and age-matched control subjects (n = 18). Reverse-transcription quantitative polymerase chain reaction (RT-qPCR) and high-performance liquid chromatography were performed on Brodmann area (BA) 7, BA10, BA22, BA24, hippocampus, amygdala, thalamus and cerebellum to measure mRNA levels of 5-HT₇ receptors (HTR7), as well as the concentrations of various monoamine neurotransmitters and their metabolites. Decreased levels of HTR7 mRNA were observed in BA10. A significant association was observed between HTR7 levels in BA10 and BEHAVE-AD cluster B (hallucinations) (rs(28) = 0.444, P < 0.05). In addition, a negative correlation was observed between HTR7 levels in BA10 and both MHPG concentrations in this brain region (rs(45) = -0.311; P < 0.05), and DOPAC levels in the amygdala (rs(42) = -0.311; P < 0.05). Quite surprisingly, no association was found between HTR7 levels and cognitive status. Altogether, this study supports the notion of the involvement of 5-HT₇ receptors in psychotic symptoms in AD, suggesting the interest of testing antagonist acting at this receptor to specifically treat psychotic symptoms in this illness.

Behavioral and Cognitive Response to Selective Serotonin Reuptake Inhibitors in Frontotemporal Lobar Degeneration: A Systematic Review and Meta-analysis

OBJECTIVE

This article systematically reviews current literature on the efficacy and efficiency of selective serotonin reuptake inhibitors (SSRIs) in the treatment of patients with frontotemporal lobar degeneration (FTLD), with a particular focus on behavior and cognitive functions.

METHODS

A search was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines using CENTRAL, MEDLINE, and Cochrane Library databases. Eleven randomized controlled trials and open-label studies looking at the effects of SSRIs on FTLD patients were included. A random-effects meta-analysis was performed, consisting of 3 randomized and controlled studies that used the neuropsychiatric inventory to assess SSRI intervention.

RESULTS

The meta-analysis shows a combined mean reduction of 10.17 points (95% confidence interval, 18.14-2.19; P = 0.01) on the neuropsychiatric inventory with SSRI treatment in FTLD patients. The I2 calculated for this study was 62% (P = 0.07), which represents moderate heterogeneity among the studies. The Egger regression test (P = 0.526) did not show a publication bias. Sensitivity analysis showed no significant change.

CONCLUSIONS

The current meta-analysis supports SSRIs as an intervention for management of behavioral symptoms of FTLD. Marked improvements were seen in disinhibition, irritability, aggression, and aberrant motor activity across studies. However, apathy/loss of empathy did not show similarly promising results. A deteriorative effect on cognition was seen associated with SSRI use.

When responsive and reactive meet organic? Treatment implications of language use in the era of #BanBPSD

The aetiopathogenesis of behaviours and psychological symptoms of dementia (BPSD) is often subjective, complex and multifaceted, produced by an array of contributing factors, including biomedical, psychological, environmental and/or social factors. Alongside other contributing factors, organic aetiology of BPSD should be considered when devising therapeutic management plans. Although considered last resort, time‐limited antipsychotic treatment (≤3 months) may have a vital adjunct role in managing intractable, refractory, distressing and/or life‐threatening BPSD, such as delusions and hallucinations; but only after person‐centred psychosocial interventions are exhausted and fail to deliver any therapeutic response. If prescribed, careful monitoring of therapeutic responses and adverse effects of antipsychotics with de‐prescribing plans should be a top priority, as these agents have limited efficacies and serious adverse outcomes (e.g., mortality).

Effects of olfactory stimulation on cognitive function and behavior problems in older adults with dementia: A systematic literature review

The aim of this study was to examine the effects of olfactory stimulation on both cognitive and behavioral symptoms in neurodegenerative diseases. The criteria for selection of participants in the study included neurodegenerative disease, interventions using olfactory stimulation, and measured cognitive or psychological symptoms. 5301 articles were identified, excluding duplicate papers. Seven original articles were selected according to the full article review and eligibility criteria. The final selected studies were all quasi-experimental studies and were published between 2002 and 2015. To assess the risk of bias, we used Cochrane Collaboration's tool, Non-randomized Studies-of Interventions (ROBINS-I). Although olfactory stimulation reported various effects on behavioral and psychological symptoms, it is still in its infancy. We propose standardization of olfactory stimulation and olfactory training. In patients with neurodegenerative diseases, it is necessary to consider the symptoms and severity of olfactory stimulation.

Behavioural disorders in Alzheimer's disease: the descriptive and predictive role of brain 18 F-fluorodesoxyglucose-positron emission tomography

BACKGROUND

Alzheimer's disease (AD) has a high incidence in the elderly. Besides cognitive disorders, patients may also develop behavioural and psychological symptoms of dementia (BPSD), which can be particularly disabling for patients and families. BPSD encompass a wide range of symptoms, among which psychotic symptoms and disruptive behaviours often prompt the first related hospitalization and request for family support. The aetiological mechanism of BPSD has not yet been clarified, and no predictive or risk factors have been identified. The main objectives of our study are to describe the frequency of aggression/agitation and psychotic symptoms, defined 'positive BPSD', in a cohort of 60 AD patients, identify areas of the brain involved in behavioural symptomatology through brain ¹⁸ F-fluorodesoxyglucose-positron emission tomography (FDG-PET), and investigate a potential predictive role of brain FDG-PET in BPSD development.

METHODS

A cohort of 60 AD patients was retrospectively enrolled and regularly followed for at least 3 years. Each subject underwent brain FDG-PET at the time of diagnosis. Patients were divided into three groups based on the presence of behavioural disturbances: present, absent, and developed later.

RESULTS

Of the 60 AD patients in the cohort, 52% had positive BPSD: 17 at baseline and 14 during the 3-year follow-up. FDG-PET identified an association between hypometabolism in the bilateral temporal lobes and the presence of BPSD, and showed initial hypometabolism in the postero-temporal lobes 3 years before symptom onset.

CONCLUSIONS

Positive BPSD are frequently manifested in AD. Our study identified the temporal lobes as the neurobiological substrate of positive BPSD and FDG-PET as a potential instument to predict their developement. Temporal lobes are involved in processing facial expression and recognizing emotions; an impairment of these functions could cause delusions and agitated/aggressive behaviour. To confirm the potential predictive role of FDG-PET in the onset of BPSD in AD, further studies are needed.

Personalizing the Care and Treatment of Alzheimer's Disease: An Overview

Alzheimer's disease (AD) is a progressive, complex, and multifactorial neurodegenerative disorder, still without effective and stable therapeutic strategies. Currently, available medications for AD are based on symptomatic therapy, which include acetylcholinesterase (AChE) inhibitors and N-methyl-D-aspartate (NMDA) receptor antagonist. Additionally, medications such as antipsychotic drugs, antidepressants, sedative, and hypnotic agents, and mood stabilizers are used for the management of behavioral and psychological symptoms of dementia (BPSD). Clinical research has been extensively investigated treatments focusing on the hallmark pathology of AD, including the amyloid deposition, tau hyperphosphorylation, neuroinflammation, and vascular changes; however, so far without success, as all new potential drugs failed to show significant clinical benefit. The underlying heterogeneous etiology and diverse symptoms of AD suggest that a precision medicine strategy is required, which would take into account the complex genetic, epigenetic, and environmental landscape of each AD patient. The article provides a comprehensive overview of the literature on AD, the current and potential therapy of both cognitive symptoms as well as BPSD, with a special focus on gut microbiota and epigenetic modifications as new emerging drug targets. Their specific patterns could represent the basis for novel individually tailored approaches aimed to optimize precision medicine strategies for AD prevention and treatment. However, the successful application of precision medicine to AD demands a further extensive research of underlying pathological processes, as well as clinical and biological complexity of this multifactorial neurodegenerative disorder.

Syndrome-Based Prescription to Optimize Psychotropics: Are CHROME Criteria a Game Changer?

A variety of medical and social factors have contributed over the last decades to the overuse of psychotropic drugs in people with dementia. One social factor is probably the frequent failure to provide adequate person-centered care, be it in the community or in institutional settings. This unfortunate reality has been reacted upon with numerous guidelines to reduce prescriptions of the most dangerous drugs (e.g., neuroleptics). Each psychotropic drug prescription can in principle be assessed around three dimensions: (a) adequate, (b) inadequate, and (c) chemical restraint. The CHemical Restraints avOidance MEthodology (CHROME) defined chemical restraint as any prescription based on organizational convenience, rather than justified with medical diagnosis. Two validation studies revealed that one of the main medical reasons of over- and miss-prescriptions was symptom-based prescription. By switching to syndrome-based prescription, a large proportion of drugs could be de-prescribed and some re-adjusted or kept. Paucity of research and weakness of data are not conclusive about the adequacy of specific drugs for the myriad of cases presented by patients with dementia and comorbid conditions. Clinical practice, however, leads us to believe that even under optimal care conditions, psychotropics might still contribute to quality of life if based on an adequate diagnosis. This article explains the rationale that underlies a syndromic approach aimed at optimizing psychotropic treatment in people with dementia whose significant suffering derives from their thought, affective, or behavioral problems. The results of previous validation studies of this new methodology will be discussed and conclusions for future results will be drawn.

Serotonin 2 Receptors, Agomelatine, and Behavioral and Psychological Symptoms of Dementia in Alzheimer's Disease

There are nearly 50 million Alzheimer's disease (AD) patients worldwide, 90% of whom develop behavioral and psychological symptoms of dementia (BPSD), which increase the mortality rate of patients, and impose an economic and care burden on families and society. As a neurotransmitter and neuromodulator, serotonin is involved in the regulation of psychoemotional, sleep, and feeding functions. Accumulating data support the importance of serotonin in the occurrence and development of BPSD. Studies have shown that reduction of serotonin receptors can increase depression and mental symptoms in AD patients. At present, there is no drug treatment for AD approved by the US Food and Drug Administration. Among them, agomelatine, as a new type of antidepressant, can act on serotonin 2 receptors to improve symptoms such as depression and anxiety. At present, research on BPSD is still in the preliminary exploratory stage, and there are still a lot of unknowns. This review summarizes the relationship between serotonin 2 receptors, agomelatine, and BPSD. It provides a new idea for the study of the pathogenesis and treatment of BPSD.

Behavioral and Psychological Symptoms in Dementia (BPSD) and the Use of Antipsychotics

Dementia affects about 47 million people worldwide, number expected to exponentially increase within 30 years. Alzheimer’s disease (AD) is the most common dementia type, accounting on its own for almost 70% of all dementia cases. Behavioral and psychological symptoms (BPSD) frequently occur during the disease progression; to treat agitation, aggressiveness, delusions and hallucinations, the use of antipsychotic drugs should be limited, due to their safety issues. In this literature review regarding the use of antipsychotics for treating BPSD in dementia, the advantages and limitation of antipsychotic drugs have been evaluated. The available medications for the management of behavioral and psychological symptoms are the antipsychotics, classed into typical and atypical, depending on their action on dopamine and serotonin receptors. First generation, or typical, antipsychotics exhibit lack of tolerability and display a broad range of side effects such as sedation, anticholinergic effects and extrapyramidal symptoms. Atypical, or second generation, antipsychotics bind more selectively to dopamine receptors and simultaneously block serotonin receptors, resulting in higher tolerability. High attention should be paid to the management of therapy interruption or switch between antipsychotics, to limit the possible rebound effect. Several switching strategies may be adopted, and clinicians should “tailor” therapies, accounting for patients’ symptoms, comorbidities, polytherapies and frailty.

Biological and Pharmacological Characterization of Ascorbic Acid and Nicotinamide Chitosan Nanoparticles against Insulin-Resistance-Induced Cognitive Defects: A Comparative Study

High consumption of industrialized food with high fat content is generally associated with insulin resistance, which in turn causes memory impairment and cognitive decline. Nicotinamide and ascorbic acid are among the promising neuroprotective molecules; however, an appreciable therapeutic activity necessitates the administration of a large dose of either. Therefore, the study aimed to assess if loading them in chitosan nanoparticles in doses 5-10 times lower than the unencapsulated forms would achieve comparable therapeutic results. Animals were fed a high-fat-high-fructose (HFHF) diet for 75 days. The vitamins in their conventional form (100 mg/kg) and the nanoparticles under investigation (10 and 20 mg/kg) were given orally concomitantly with the diet in the last 15 days. The intake of HFHF diet for 75 days led to an insulin-resistant state, with memory impairment, which was verified behaviorally through the object recognition test. This was accompanied by significant reduction in brain insulin-like growth factor 1 (IGF-1), increased acetylcholine esterase activity, increase in the serotonin and dopamine turnover ratio, and increase in oxidative stress and 8-OHdG, indicating cellular DNA fragmentation. Cellular energy was also decreased, and immunohistochemical examination verified the high immunoreactivity in both the cortex and hippocampus of the brain. The administration of nanoparticulated nicotinamide or ascorbic acid with a 10 times lesser dose than the unencapsulated forms managed to reverse all aforementioned harmful effects, with an even lesser immunoreactivity score than the unencapsulated form. Therefore, it can be concluded that nicotinamide or ascorbic acid chitosan nanoparticles can be recommended as daily supplements for neuroprotection in patients suffering from insulin resistance after conduction of clinical investigations.

Comparisons of neuroinflammation, microglial activation, and degeneration of the locus coeruleus-norepinephrine system in APP/PS1 and aging mice

BACKGROUND

The role of microglia in Alzheimer's disease (AD) pathogenesis is becoming increasingly important, as activation of these cell types likely contributes to both pathological and protective processes associated with all phases of the disease. During early AD pathogenesis, one of the first areas of degeneration is the locus coeruleus (LC), which provides broad innervation of the central nervous system and facilitates norepinephrine (NE) transmission. Though the LC-NE is likely to influence microglial dynamics, it is unclear how these systems change with AD compared to otherwise healthy aging.

METHODS

In this study, we evaluated the dynamic changes of neuroinflammation and neurodegeneration in the LC-NE system in the brain and spinal cord of APP/PS1 mice and aged WT mice using immunofluorescence and ELISA.

RESULTS

Our results demonstrated increased expression of inflammatory cytokines and microglial activation observed in the cortex, hippocampus, and spinal cord of APP/PS1 compared to WT mice. LC-NE neuron and fiber loss as well as reduced norepinephrine transporter (NET) expression was more evident in APP/PS1 mice, although NE levels were similar between 12-month-old APP/PS1 and WT mice. Notably, the degree of microglial activation, LC-NE nerve fiber loss, and NET reduction in the brain and spinal cord were more severe in 12-month-old APP/PS1 compared to 12- and 24-month-old WT mice.

CONCLUSION

These results suggest that elevated neuroinflammation and microglial activation in the brain and spinal cord of APP/PS1 mice correlate with significant degeneration of the LC-NE system.

Tetrahydrobiopterin Improves Recognition Memory in the Triple-Transgenic Mouse Model of Alzheimer's Disease, Without Altering Amyloid-β and Tau Pathologies

BACKGROUND

Alzheimer's disease (AD) is a multifactorial disease, implying that multi-target treatments may be necessary to effectively cure AD. Tetrahydrobiopterin (BH4) is an enzymatic cofactor required for the synthesis of monoamines and nitric oxide that also exerts antioxidant and anti-inflammatory effects. Despite its crucial role in the CNS, the potential of BH4 as a treatment in AD has never been scrutinized.

OBJECTIVE

Here, we investigated whether BH4 peripheral administration improves cognitive symptoms and AD neuropathology in the triple-transgenic mouse model of AD (3xTg-AD), a model of age-related tau and amyloid-β (Aβ) neuropathologies associated with behavior impairment.

METHODS

Non-transgenic (NonTg) and 3xTg-AD mice were subjected to a control diet (5% fat - CD) or to a high-fat diet (35% fat - HFD) from 6 to 13 months to exacerbate metabolic disorders. Then, mice received either BH4 (15 mg/kg/day, i.p.) or vehicle for ten consecutive days.

RESULTS

This sub-chronic administration of BH4 rescued memory impairment in 13-month-old 3xTg-AD mice, as determined using the novel object recognition test. Moreover, the HFD-induced glucose intolerance was completely reversed by the BH4 treatment in 3xTg-AD mice. However, the HFD or BH4 treatment had no significant impact on Aβ and tau neuropathologies.

CONCLUSION

Overall, our data suggest a potential benefit from BH4 administration against AD cognitive and metabolic deficits accentuated by HFD consumption in 3xTg-AD mice, without altering classical neuropathology. Therefore, BH4 should be considered as a candidate for drug repurposing, at least in subtypes of cognitively impaired patients experiencing metabolic disorders.