Neuropsychiatric symptoms in Alzheimer's disease: What might be associated brain circuits?

The mediating effect of the amygdala-frontal circuit on the association between depressive symptoms and cognitive function in Alzheimer's disease

Depressive symptoms occur commonly in Alzheimer's disease (AD). Although abnormalities in the amygdala-frontal circuit have been linked to emotional dysregulation and cognitive impairment, the neurological basis underlying these associations in AD patients with depressive symptoms (ADD) is unclear. We aimed to investigate the relationship between the amygdala-frontal circuit and depressive symptoms and cognitive function in ADD. We recruited 60 ADD, 60 AD patients without depressive symptoms (ADND), and 60 healthy controls (HC). Functional connectivity (FC) maps of the bilateral amygdala were compared. Fractional anisotropy (FA) of the amygdala-frontal circuit connected by the uncinate fasciculus (UF) was calculated using automated fiber quantification (AFQ). In addition, mediation analysis was performed to explore the effects of the amygdala-frontal circuit on the relationship between depressive symptoms and cognitive function. We found decreased bilateral amygdala FC with the inferior frontal gyrus (IFG) in the ADD group compared to the ADND and HC groups. Moreover, FA in the left frontal UF (nodes 64-97) was significantly lower in the ADD group than ADND group. Notably, amygdala-based FC with IFG and the left frontal UF FA mediated the relationship between depressive symptoms and cognitive function in ADD, with mediating effects ranging between 15 and 18%. Our study is the first to demonstrate the mediating effect of functional and microstructural abnormalities in the amygdala-frontal circuit in ADD. The findings suggest that the amygdala-frontal circuit may underlie emotional dysregulation in ADD, providing potential targets for treatment strategies.

Brexpiprazole for Agitation Associated With Dementia Due to Alzheimer's Disease

Alzheimer's disease (AD) is a prevalent neurodegenerative disease characterized by progressive cognitive and functional decline. Nearly all patients with AD develop neuropsychiatric symptoms (NPSs). Agitation is one of the most distressing and challenging NPS. Brexpiprazole is an oral antipsychotic and is the first approved pharmacologic agent in the United States for the treatment of agitation associated with dementia due to AD. Its effect is thought to be from its partial serotonin 5-HT1A and dopamine D2 receptor agonist activity and serotonin 5-HT2A receptor antagonism. Brexpiprazole is a maintenance medication, and it should not be used "as needed" or as a "PRN" treatment for breakthrough agitation. Brexpiprazole is a major substrate of CYP2D6 and CYP3A4. Dose adjustments may be required for drug interactions or impaired renal or hepatic function. Clinical trials found brexpiprazole 2 to 3 mg/d demonstrated significant improvements in agitation, with brexpiprazole showing an approximate 5-point greater reduction on change in the Cohen-Mansfield Agitation Inventory total score at week 12 from baseline compared with placebo. Brexpiprazole is generally well tolerated and safe, and common adverse reactions when used for this indication include dizziness, headaches, insomnia, nasopharyngitis, somnolence, and urinary tract infections. Like other antipsychotics used for agitation in AD, brexpiprazole is associated with higher mortality rates compared with placebo. In a long-term care setting, there are several considerations for its use. Benefits include an oral agent that is well tolerated and clinical data showing statistically significant effects on agitation. However, brexpiprazole has not been studied in head-to-head clinical trials against other antipsychotics, and there are differing opinions if the agitation score reductions translate to a clinically meaningful difference. The approval of brexpiprazole signals favorably for upcoming agents for this indication, including escitalopram and dextromethorphan-bupropion. Both escitalopram and dextromethorphan-bupropion are currently undergoing clinical trials.

Emotion regulation in people living with dementia and their spouses: the role of neuropsychiatric symptoms

OBJECTIVES

People with dementia (PwD) and their care partners (CP) may have difficulties in emotion regulation, and individual differences in emotion regulation may be related to PwD's neuropsychiatric symptoms. This study explores whether there is self-awareness of PwD's difficulties in emotion regulation and whether CP's emotion regulation relates to the PwD's neuropsychiatric symptoms, potentially revealing bias or interpersonal effects.

METHOD

We used data from the Wish Outcome Obstacle Plan Study with a sample of 45 PwD and their spousal CP (n = 90 individuals). Multivariate linear regression models were used to investigate the associations between the CP-reported neuropsychiatric symptoms in PwD and self-reports of emotion regulation in both dyad members, net of sociodemographic and health factors. Separate analyses were conducted for each neuropsychiatric subsyndrome and each domain of difficulties in emotion regulation.

RESULTS

Increasing severity of neuropsychiatric symptoms was associated with higher difficulties in emotion regulation in PwD (ß = 1.23, p < 0.05), but not with CP's difficulties in emotion regulation. When CP reported more severe neuropsychiatric symptoms in PwD, PwD reported that they had difficulties in accepting emotions, controlling impulses, goal-directed behaviors, and accessing emotion regulation strategies, but not in emotion awareness and clarification. Proxy-reports of hyperactivity and psychosis subsyndromes are significantly related to PwD's self-reported difficulties in emotion regulation.

CONCLUSION

PwD reported difficulties in emotion regulation at the early stage of dementia. Proxy-reported neuropsychiatric symptoms may capture PwD's emotion regulation capability and not be biased by CP's difficulties in emotion regulation.

Knockdown of microglial iron import gene, DMT1, worsens cognitive function and alters microglial transcriptional landscape in a sex-specific manner in the APP/PS1 model of Alzheimer's disease

Background

Microglial cell iron load and inflammatory activation are significant hallmarks of late-stage Alzheimer's disease (AD). In vitro, microglia preferentially upregulate the iron importer, divalent metal transporter 1 (DMT1, gene name Slc11a2) in response to inflammatory stimuli, and excess iron can augment cellular inflammation, suggesting a feed-forward loop between iron import mechanisms and inflammatory signaling. However, it is not understood whether microglial iron import mechanisms directly contribute to inflammatory signaling and chronic disease in vivo. These studies determined the effects of microglial-specific knockdown of Slc11a2 on AD-related cognitive decline and microglial transcriptional phenotype.

Methods

In vitro experiments and RT-qPCR were used to assess a role for DMT1 in amyloid-β-associated inflammation. To determine the effects of microglial Slc11a2 knockdown on AD-related phenotypes in vivo, triple-transgenic Cx3cr1 Cre - ERT2 ;Slc11a2 flfl;APP/PS1 + or - mice were generated and administered corn oil or tamoxifen to induce knockdown at 5-6 months of age. Both sexes underwent behavioral analyses to assess cognition and memory (12-15 months of age). Hippocampal CD11b + microglia were magnetically isolated from female mice (15-17 months) and bulk RNA-sequencing analysis was conducted.

Results

DMT1 inhibition in vitro robustly decreased Aβ-induced inflammatory gene expression and cellular iron levels in conditions of excess iron. In vivo, Slc11a2 KD APP/PS1 female, but not male, mice displayed a significant worsening of memory function in Morris water maze and a fear conditioning assay, along with significant hyperactivity compared to control WT and APP/PS1 mice. Hippocampal microglia from Slc11a2 KD APP/PS1 females displayed significant increases in Enpp2, Ttr, and the iron-export gene, Slc40a1, compared to control APP/PS1 cells. Slc11a2 KD cells from APP/PS1 females also exhibited decreased expression of markers associated with disease-associated microglia (DAMs), such as Apoe, Ctsb, Csf1, and Hif1α.

Conclusions

This work suggests a sex-specific role for microglial iron import gene Slc11a2 in propagating behavioral and cognitive phenotypes in the APP/PS1 model of AD. These data also highlight an association between loss of a DAM-like phenotype in microglia and cognitive deficits in Slc11a2 KD APP/PS1 female mice. Overall, this work illuminates an iron-related pathway in microglia that may serve a protective role during disease and offers insight into mechanisms behind disease-related sex differences.

Emerging therapies for treatment of agitation, psychosis, or apathy in Alzheimer's disease

INTRODUCTION

Agitation, psychosis, and apathy are prevalent and highly distressing neuropsychiatric symptoms (NPS) of Alzheimer's disease (AD) that have been linked to numerous negative outcomes, including increased mortality, worsened cognitive decline, and caregiver burden. Current treatments for AD-associated agitation, namely atypical antipsychotics, provide some benefits but may increase the risk of serious adverse events and death. Meanwhile, no pharmacotherapies have been approved by regulatory agencies for the treatment of psychosis or apathy in AD. Over the past decade, many new and repurposed drugs have emerged as potential therapeutic options for managing these challenging NPS.

AREAS COVERED

This review aims to provide a comprehensive summary of pharmacotherapies that have recently been investigated in phase 2 and 3 clinical trials for the treatment of agitation, psychosis, or apathy in AD.

EXPERT OPINION

Novel atypical antipsychotics, serotonergic antidepressants, cannabinoids, and dextromethorphan combination drugs have shown promising results for alleviating agitation. Pimavanserin appears to be the most effective emerging therapy for psychosis, while methylphenidate has demonstrated good efficacy for apathy. Further research on biomarkers of NPS severity and treatment response, as well as continued improvements in methodological approaches are needed to advance the field.

Unique transcriptional signatures correlate with behavioral and psychological symptom domains in Alzheimer's disease

Despite the significant burden, cost, and worse prognosis of Alzheimer's disease (AD) with behavioral and psychological symptoms of dementia (BPSD), little is known about the molecular causes of these symptoms. Using antemortem assessments of BPSD in AD, we demonstrate that individual BPSD can be grouped into 4 domain factors in our cohort: affective, apathy, agitation, and psychosis. Then, we performed a transcriptome-wide analysis for each domain utilizing bulk RNA-seq of post-mortem anterior cingulate cortex (ACC) tissues. Though all 4 domains are associated with a predominantly downregulated pattern of hundreds of differentially expressed genes (DEGs), most DEGs are unique to each domain, with only 22 DEGs being common to all BPSD domains, including TIMP1. Weighted gene co-expression network analysis (WGCNA) yielded multiple transcriptional modules that were shared between BPSD domains or unique to each domain, and NetDecoder was used to analyze context-dependent information flow through the biological network. For the agitation domain, we found that all DEGs and a highly associated transcriptional module were functionally enriched for ECM-related genes including TIMP1, TAGLN, and FLNA. Another unique transcriptional module also associated with the agitation domain was enriched with genes involved in post-synaptic signaling, including DRD1, PDE1B, CAMK4, and GABRA4. By comparing context-dependent changes in DEGs between cases and control networks, ESR1 and PARK2 were implicated as two high-impact genes associated with agitation that mediated significant information flow through the biological network. Overall, our work establishes unique targets for future study of the biological mechanisms of BPSD and resultant drug development.

The selfish network: how the brain preserves behavioral function through shifts in neuronal network state

Neuronal networks possess the ability to regulate their activity states in response to disruptions. How and when neuronal networks turn from physiological into pathological states, leading to the manifestation of neuropsychiatric disorders, remains largely unknown. Here, we propose that neuronal networks intrinsically maintain network stability even at the cost of neuronal loss. Despite the new stable state being potentially maladaptive, neural networks may not reverse back to states associated with better long-term outcomes. These maladaptive states are often associated with hyperactive neurons, marking the starting point for activity-dependent neurodegeneration. Transitions between network states may occur rapidly, and in discrete steps rather than continuously, particularly in neurodegenerative disorders. The self-stabilizing, metastable, and noncontinuous characteristics of these network states can be mathematically described as attractors. Maladaptive attractors may represent a distinct pathophysiological entity that could serve as a target for new therapies and for fostering resilience.

Neuroanatomical and neurocognitive correlates of delusion in Alzheimer's disease and mild cognitive impairment

BACKGROUND

Neuropsychiatric symptoms and delusions are highly prevalent among people with dementia. However, multiple roots of neurobiological bases and shared neural basis of delusion and cognitive function remain to be characterized. By utilizing a fine-grained multivariable approach, we investigated distinct neuroanatomical correlates of delusion symptoms across a large population of dementing illnesses.

METHODS

In this study, 750 older adults with mild cognitive impairment and Alzheimer's disease completed brain structural imaging and neuropsychological assessment. We utilized principal component analysis followed by varimax rotation to identify the distinct multivariate correlates of cortical thinning patterns. Five of the cognitive domains were assessed whether the general cognitive abilities mediate the association between cortical thickness and delusion.

RESULTS

The result showed that distributed thickness patterns of temporal and ventral insular cortex (component 2), inferior and lateral prefrontal cortex (component 1), and somatosensory-visual cortex (component 5) showed negative correlations with delusions. Subsequent mediation analysis showed that component 1 and 2, which comprises inferior frontal, anterior insula, and superior temporal regional thickness accounted for delusion largely through lower cognitive functions. Specifically, executive control function assessed with the Trail Making Test mediated the relationship between two cortical thickness patterns and delusions.

DISCUSSION

Our findings suggest that multiple distinct subsets of brain regions underlie the delusions among older adults with cognitive impairment. Moreover, a neural loss may affect the occurrence of delusion in dementia largely due to impaired general cognitive abilities.

Examining Frontal Lobe Asymmetry and Its Potential Role in Aggressive Behaviors in Early Alzheimer's Disease

Background

Neuropsychiatric symptoms (NPS) in patients with dementia lead to caregiver burdens and worsen the patient's prognosis. Although many neuroimaging studies have been conducted, the etiology of NPS remains complex. We hypothesize that brain structural asymmetry could play a role in the appearance of NPS.

Objective

This study explores the relationship between NPS and brain asymmetry in patients with Alzheimer's disease (AD).

Methods

Demographic and MRI data for 121 mild AD cases were extracted from a multicenter Japanese database. Brain asymmetry was assessed by comparing the volumes of gray matter in the left and right brain regions. NPS was evaluated using the Neuropsychiatric Inventory (NPI). Subsequently, a comprehensive assessment of the correlation between brain asymmetry and NPS was conducted.

Results

Among each NPS, aggressive NPS showed a significant correlation with asymmetry in the frontal lobe, indicative of right-side atrophy (r = 0.235, p = 0.009). This correlation remained statistically significant even after adjustments for multiple comparisons (p < 0.01). Post-hoc analysis further confirmed this association (p < 0.05). In contrast, no significant correlations were found for other NPS subtypes, including affective and apathetic symptoms.

Conclusions

The study suggests frontal lobe asymmetry, particularly relative atrophy in the right hemisphere, may be linked to aggressive behaviors in early AD. These findings shed light on the neurobiological underpinnings of NPS, contributing to the development of potential interventions.

Neuropsychiatric and Cognitive Symptoms: Two Sides of the Same Coin?

Neuropsychiatric symptoms (NPS) are increasingly being recognized as clinical markers for incipient dementia in Alzheimer's disease (AD dementia). NPS may reinforce cognitive impairment or decline and vice versa. Although NPS are frequent already in mild cognitive impairment, their mechanisms are poorly understood. It is unclear if they share biological mechanisms with cognitive symptoms and how they are associated to structural brain changes, but evidence suggests associations of NPS to cerebral atrophy. An additional NPS dimension in AD dementia concepts might add valuable information to detect patients at risk for AD dementia.

Associations Between Hyperactive Neuropsychiatric Symptoms and Brain Morphology in Mild Cognitive Impairment and Alzheimer's Disease

BACKGROUND

Hyperactive neuropsychiatric symptoms (NPS) (i.e., agitation, disinhibition, and irritability) are among the most challenging symptoms to manage in Alzheimer's disease (AD). However, their underlying brain correlates have been poorly studied.

OBJECTIVE

We aimed to investigate the associations between the total score of hyperactive NPS and brain structures in participants with AD, mild cognitive impairment (MCI), and cognitively normal older adults (CN).

METHODS

Neuropsychiatric and 3T MRI data from 216 AD, 564 MCI, and 660 CN participants were extracted from the Alzheimer's Disease Neuroimaging Initiative database. To define NPS and brain structures' associations, we fitted a general linear model (GLM) in two ways: 1) an overall GLM including all three groups (AD, MCI, CN) and 2) three pair-wise GLMs (AD versus MCI, MCI versus CN, AD versus CN). The cortical changes as a function of NPS total score were investigated using multiple regression analyses.

RESULTS

Results from the overall GLM include associations between 1) agitation and the right parietal supramarginal surface area in the MCI-CN contrast, 2) disinhibition and the cortical thickness of the right frontal pars opercularis and temporal inferior in the AD-MCI contrast, and 3) irritability and the right frontal pars opercularis, frontal superior, and temporal superior volumes in the MCI-CN contrast.

CONCLUSIONS

Our study shows that each hyperactive NPS is associated with distinct brain regions in AD, MCI, and CN (groups with different levels of cognitive performance). This suggests that each NPS is associated with a unique signature of brain morphology, including variations in volume, thickness, or area.

Repetitive transcranial magnetic stimulation for apathy in patients with neurodegenerative conditions, cognitive impairment, stroke, and traumatic brain injury: a systematic review

Background

We aimed to determine the effects and tolerability of repetitive transcranial magnetic stimulation (rTMS) on apathy in patients with neurodegenerative conditions, mild cognitive impairment (MCI), stroke, and traumatic brain injury (TBI) via systematic review.

Methods

We conducted a systematic search in major electronic health databases, including PubMed, Scopus, and PsycINFO, covering the period from inception to June 2023. Comparative clinical trials and cohort studies, and studies with before-after designs were considered for inclusion. We used the Cochrane Risk of Bias and the National Institutes of Health (NIH) tools to assess methodological quality.

Results

Out of 258 records identified, 14 studies met our eligibility criteria (11 randomized controlled trials (RCT) and 3 studies utilized before-and-after designs) with a total of 418 patients (overall female-to-male ratio 1:1.17) included in the review. The overall methodological quality of the included studies was assessed to be fair to good. The stimulation parameters used varied considerably across the studies. The summary findings of our review indicate the following observations on the effects of rTMS on apathy: (1) the results of all included studies in Alzheimer's disease investigating the effects of rTMS on apathy have consistently shown a positive impact on apathy; (2) the majority of studies conducted in Parkinson's disease have not found statistically significant results; (3) a single study (RCT) on patients with primary progressive aphasia demonstrated significant beneficial effects of rTMS on apathy; (4) the trials conducted on individuals with MCI yielded varying conclusions; (5) one study (RCT) in chronic stroke suggested that rTMS might have the potential to improve apathy; (6) one study conducted on individuals with mild TBI did not find a significant favorable association on apathy; and (7) the use of different rTMS protocols on the populations described is generally safe.

Conclusion

The feasibility of utilizing rTMS as a treatment for apathy has been suggested in this review. Overall, limited evidence suggests that rTMS intervention may have the potential to modify apathy among patients with AD, PPA, MCI and chronic stroke, but less so in PD and mild TBI. These findings require confirmation by larger, well-designed clinical trials.

Cortical Iron Accumulation as an Imaging Marker for Neurodegeneration in Clinical Cognitive Impairment Spectrum: A Quantitative Susceptibility Mapping Study

OBJECTIVE

Cortical iron deposition has recently been shown to occur in Alzheimer's disease (AD). In this study, we aimed to evaluate how cortical gray matter iron, measured using quantitative susceptibility mapping (QSM), differs in the clinical cognitive impairment spectrum.

MATERIALS AND METHODS

This retrospective study evaluated 73 participants (mean age ± standard deviation, 66.7 ± 7.6 years; 52 females and 21 males) with normal cognition (NC), 158 patients with mild cognitive impairment (MCI), and 48 patients with AD dementia. The participants underwent brain magnetic resonance imaging using a three-dimensional multi-dynamic multi-echo sequence on a 3-T scanner. We employed a deep neural network (QSMnet+) and used automatic segmentation software based on FreeSurfer v6.0 to extract anatomical labels and volumes of interest in the cortex. We used analysis of covariance to investigate the differences in susceptibility among the clinical diagnostic groups in each brain region. Multivariable linear regression analysis was performed to study the association between susceptibility values and cognitive scores including the Mini-Mental State Examination (MMSE).

RESULTS

Among the three groups, the frontal (P < 0.001), temporal (P = 0.004), parietal (P = 0.001), occipital (P < 0.001), and cingulate cortices (P < 0.001) showed a higher mean susceptibility in patients with MCI and AD than in NC subjects. In the combined MCI and AD group, the mean susceptibility in the cingulate cortex (β = -216.21, P = 0.019) and insular cortex (β = -276.65, P = 0.001) were significant independent predictors of MMSE scores after correcting for age, sex, education, regional volume, and APOE4 carrier status.

CONCLUSION

Iron deposition in the cortex, as measured by QSMnet+, was higher in patients with AD and MCI than in NC participants. Iron deposition in the cingulate and insular cortices may be an early imaging marker of cognitive impairment related neurodegeneration.

Heart rate variability and risk of agitation in Alzheimer's disease: the Atherosclerosis Risk in Communities Study

Agitation in Alzheimer's disease is common and may be related to impaired emotion regulation capacity. Heart rate variability, a proposed index of autonomic and emotion regulation neural network integrity, could be associated with agitation propensity in Alzheimer's disease. We used the Atherosclerosis Risk in Communities Study cohort data, collected over seven visits spanning over two decades, to investigate whether heart rate variability (change) was associated with agitation risk in individuals clinically diagnosed with dementia due to Alzheimer's disease. Agitation (absence/presence) at Visit 5, the primary outcome, was based on the Neuropsychiatric Inventory agitation/aggression subscale, or a composite score comprising the total number of agitation/aggression, irritability, disinhibition and aberrant motor behaviour subscales present. Visit 1-5 heart rate variability measures were the log-transformed root mean square of successive differences in R-R intervals and standard deviation of normal-to-normal R-R intervals obtained from resting, supine, standard 12-lead ECGs. To aid interpretability, heart rate variability data were scaled such that model outputs were expressed for each 0.05 log-unit change in heart rate variability (which approximated to the observed difference in heart rate variability with every 5 years of age). Among 456 participants who had dementia, 120 were clinically classified to have dementia solely attributable to Alzheimer's disease. This group showed a positive relationship between heart rate variability and agitation risk in regression models, which was strongest for measures of (potentially vagally mediated) heart rate variability change over the preceding two decades. Here, a 0.05 log-unit of heart rate variability change was associated with an up to 10-fold increase in the odds of agitation and around a half-unit increase in the composite agitation score. Associations persisted after controlling for participants' cognitive status, heart rate (change), sociodemographic factors, co-morbidities and medications with autonomic effects. Further confirmatory studies, incorporating measures of emotion regulation, are needed to support heart rate variability indices as potential agitation propensity markers in Alzheimer's disease and to explore underlying mechanisms as targets for treatment development.

Management of neuropsychiatric symptoms in dementia

PURPOSE OF REVIEW

The purpose is to review the results and clinical implications of recent studies of neuropathology in relation to neuropsychiatric symptoms (NPS) in Alzheimer's disease and related dementias, and discuss new therapeutic approaches based on evidence from clinical trials.

RECENT FINDINGS

In a large autopsy series from a national consortium, multiple neuropathologies of dementia subtypes were common and increased severity of specific NPS during life was associated with greater severity of neuropathology across diagnoses. Based on three clinical trials, brexpiprazole, which is an antipsychotic with dopamine and serotonin receptor partial agonism properties, was recently approved for the treatment of agitation in Alzheimer's dementia by the U.S. Food and Drug Administration (FDA). Its therapeutic profile indicates modest efficacy with high safety. Brexpiprazole has not been compared to other antipsychotics that are commonly prescribed to treat agitation in dementia, though none of them have been approved for this indication. Other drugs that showed positive results in Phase 2 trials are being tested in Phase 3 trials. These include cannabinoids and drug combinations that inhibit dextromethorphan metabolism peripherally, thereby increasing its bioavailability in the brain. Apathy is common in several types of dementia, and there is initial evidence that treatment with methylphenidate, a psychostimulant, may be efficacious with good tolerability.

SUMMARY

Greater understanding of the associations between NPS and dementia subtypes can improve clinical management of these disorders. In addition to the approval of brexpiprazole to treat agitation in Alzheimer's dementia, there is optimism about other medications based on ongoing clinical trials. Along with short-term improvement, altering the adverse impact on NPS on long-term prognosis remains an important challenge for the field.

Compulsive-like Behaviors in Amyloid-β 1-42-Induced Alzheimer's Disease in Mice Are Associated With Hippocampo-cortical Neural Circuit Dysfunction

Background

In addition to memory deficits, patients with Alzheimer's disease (AD) experience neuropsychiatric disturbances. Recent studies have suggested the association of obsessive-compulsive disorder with the early stages of AD. However, there is a lack of understanding of the neurobiological underpinnings of compulsive-like behaviors at the neuronal circuit level and their relationship with AD.

Methods

We have addressed this issue in an amyloid-β 1-42-induced mouse model of AD by studying compulsive-like behaviors. Next, we compared the hippocampal and medial prefrontal cortex (mPFC) local field potential pattern and coherence between these regions of control and AD mice. We also assessed the expression pattern of acetylcholine and glutamatergic signaling in these regions, using quantitative polymerase chain reaction.

Results

Our findings show that AD mice exhibit compulsive-like behaviors, as evidenced by enhanced marble burying, nest building, and burrowing. Furthermore, AD mice exhibited hippocampo-cortical circuit dysfunction demonstrated by decreased power of rhythmic oscillations at the theta (4-12 Hz) and gamma (25-50 Hz) frequencies in the hippocampus and mPFC, two functionally interconnected brain regions involved both in AD and compulsive behaviors. Importantly, coherence between the hippocampus and mPFC in the theta band of AD animals was significantly reduced. Furthermore, we found reduced cholinergic and glutamatergic neurotransmission in the hippocampus and mPFC of AD mice.

Conclusions

We conclude that the hippocampo-cortical functional alterations may play a significant role in mediating the compulsive-like behaviors observed in AD mice. These findings may help in understanding the underlying circuit mechanisms of obsessive-compulsive disorder-like phenotypes associated with AD.

Antioxidant, LC-MS Analysis, and Cholinesterase Inhibitory Potentials of Phoenix dactylifera Cultivar Khudari: An In Vitro Enzyme Kinetics and In Silico Study

We evaluated the therapeutic potentials of Khudari fruit pulp, a functional food and cultivar of Phoenix dactylifera, against neurological disorders. Our results demonstrate a good amount of phytochemicals (total phenolic content: 17.77 ± 8.21 µg GA/mg extract) with a high antioxidant potential of aqueous extract (DPPH assay IC50 = 235.84 ± 11.65 µg/mL) and FRAP value: 331.81 ± 4.56 µmol. Furthermore, the aqueous extract showed the marked inhibition of cell-free acetylcholinesterase (electric eel) with an IC50 value of 48.25 ± 2.04 µg/mL, and an enzyme inhibition kinetics study revealed that it exhibits mixed inhibition. Thereafter, we listed the 18 best-matched phytochemical compounds present in aqueous extract through LC/MS analysis. The computational study revealed that five out of eighteen predicted compounds can cross the BBB and exert considerable aqueous solubility. where 2-{5-[(1E)-3-methylbuta-1,3-dien-1-yl]-1H-indol-3-yl}ethanol (MDIE) indicates an acceptable LD50. value. A molecular docking study exhibited that the compounds occupied the key residues of acetylcholinesterase with ΔG range between -6.91 and -9.49 kcal/mol, where MDIE has ∆G: -8.67 kcal/mol, which was better than that of tacrine, ∆G: -8.25 kcal/mol. Molecular dynamics analyses of 100 ns supported the stability of the protein-ligand complexes analyzed through RMSD, RMSF, Rg, and SASA parameters. TRP_84 and GLY_442 are the most critical hydrophobic contacts for the complex, although GLU_199 is important for H-bonds. Prime/MM-GBSA showed that the protein-ligand complex formed a stable confirmation. These findings suggest that the aqueous extract of Khudari fruit pulp has significant antioxidant and acetylcholinesterase inhibition potentials, and its compound, MDIE, forms stably with confirmation with the target protein, though this fruit of Khudari dates can be a better functional food for the treatment of Alzheimer's disease. Further investigations are needed to fully understand the therapeutic role of this plant-based compound via in vivo study.

Physical Exercise as Disease-Modifying Alternative against Alzheimer's Disease: A Gut-Muscle-Brain Partnership

Alzheimer's disease (AD) is a common cause of dementia characterized by neurodegenerative dysregulations, cognitive impairments, and neuropsychiatric symptoms. Physical exercise (PE) has emerged as a powerful tool for reducing chronic inflammation, improving overall health, and preventing cognitive decline. The connection between the immune system, gut microbiota (GM), and neuroinflammation highlights the role of the gut-brain axis in maintaining brain health and preventing neurodegenerative diseases. Neglected so far, PE has beneficial effects on microbial composition and diversity, thus providing the potential to alleviate neurological symptoms. There is bidirectional communication between the gut and muscle, with GM diversity modulation and short-chain fatty acid (SCFA) production affecting muscle metabolism and preservation, and muscle activity/exercise in turn inducing significant changes in GM composition, functionality, diversity, and SCFA production. This gut-muscle and muscle-gut interplay can then modulate cognition. For instance, irisin, an exercise-induced myokine, promotes neuroplasticity and cognitive function through BDNF signaling. Irisin and muscle-generated BDNF may mediate the positive effects of physical activity against some aspects of AD pathophysiology through the interaction of exercise with the gut microbial ecosystem, neural plasticity, anti-inflammatory signaling pathways, and neurogenesis. Understanding gut-muscle-brain interconnections hold promise for developing strategies to promote brain health, fight age-associated cognitive decline, and improve muscle health and longevity.

A narrative review on mild behavioural impairment: an exploration into its scientific perspectives

In clinical practice, the admission of patients with late-onset psychological and behavioural symptoms is frequent, regardless of the presence or absence of cognitive decline. These symptoms commonly occur in the prodromal stage of dementia and can precede the onset of dementia. While the concept of Mild Cognitive Impairment (MCI) -which is defined as a level of cognitive impairment insufficient to impact daily functioning- is well established, the notion of Mild Behavioural Impairment (MBI) is not yet widely recognized. However, studies have demonstrated that the presence of MBI in both cognitively normal patients and individuals with MCI is associated with an increased risk of dementia progression. Thus, MBI may serve as a neurobehavioral indicator of pre-dementia risk states. This narrative review aims to discuss the evolution of the term, the relevant clinical aspects, and potential biomarkers that may contribute to the clinical definition of MBI. The objective is to assist clinicians in recognizing the diagnosis and differentiating it from psychiatric syndromes, as well as identifying possible etiologies of neurodegeneration.

siRNA drug delivery across the blood-brain barrier in Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disease with a few FDA-approved drugs that provide modest symptomatic benefits and only two FDA-approved disease-modifying treatments for AD. The advancements in understanding the causative genes and non-coding sequences at the molecular level of the pathophysiology of AD have resulted in several exciting research papers that employed small interfering RNA (siRNA)-based therapy. Although siRNA is being sought by academia and biopharma industries, several challenges still need to be addressed. We comprehensively report the latest advances in AD pathophysiology, druggable targets, ongoing clinical trials, and the siRNA-based approaches across the blood-brain barrier for addressing AD. This review describes the latest delivery systems employed to address this barrier. Critical insights and future perspectives on siRNA therapy for AD are also provided.

An Update on Apathy in Alzheimer's Disease

Apathy is a complex multi-dimensional syndrome that affects up to 70% of individuals with Alzheimer's disease (AD). Whilst many frameworks to define apathy in AD exist, most include loss of motivation or goal-directed behaviour as the central feature. Apathy is associated with significant impact on persons living with AD and their caregivers and is also associated with accelerated cognitive decline across the AD spectrum. Neuroimaging studies have highlighted a key role of fronto-striatial circuitry including the anterior cingulate cortex (ACC), orbito-frontal cortex (OFC) and associated subcortical structures. Importantly, the presence and severity of apathy strongly correlates with AD stage and neuropathological biomarkers of amyloid and tau pathology. Following from neurochemistry studies demonstrating a central role of biogenic amine neurotransmission in apathy syndrome in AD, recent clinical trial data suggest that apathy symptoms may improve following treatment with agents such as methylphenidate-which may have an important role alongside emerging non-pharmacological treatment strategies. Here, we review the diagnostic criteria, rating scales, prevalence, and risk factors for apathy in AD. The underlying neurobiology, neuropsychology and associated neuroimaging findings are reviewed in detail. Finally, we discuss current treatment approaches and strategies aimed at targeting apathy syndrome in AD, highlighting areas for future research and clinical trials in patient cohorts.

Impaired Emotion Recognition: A Potential Marker for Social Behavioral Problems in Patients With Amnestic Mild Cognitive Impairment and Early Alzheimer Disease?

OBJECTIVE

Emotion recognition, an important aspect of social cognition, can be impaired already in early Alzheimer disease dementia and amnestic mild cognitive impairment (aMCI) and may underly social behavioral changes, which can increase caregiver burden. However, social behavior is difficult to assess in outpatient settings. We evaluated whether impaired emotion recognition is related to proxy-rated social behavioral problems and thus can serve as a marker of these changes.

PATIENTS AND METHOD

Emotion recognition was assessed with Ekman 60 Faces Test (EFT-total, 6 separate emotions) in patients (n = 31 AD; n = 37 aMCI) and healthy controls (n = 60 HCs). Social behavioral problems were rated by proxies with the neuropsychiatric inventory (agitation, apathy, irritability, disinhibition, and a sum score). It tested whether EFT scores differed between patients with and without behavioral problems.

RESULTS

AD had worse EFT-total ( P <0.001), disgust ( P = 0.02), and fear ( P = 0.001) than HC, but not than aMCI, who did not differ from HC. AD displayed more disinhibition ( P < 0.05). EFT and neuropsychiatric inventory sum scores were not significantly correlated. Patients with apathy had lower EFT-total ( P = 0.02).

CONCLUSIONS

Measuring emotion recognition adds value: it is impaired in early neurodegeneration and associated with apathy but not necessarily related to overall changes in social behavior in this population.

Amygdala activity and amygdala-hippocampus connectivity: Metabolic diseases, dementia, and neuropsychiatric issues

With rapid aging of the population worldwide, the number of people with dementia is dramatically increasing. Some studies have emphasized that metabolic syndrome, which includes obesity and diabetes, leads to increased risks of dementia and cognitive decline. Factors such as insulin resistance, hyperglycemia, high blood pressure, dyslipidemia, and central obesity in metabolic syndrome are associated with synaptic failure, neuroinflammation, and imbalanced neurotransmitter levels, leading to the progression of dementia. Due to the positive correlation between diabetes and dementia, some studies have called it "type 3 diabetes". Recently, the number of patients with cognitive decline due to metabolic imbalances has considerably increased. In addition, recent studies have reported that neuropsychiatric issues such as anxiety, depressive behavior, and impaired attention are common factors in patients with metabolic disease and those with dementia. In the central nervous system (CNS), the amygdala is a central region that regulates emotional memory, mood disorders, anxiety, attention, and cognitive function. The connectivity of the amygdala with other brain regions, such as the hippocampus, and the activity of the amygdala contribute to diverse neuropathological and neuropsychiatric issues. Thus, this review summarizes the significant consequences of the critical roles of amygdala connectivity in both metabolic syndromes and dementia. Further studies on amygdala function in metabolic imbalance-related dementia are needed to treat neuropsychiatric problems in patients with this type of dementia.

Plasmon-activated water as a therapeutic strategy in Alzheimer's disease by altering gut microbiota

Gut microbiota (GM) are involved in the pathophysiology of Alzheimer's disease (AD) and might correlate to the machinery of the gut-brain axis. Alteration of the GM profiles becomes a potential therapy strategy in AD. Here, we found that plasmon-activated water (PAW) therapy altered GM profile and reduced AD symptoms in APPswe/PS1dE9 transgenic mice (AD mice). GM profile showed the difference between AD and WT mice. PAW therapy in AD mice altered GM profile and fecal microbiota transplantation (FMT) reproduced GM profile in AD mice. PAW therapy and FMT in AD mice reduced cognitive decline and amyloid accumulation by novel object recognition (NOR) test and amyloid PET imaging. Immunofluorescent staining and western blot analysis of β-amyloid (Aβ) and phosphorylated (p)-tau in the brain of AD mice were reduced in PAW therapy and FMT. The inflammatory markers, interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α and pro-inflammatory indicator of arginase-1/CD86 ratio were also reduced. Furthermore, immunohistochemistry (IHC) analysis of occludin and claudin-5 in the intestine and AXL in the brain were increased to correlate with the abundant GM in PAW therapy and FMT. Our results showed the machinery of gut-brain axis, and PAW might be a potential therapeutic strategy in AD.

Priorities for research on neuromodulatory subcortical systems in Alzheimer's disease: Position paper from the NSS PIA of ISTAART

The neuromodulatory subcortical system (NSS) nuclei are critical hubs for survival, hedonic tone, and homeostasis. Tau-associated NSS degeneration occurs early in Alzheimer's disease (AD) pathogenesis, long before the emergence of pathognomonic memory dysfunction and cortical lesions. Accumulating evidence supports the role of NSS dysfunction and degeneration in the behavioral and neuropsychiatric manifestations featured early in AD. Experimental studies even suggest that AD-associated NSS degeneration drives brain neuroinflammatory status and contributes to disease progression, including the exacerbation of cortical lesions. Given the important pathophysiologic and etiologic roles that involve the NSS in early AD stages, there is an urgent need to expand our understanding of the mechanisms underlying NSS vulnerability and more precisely detail the clinical progression of NSS changes in AD. Here, the NSS Professional Interest Area of the International Society to Advance Alzheimer's Research and Treatment highlights knowledge gaps about NSS within AD and provides recommendations for priorities specific to clinical research, biomarker development, modeling, and intervention. HIGHLIGHTS: Neuromodulatory nuclei degenerate in early Alzheimer's disease pathological stages. Alzheimer's pathophysiology is exacerbated by neuromodulatory nuclei degeneration. Neuromodulatory nuclei degeneration drives neuropsychiatric symptoms in dementia. Biomarkers of neuromodulatory integrity would be value-creating for dementia care. Neuromodulatory nuclei present strategic prospects for disease-modifying therapies.

A review of current evidence for mild behavioral impairment as an early potential novel marker of Alzheimer's disease

Mild behavioral impairment (MBI) is a neurobehavioral syndrome that occurs in the absence of cognitive impairment later in life (≥50 years of age). MBI is widespread in the pre-dementia stage and is closely associated with the progression of cognitive impairment, reflecting the neurobehavioral axis of pre-dementia risk states and complementing the traditional neurocognitive axis. Despite being the most common type of dementia, Alzheimer's disease (AD) does not yet have an effective treatment; therefore, early recognition and intervention are crucial. The Mild Behavioral Impairment Checklist is an effective tool for identifying MBI cases and helps identify people at risk of developing dementia. However, because the concept of MBI is still quite new, the overall understanding of it is relatively insufficient, especially in AD. Therefore, this review examines the current evidence from cognitive function, neuroimaging, and neuropathology that suggests the potential use of MBI as a risk indicator in preclinical AD.

Bioactive Metabolite from Endophytic Aspergillus versicolor SB5 with Anti-Acetylcholinesterase, Anti-Inflammatory and Antioxidant Activities: In Vitro and In Silico Studies

Endophytic fungi are a highly unpredictable group of microorganisms that can create a diverse range of secondary metabolites with biological activity. These metabolites enhance the host's ability to tolerate stress caused by various factors, such as disease, insects, pathogens, and herbivores. The secondary metabolites produced by endophytic fungi may have potential applications in agriculture, pharmacy, and medicine. The purpose of this study was to examine the anti-acetylcholinesterase activity of secondary metabolites extracted from endophytic fungi. Aspergillus versicolor SB5 was one of the many endophytic fungi isolated from Juncus rigidus and identified genetically with accession number ON872302. Our study utilized fermentation and microbial cultivation techniques to obtain secondary metabolites. During the course of our investigation, we isolated a compound called Physcion (C1) from the endophytic fungus Aspergillus versicolor SB5. We subsequently identified that C1 possesses inhibitory activity against COX-2 and LOX-1, with IC50 values of 43.10 and 17.54 µg/mL, respectively, making it an effective anti-inflammatory agent. Moreover, we found that C1 also exhibited potent anticholinesterase activity (86.9 ± 1.21%). In addition to these promising therapeutic properties, our experiments demonstrated that C1 possesses strong antioxidant capacity, as evidenced by its ability to scavenge DPPH, ABTS, O2 radicals, and NO and inhibit lipid peroxidation. To further investigate the molecular mechanisms underlying C1 pharmacological properties, we employed SwissADME web tools to predict the compound's ADME-related physicochemical properties and used Molecular Operating Environment and PyMOL for molecular docking studies.

Emotional Dysregulation in Mild Behavioral Impairment Is Associated with Reduced Cortical Thickness in the Right Supramarginal Gyrus

BACKGROUND

Mild behavioral impairment (MBI) has attracted attention as a possible precursor symptom of dementia, but its neural basis has not been fully investigated.

OBJECTIVE

We aimed to investigate the relationship between MBI and surface area, cortical thickness, and volume in the temporal and parietal lobes, which are strongly associated with dementia and emotional disorders.

METHODS

This retrospective study evaluated 123 participants: 90 with mild cognitive impairment (MCI), 13 with subjective cognitive decline (SCD), and 20 cognitively healthy (CH). Using analysis of covariance (ANCOVA) with sex, age, and MMSE score as covariates, cortical thickness, surface area, and volume in 10 regions were compared between groups with and without MBI. Groups with MBI emotional dysregulation were also compared with groups without MBI.

RESULTS

ANCOVA revealed significantly smaller cortical thickness in the MBI group's right parahippocampal (p = 0.01) and supramarginal gyri (p = 0.002). After multiple comparison correction, only the right supramarginal gyrus was significantly smaller (p = 0.02). When considering only MBI emotional dysregulation, the right parahippocampal and supramarginal gyrus' cortical thicknesses were significantly smaller in this MBI group (p = 0.03, 0.01). However, multiple comparison correction identified no significant differences (p = 0.14, 0.11).

CONCLUSION

Overall MBI and the emotional dysregulation domains were associated with reduced cortical thickness in the right parahippocampal and supramarginal gyri. Since neurodegeneration in the medial temporal and parietal lobe precedes early Alzheimer's disease (AD), MBI, particularly emotion dysregulation, may predict early AD below the diagnostic threshold.

Design, synthesis, and evaluation of hydrazones as dual inhibitors of ryanodine receptors and acetylcholinesterases for Alzheimer's disease

Alzheimer's disease (AD) implicates neuronal loss, plaque and neurofibrillary tangle formation, and disturbed neuronal Ca²⁺ homeostasis, which leads to severe dementia, memory loss, as well as thinking and behavioral perturbations that could ultimately lead to death. Calcium dysregulation and low acetylcholine levels are two main mechanisms implicated in Alzheimer's disease progression. Simultaneous inhibition of calcium oscillations (store overload-induced Ca²⁺ release [SOICR]) and acetylcholinesterase (AChE) by a single molecule may bring a new breath of hope for AD treatment. Here, we described some dantrolene derivatives as dual inhibitors of the ryanodine receptor and AChE. Two series of acylhydrazone/sulfonylhydrazone derivatives with aromaticgroup were designed and synthesized. In this study, the target compounds were evaluated for their ability to inhibit SOICR and AChE in vitro, using dantrolene and donepezil as positive controls. Compound 22a exhibited excellent and balanced inhibitory potency against SOICR (inhibition (%) = 90.1, IC₅₀ = 0.162 μM) and AChE (inhibition (%) = 93.5, IC₅₀ = 0.372 μM). Docking simulations showed that several preferred compounds could bind to the active sites of both the proteins, further validating the rationality of the design strategy. Potential therapeutic effects in AD were evaluated using the Barnes maze and Morris water maze tests, which demonstrated that compound 22a significantly improved memory and cognitive behavior in AD model mice. Moreover, it was also found that compound 22a could enhance synaptic strength by measuring hippocampal long-term potentiation (LTP) in brain slices. These results suggested that the introduction of a sulfonyl-hydrazone scaffold and aromatic substitution to dantrolene derivatives provided a useful template for the development of potential chemical entities against AD.

Neuropathological correlates of neuropsychiatric symptoms in dementia

INTRODUCTION

Neuropsychiatric symptoms (NPS) are common in Lewy body disease (LBD), but their etiology is poorly understood.

METHODS

In a population-based post mortem study neuropathological data was collected for Lewy body (LB) neuropathology, neurofibrillary tangles (NFT), amyloid beta burden, TDP-43, lacunar infarcts, cerebral amyloid angiopathy (CAA), and hyaline atherosclerosis. Post mortem interviews collected systematic information regarding NPS and cognitive status. A total of 1038 cases were included: no pathology (NP; n = 761), Alzheimer's disease (AD; n = 189), LBD (n = 60), and AD+LBD (n = 28).

RESULTS

Hallucinations were associated with higher LB Braak stages, while higher NFT Braak staging was associated with depression, agitation, and greater number of symptoms in the Neuropsychiatric Inventory. Cases with dual AD+LBD pathology had the highest risk of hallucinations, agitation, apathy, and total symptoms but a multiplicative interaction between these pathologies was not significant.

DISCUSSION

LB and AD pathology contribute differentially to NPS likely with an additive process contributing to the increased burden of NPS.

Apathy in Alzheimer's disease: A neurocircuitry based perspective

In addition to memory deficits and other cognitive disturbances, patients with Alzheimer's disease (AD) experience neuropsychiatric symptoms, notably apathy, which is a state of impaired motivation observed by deficits in goal directed behavior. Apathy is a multifaceted neuropsychiatric condition and appears to be a prognostic indicator, correlating with the progression of AD. Strikingly, recent studies point out that the neurodegenerative pathology of AD may drive apathy independent of cognitive decline. These studies also highlight that neuropsychiatric symptoms, in particular apathy, might manifest early in AD. Here, we review the current understanding of the neurobiological underpinnings of apathy as a neuropsychiatric symptom of AD. Specifically, we highlight the neural circuits and brain regions recognized to be correlated with the apathetic symptomatology. We also discuss the current evidence that supports the notion that apathy and cognitive deficits may develop as independent but concurrent phenomena driven by AD pathology, suggesting its efficacy as an additional outcome measure in Alzheimer's disease clinical trials. The current and prospective therapeutic interventions for apathy in AD from a neurocircuitry based perspective are also reviewed.

Neuroimaging of mild behavioral impairment: A systematic review

There are many neuroimaging studies of mild behavioral impairment (MBI), but the results have been somewhat inconsistent. Moreover, it remains unclear whether MBI is a risk factor or prodromal symptom of dementia. Therefore, a systematic review was conducted to summarize the results of neuroimaging studies of MBI and consider whether MBI is a prodromal symptom of dementia in terms of its neural correlates. A systematic review supported by a JSPS Grant-in-Aid for Scientific Research (C) was conducted using MBI neuroimaging studies identified using PubMed, PsycINFO, CINAHL, and Google Scholar on November 1, 2022. The inclusion criteria were (i) neuroimaging study; (ii) research on human subjects; (iii) papers written in English; and (iv) not a case study, review, book, comments, or abstract only. Joanna Briggs Institute critical appraisal checklists were used to assess the quality of selected studies, and 23 structural and functional imaging studies were ultimately included in the systematic review. The structural studies suggested an association of MBI with atrophy in the hippocampus, parahippocampal gyrus, entorhinal cortex, and temporal lobe, whereas the functional studies indicated involvement of an altered default mode network, frontoparietal control network, and salience network in MBI. A limitation in many studies was the use of region-of-interest analysis. The brain areas detected as neural correlates of MBI are considered to be alterations in the early stage of each dementia. Therefore, MBI may emerge against a background of pathological changes in dementia.

James A, Dupuis K, Cohen D. Developing a music-based digital therapeutic to help manage the neuropsychiatric symptoms of dementia

The greying of the world is leading to a rapid acceleration in both the healthcare costs and caregiver burden that are associated with dementia. There is an urgent need to develop new, easily scalable modalities of support. This perspective paper presents the theoretical background, rationale, and development plans for a music-based digital therapeutic to manage the neuropsychiatric symptoms of dementia, particularly agitation and anxiety. We begin by presenting the findings of a survey we conducted with key opinion leaders. The findings highlight the value of a music-based digital therapeutic for treating neuropsychiatric symptoms, particularly agitation and anxiety. We then consider the neural substrates of these neuropsychiatric symptoms before going on to evaluate randomized control trials on the efficacy of music-based interventions in their treatment. Finally, we present our development plans for the adaptation of an existing music-based digital therapeutic that was previously shown to be efficacious in the treatment of adult anxiety symptoms.

Functional connectivity and mild behavioral impairment in dementia-free elderly

Background

Mild behavioral impairment (MBI) is a syndrome that uses later-life emergent and persistent neuropsychiatric symptoms (NPS) to identify a group at high risk for incident dementia. MBI is associated with neurodegenerative disease markers in advance of syndromic dementia. Functional connectivity (FC) correlates of MBI are understudied and could provide further insights into mechanisms early in the disease course. We used resting-state functional magnetic resonance imaging (rs-fMRI) to test the hypothesis that FC within the default mode network (DMN) and salience network (SN) of persons with MBI (MBI+) is reduced, relative to those without (MBI-).

Methods

From two harmonized dementia-free cohort studies, using a score of ≥6 on the MBI Checklist to define MBI status, 32 MBI+ and 63 MBI- individuals were identified (mean age: 71.7 years; 54.7% female). Seed-based connectivity analysis was implemented in each MBI group using the CONN fMRI toolbox (v20.b), with the posterior cingulate cortex (PCC) as the seed region within the DMN and anterior cingulate cortex (ACC) as the seed within the SN. The average time series from the PCC and ACC were used to determine FC with other regions within the DMN (medial prefrontal cortex, lateral inferior parietal cortex) and SN (anterior insula, supramarginal gyrus, rostral prefrontal cortex), respectively. Age, sex, years of education, and Montreal Cognitive Assessment scores were included as model covariates. The false discovery rate approach was used to correct for multiple comparisons, with a p-value of .05 considered significant.

Results

For the DMN, MBI+ individuals exhibited reduced FC between the PCC and the medial prefrontal cortex, compared to MBI-. For the SN, MBI+ individuals exhibited reduced FC between the ACC and left anterior insula.

Conclusion

MBI in dementia-free older adults is associated with reduced FC in networks known to be disrupted in dementia. Our results complement the evidence linking MBI with Alzheimer's disease biomarkers.

Highlights

Resting-state functional magnetic resonance imaging was completed in 95 dementia-free persons from FAVR and COMPASS-ND studies.Participants were stratified by informant-rated Mild Behavioral Impairment Checklist (MBI-C) score, ≥6 for MBI+.MBI+ participants showed reduced functional connectivity (FC) within the default mode network and salience network.These FC changes are consistent with those seen in early-stage Alzheimer's disease.MBI may help identify persons with early-stage neurodegenerative disease.

Application of Marine Natural Products against Alzheimer's Disease: Past, Present and Future

Alzheimer's disease (AD), a neurodegenerative disease, is one of the most intractable illnesses which affects the elderly. Clinically manifested as various impairments in memory, language, cognition, visuospatial skills, executive function, etc., the symptoms gradually aggravated over time. The drugs currently used clinically can slow down the deterioration of AD and relieve symptoms but cannot completely cure them. The drugs are mainly acetylcholinesterase inhibitors (AChEI) and non-competitive N-methyl-D-aspartate receptor (NDMAR) antagonists. The pathogenesis of AD is inconclusive, but it is often associated with the expression of beta-amyloid. Abnormal deposition of amyloid and hyperphosphorylation of tau protein in the brain have been key targets for past, current, and future drug development for the disease. At present, researchers are paying more and more attention to excavate natural compounds which can be effective against Alzheimer's disease and other neurodegenerative pathologies. Marine natural products have been demonstrated to be the most prospective candidates of these compounds, and some have presented significant neuroprotection functions. Consequently, we intend to describe the potential effect of bioactive compounds derived from marine organisms, including polysaccharides, carotenoids, polyphenols, sterols and alkaloids as drug candidates, to further discover novel and efficacious drug compounds which are effective against AD.

Mild behavioral impairment linked to progression to Alzheimer's disease and cortical thinning in amnestic mild cognitive impairment

Background

Mild behavioral impairment (MBI) is a neurobehavioral syndrome characterized by later life emergence of sustained neuropsychiatric symptoms, as an at-risk state for dementia. However, the associations between MBI and a risk of progression to Alzheimer's disease (AD) and its neuroanatomical correlates in mild cognitive impairment (MCI) are still unclear.

Method

A total 1,184 older adults with amnestic MCI was followed for a mean of 3.1 ± 2.0 years. MBI was approximated using a transformation algorithm for the Neuropsychiatric Inventory at baseline. A two-step cluster analysis was used to identify subgroups of individuals with amnestic MCI based on profiles of 5 MBI domain symptoms (decreased motivation, affective dysregulation, impulse dyscontrol, social inappropriateness, abnormal perception/thought content). A Cox regression analysis was applied to investigate differences in the risk of progression to AD between subgroups. A subset of participants (n = 202) underwent 3D T1-weighted MRI scans at baseline and cortical thickness was compared between the subgroups of amnestic MCI patients.

Result

The cluster analysis classified the patients into 3 groups: (1) patients without any MBI domain symptoms (47.4%, asymptomatic group); (2) those with only affective dysregulation (29.4%, affective dysregulation group); (3) those with multiple MBI domain symptoms, particularly affective dysregulation, decreased motivation and impulse dyscontrol (23.2%, complex group). Compared to the asymptomatic group, the complex group was associated with a higher risk of progression to AD (hazard ratio = 2.541 [1.904-3.392], p < 0.001), but the affective dysregulation group was not (1.214 [0.883-1.670], p = 0.232). In cortical thickness analysis, the complex group revealed cortical thinning bilaterally in the inferior parietal, lateral occipital, lateral superior temporal, and frontopolar regions compared with the affective dysregulation group.

Conclusion

The multiple co-occuring MBI domains in individuals with amnestic MCI are associated with a higher risk of progression to AD and cortical thinning in temporal, parietal and frontal areas. These results suggest that evaluation of MBI could be useful for risk stratification for AD and appropriate intervention in MCI individuals.

Effects of Pharmacological Treatments in Alzheimer's Disease: Permutation Entropy-Based EEG Complexity Study

Alzheimer's disease (AD) is a neurodegenerative brain disease affecting cognitive and physical functioning. The currently available pharmacological treatments for AD mainly contain cholinesterase inhibitors (AChE-I) and N-methyl-D-aspartic acid (NMDA) receptor antagonists (i.e., memantine). Because brain signals have complex nonlinear dynamics, there has been an increase in interest in researching complexity changes in the time series of brain signals in individuals with AD. In this study, we explore the electroencephalographic (EEG) complexity for making better observation of pharmacological therapy-based treatment effects on AD patients using the permutation entropy (PE) method. We examined EEG sub-band (delta, theta, alpha, beta, and gamma) complexity in de-novo, monotherapy (AChE-I), dual therapy (AChE-I and memantine) receiving AD participants compared with healthy elderly controls. We showed that each frequency band depicts its own complexity profile, which is regionally altered between groups. These alterations were also found to be associated with global cognitive scores. Overall, our findings indicate that entropy measures could be useful to show medication effects in AD.

Intranasal interferon-beta alleviates anxiety and depressive-like behaviors by modulating microglia polarization in an Alzheimer's disease model

Alzheimer's disease (AD) patients frequently experience neuropsychiatric symptoms (NPS), which are linked to a lower quality of life and a faster rate of disease progression. A growing body of research indicates that several microglial phenotypes control the inflammatory response and are crucial in the pathophysiology of AD-related NPS. Given the crucial role played by inflammatory mediators produced by microglia in developing of NPS, interferon-beta (IFNβ), a cytokine with anti-inflammatory capabilities, maybe a successful treatment for NPS caused by AD. In this investigation, using a rat model of AD, we examined the impact of intranasal treatment of IFNβ on anxious/depressive-like behavior and microglial M1/M2 polarization. The rat hippocampus was bilaterally injected with lentiviruses harboring mutant human amyloid precursor protein. Rats were given recombinant IFNβ1a (68,000 IU/rat) via the intranasal route, starting on day 23 following viral infection and continuing until day 49. On days 47-49, the elevated plus maze, forced swim, and tail suspension tests were applied to measure anxiety- and depressive-like behavior. Additionally, qPCR was utilized to quantify the expression of M1 markers (CD68, CD86, and CD40) and M2 markers (Ym1, CD206, Arg1, GDNF, BDNF, and SOCS1). Our findings demonstrated that decreased M2 marker expression is accompanied by anxious/depressive-like behavior when the mutant human APP gene is overexpressed in the hippocampus. In the rat model of AD, IFNβ therapy reduces anxious/depressive-like behaviors, at least in part by polarizing microglia towards M2. Therefore, IFNβ may be a viable therapeutic drug for reducing NPS in the context of AD.

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.

DIFFERENT METABOLIC AND CLINICAL PROFILES BETWEEN PATIENTS WITH PURE ALZHEIMER DEMENTIA AND EPILEPTIC ALZHEIMER DEMENTIA : A METABOLIC STUDY

Aim: To investigate the clinical characteristics and cerebral FDG PET metabolisms of dementia patients who also diagnosed with epilepsy and compare the differences between with the pure Alzheimer dementia patients. Methods: In this case-control study, a total of 14 patients; 7 patients with pure Alzheimer disease as a control group and 7 age and gender matched patients with Alzheimer disease and concomitant epilepsy as a study group were included. Detailed neurocognitive battery and brain fludeoxyglucose positron emission tomography (FDG PET-CT) were performed for all subjects. Results: In comparison of neurocognitive test scores, there was no significant difference between study and control groups. However, geriatric depression scale scores were significantly lower in study group than the controls (p= 0.026). In cerebral FDG-PET CT profiles of subjects we detected significantly lower metabolism in left and right cerebellum, left lentiform nucleus, right thalamus and vermis in the study group (p=0.008, p=0.023, p=0.003, p=0.002, p=0.002, respectively). In the right parietotemporal cortex and right and left associative visual cortex, we found higher metabolism in the study group than controls ( p=0.023, p=0.012, p=0.003, respectively). Conclusion: Epileptic patients with Alzheimer dementia may have distinct clinical and metabolic profile than pure Alzheimer disease patients. Even if there is no difference in the neurocognitive clinical scores of the patients, depression and related functional abnormalities may be a biomarker of epileptic AD.

Loss of Cholinergic Receptor Muscarinic 1 (CHRM1) Protein in the Hippocampus and Temporal Cortex of a Subset of Individuals with Alzheimer’s Disease, Parkinson’s Disease, or Frontotemporal Dementia: Implications for Patient Survival

Background: Dysfunction of cholinergic neurotransmission is a hallmark of Alzheimer’s disease (AD); forming the basis for using acetylcholine (ACh) esterase (AChE) inhibitors to mitigate symptoms of ACh deficiency in AD. The Cholinergic Receptor Muscarinic 1 (CHRM1) is highly expressed in brain regions impaired by AD. Previous analyses of postmortem AD brains revealed unaltered CHRM1 mRNA expression compared to normal brains. However, the CHRM1 protein level in AD and other forms of dementia has not been extensively studied. Reduced expression of CHRM1 in AD patients may explain the limited clinical efficacy of AChE inhibitors. Objective: To quantify CHRM1 protein in the postmortem hippocampus and temporal cortex of AD, Parkinson’s disease (PD), and frontotemporal dementia (FTD) patients. Methods: Western blotting was performed on postmortem hippocampus (N = 19/73/7/9: unaffected/AD/FTD/PD) and temporal cortex (N = 9/74/27: unaffected/AD/PD) using a validated anti-CHRM1 antibody. Results: Quantification based on immunoblotting using a validated anti-CHRM1 antibody revealed a significant loss of CHRM1 protein level (<50%) in the hippocampi (78% AD, 66% PD, and 85% FTD) and temporal cortices (56% AD and 42% PD) of dementia patients. Loss of CHRM1 in the temporal cortex was significantly associated with early death (<65–75 years) for both AD and PD patients. Conclusion: Severe reduction of CHRM1 in a subset of AD and PD patients can explain the reported low efficacy of AChE inhibitors as a mitigating treatment for dementia patients. Based on this study, it can be suggested that future research should prioritize therapeutic restoration of CHRM1 protein levels in cholinergic neurons.

Hippocampal morphological atrophy and distinct patterns of structural covariance network in Alzheimer's disease and mild cognitive impairment

Elucidating distinct morphological atrophy patterns of Alzheimer's disease (AD) and its prodromal stage, namely, mild cognitive impairment (MCI) helps to improve early diagnosis and medical intervention of AD. On that account, we aimed to obtain distinct patterns of voxel-wise morphological atrophy and its further perturbation on structural covariance network in AD and MCI compared with healthy controls (HCs). T1-weighted anatomical images of matched AD, MCI, and HCs were included in this study. Gray matter volume was obtained using voxel-based morphometry and compared among three groups. In addition, structural covariance network of identified brain regions exhibiting morphological difference was constructed and compared between pairs of three groups. Thus, patients with AD have a reduced hippocampal volume and an increased rate of atrophy compared with MCI and HCs. MCI exhibited a decreased trend in bilateral hippocampal volume compared with HCs and the accelerated right hippocampal atrophy rate than HCs. In AD, the hippocampus further exhibited increased structural covariance connected to reward related brain regions, including the anterior cingulate cortex, the putamen, the caudate, and the insula compared with HCs. In addition, the patients with AD exhibited increased structural covariance of left hippocampus with the bilateral insula, the inferior frontal gyrus, the superior temporal gyrus, and the cerebellum than MCI. These results reveal distinct patterns of morphological atrophy in AD and MCI, providing new insights into pathology of AD.

Psychosis as a Treatment Target in Dementia: A Roadmap for Designing Interventions

Psychotic phenomena are among the most severe and disruptive symptoms of dementias and appear in 30% to 50% of patients. They are associated with a worse evolution and great suffering to patients and caregivers. Their current treatments obtain limited results and are not free of adverse effects, which are sometimes serious. It is therefore crucial to develop new treatments that can improve this situation. We review available data that could enlighten the future design of clinical trials with psychosis in dementia as main target. Along with an explanation of its prevalence in the common diseases that cause dementia, we present proposals aimed at improving the definition of symptoms and what should be included and excluded in clinical trials. A review of the available information regarding the neurobiological basis of symptoms, in terms of pathology, neuroimaging, and genomics, is provided as a guide towards new therapeutic targets. The correct evaluation of symptoms is transcendental in any therapeutic trial and these aspects are extensively addressed. Finally, a critical overview of existing pharmacological and non-pharmacological treatments is made, revealing the unmet needs, in terms of efficacy and safety. Our work emphasizes the need for better definition and measurement of psychotic symptoms in dementias in order to highlight their differences with symptoms that appear in non-dementing diseases such as schizophrenia. Advances in neurobiology should illuminate the development of new, more effective and safer molecules for which this review can serve as a roadmap in the design of future clinical trials.

Network analysis of impulse dyscontrol in mild cognitive impairment and subjective cognitive decline

OBJECTIVES

To investigate conditional dependence relationships of impulse dyscontrol symptoms in mild cognitive impairment (MCI) and subjective cognitive decline (SCD).

DESIGN

A prospective, observational study.

PARTICIPANTS

Two hundred and thirty-five patients with MCI (n = 159) or SCD (n = 76) from the Prospective Study for Persons with Memory Symptoms dataset.

MEASUREMENTS

Items of the Mild Behavioral Impairment Checklist impulse dyscontrol subscale.

RESULTS

Stubbornness/rigidity, agitation/aggressiveness, and argumentativeness were frequent and the most central symptoms in the network. Impulsivity, the fourth most central symptom in the network, served as the bridge between these common symptoms and less central and rare symptoms.

CONCLUSIONS

Impulse dyscontrol in at-risk states for dementia is characterized by closely connected symptoms of irritability, agitation, and rigidity. Compulsions and difficulties in regulating rewarding behaviors are relatively isolated symptoms.

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.

Regional Cerebral Blood Flow Correlates of Neuropsychiatric Symptom Domains in Early Alzheimer’s Disease

Although various neuropsychiatric symptoms are frequently accompanied with Alzheimer’s disease (AD) and pose a substantial burden to both patients and caregivers, their neurobiological underpinnings remain unclear. This study investigated associations between regional cerebral blood flow (rCBF) and neuropsychiatric symptom domains in early AD. A total of 59 patients with early AD underwent brain technetium-99m hexamethylpropylene amine oxime (99mTc-HMPAO) single-photon emission computed tomography (SPECT) scans. Neuropsychiatric symptoms were assessed by the Neuropsychiatric Inventory and clustered into the affective, apathy, hyperactivity, and psychotic domains. A voxel-wise multiple regression analysis was performed with four domain scores as independent variables and age, sex, and Mini-Mental State Examination scores as covariates. The affective domain score was negatively correlated with rCBF in the prefrontal cortex, thalamus, and caudate. The apathy domain score showed inverse correlations with rCBF in the prefrontal and pre/postcentral gyri and midbrain. Patients with higher hyperactivity domain scores had increased rCBF in the prefrontal and temporal lobes. The psychotic symptom domain was positively correlated with rCBF in the cuneus and negatively associated with rCBF in the prefrontal, cingulate, and occipital regions and putamen. The score of each neuropsychiatric symptom domain showed the differential correlates of brain perfusion, while altered rCBF in the prefrontal cortex was found in all domains. Although preliminary, our results may suggest common and distinct patterns of rCBF underlying neuropsychiatric symptoms in early AD. Further studies with larger samples and control participants are warranted to confirm these findings.

Behavioral and Psychological Symptoms of Dementia in Different Dementia Disorders: A Large-Scale Study of 10,000 Individuals

Background:

The majority of individuals with dementia will suffer from behavioral and psychological symptoms of dementia (BPSD). These symptoms contribute to functional impairment and caregiver burden.

Objective:

To characterize BPSD in Alzheimer’s disease (AD), vascular dementia (VaD), mixed (Mixed) dementia, Parkinson’s disease dementia (PDD), dementia with Lewy bodies (DLB), frontotemporal dementia (FTD), and unspecified dementia in individuals residing in long-term care facilities.

Methods:

We included 10,405 individuals with dementia living in long-term care facilities from the Swedish registry for cognitive/dementia disorders (SveDem) and the Swedish BPSD registry. BPSD was assessed with the Neuropsychiatric Inventory - Nursing Home Version (NPI-NH). Multivariate logistic regression models were used to evaluate the associations between dementia diagnoses and different BPSDs.

Results:

The most common symptoms were aberrant motor behavior, agitation, and irritability. Compared to AD, we found a lower risk of delusions (in FTD, unspecified dementia), hallucinations (FTD), agitation (VaD, PDD, unspecified dementia), elation/euphoria (DLB), anxiety (Mixed, VaD, unspecified dementia), disinhibition (in PDD), irritability (in DLB, FTD, unspecified dementia), aberrant motor behavior (Mixed, VaD, unspecified dementia), and sleep and night-time behavior changes (unspecified dementia). Higher risk of delusions (DLB), hallucinations (DLB, PDD), apathy (VaD, FTD), disinhibition (FTD), and appetite and eating abnormalities (FTD) were also found in comparison to AD.

Conclusion:

Although individuals in our sample were diagnosed with different dementia disorders, they all exhibited aberrant motor behavior, agitation, and irritability. This suggests common underlying psychosocial or biological mechanisms. We recommend prioritizing these symptoms while planning interventions in long-term care facilities.

A transdiagnostic review of neuroimaging studies of apathy and disinhibition in dementia

Apathy and disinhibition are common and highly distressing neuropsychiatric symptoms associated with negative outcomes in persons with dementia. This paper is a critical review of functional and structural neuroimaging studies of these symptoms transdiagnostically in dementia of the Alzheimer type, which is characterized by prominent amnesia early in the disease course, and behavioural variant frontotemporal dementia, characterized by early social-comportmental deficits. We describe the prevalence and clinical correlates of these symptoms and describe methodological issues, including difficulties with symptom definition and different measurement instruments. We highlight the heterogeneity of findings, noting however, a striking similarity of the set of brain regions implicated across clinical diagnoses and symptoms. These regions involve several key nodes of the salience network, and we describe the functions and anatomical connectivity of these brain areas, as well as present a new theoretical account of disinhibition in dementia. Future avenues for research are discussed, including the importance of transdiagnostic studies, measuring subdomains of apathy and disinhibition, and examining different units of analysis for deepening our understanding of the networks and mechanisms underlying these extremely distressing symptoms.