Biomarkers of agitation and aggression in Alzheimer's disease: A systematic review

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.

Anesthetic-loaded nanodroplets with focused ultrasound reduces agitation in Alzheimer's mice

OBJECTIVE

Alzheimer's disease (AD) is often associated with neuropsychiatric symptoms, including agitation and aggressive behavior. These symptoms increase with disease severity, ranging from 10% in mild cognitive impairment to 50% in patients with moderate-to-severe AD, pose a great risk for self-injury and injury to caregivers, result in high rates of institutionalization and great suffering for patients and families. Current pharmacological therapies have limited efficacy and a high potential for severe side effects. Thus, there is a growing need to develop novel therapeutics tailored to safely and effectively reduce agitation and aggressive behavior in AD. Here, we investigate for the first time the use of focused ultrasound combined with anesthetic-loaded nanodroplets (nanoFUS) targeting the amygdala (key structure in the neurocircuitry of agitation) as a novel minimally invasive tool to modulate local neural activity and reduce agitation and aggressive behavior in the TgCRND8 AD transgenic mice.

METHODS

Male and female animals were tested in the resident-intruder (i.e., aggressive behavior) and open-field tests (i.e., motor agitation) for baseline measures, followed by treatment with active- or sham-nanoFUS. Behavioral testing was then repeated after treatment.

RESULTS

Active-nanoFUS neuromodulation reduced aggressive behavior and agitation in male mice, as compared to sham-treated controls. Treatment with active-nanoFUS increased the time male mice spent in social-non-aggressive behaviors.

INTERPRETATION

Our results show that neuromodulation with active-nanoFUS may be a potential therapeutic tool for the treatment of neuropsychiatric symptoms, with special focus on agitation and aggressive behaviors. Further studies are necessary to establish cellular, molecular and long-term behavioral changes following treatment with nanoFUS.

Empirical and Authoritative Classification of Neuropsychiatric Syndromes in Neurocognitive Disorders

Neuropsychiatric symptoms of neurocognitive disorders have been classified into higher-order constructs, often called neuropsychiatric syndromes. As with the general psychopathology literature, these classifications have been achieved through two approaches: empirical and authoritative. The authoritative approach relies on expert panels that condense the available evidence into operational criteria, whereas the empirical approach uses statistical methods to discover symptom patterns and possible hierarchies formed by them. In this article, the author reviews the strengths and weaknesses of both approaches using general psychopathology literature as a reference point. The authoritative approach, influenced by the DSM, has led to several sets of criteria, which could aid clinical trials, diagnostics, and communication. However, unknown reliability and the complex relationships between empirical evidence and published criteria may limit the utility of current criteria. The empirical approach has been used to explore syndrome structures on the basis of rating scales for neuropsychiatric symptoms. The structures suggested in these studies have not been replicated easily and have been limited by either small sample sizes, restricted breadth of neuropsychiatric assessment, or both. Suggestions for further development of both approaches are offered. First, neuropsychiatric symptoms and syndromes need to be studied with measures of broad scope and in large samples. These requirements are prerequisites not only for eliciting highly informative empirical classifications but also for understanding these symptoms at a more nuanced level. Second, both approaches could benefit from more transparency. Finally, the reliability of the available authoritative criteria should be examined.

Risks and benefits of current and novel drugs to treat agitation in Alzheimer's disease

INTRODUCTION

At present, no pharmacological interventions have been approved for the treatment of agitation in Alzheimer's disease (AD), an important neuropsychiatric symptom that has been linked to increased mortality and greater caregiver burden. Antipsychotics offer some benefit, but increase the risk of adverse events such as falls, extrapyramidal symptoms, stroke, and mortality. Over the past 10 years, several new and repurposed medications have shown promise for treating AD-associated agitation.

AREAS COVERED

We review the risks and benefits of emerging therapies for agitation in AD, which include newer atypical antipsychotics, selective serotonin reuptake inhibitors, cannabinoids, and dextromethorphan combination products. Other drugs such as mirtazapine, prazosin, and lithium are also discussed. Clinicaltrials.gov, PubMed/MEDLINE, EMBASE and Cochrane Central databases were searched for relevant studies from 1 January 2012 to 1 May 2022.

EXPERT OPINION

At the present time, there are no pharmacological interventions for the treatment of agitation in AD whose benefits clearly outweigh their potential safety concerns. Therefore, management of agitation in AD should primarily be based on non-pharmacological approaches. When medications are considered necessary, they should only be initiated with the caregiver's appreciation of their risks and benefits and with careful and ongoing assessment of their safety.

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.

Plasma β-Amyloid in Mild Behavioural Impairment - Neuropsychiatric Symptoms on the Alzheimer's Continuum

INTRODUCTION

Simple markers are required to recognize older adults at higher risk for neurodegenerative disease. Mild behavioural impairment (MBI) and plasma β-amyloid (Aβ) have been independently implicated in the development of incident cognitive decline and dementia. Here we studied the associations between MBI and plasma Aβ₄₂/Aβ₄₀.

METHODS

Participants with normal cognition (n = 86) or mild cognitive impairment (n = 53) were selected from the Alzheimer's Disease Neuroimaging Initiative. MBI scores were derived from Neuropsychiatric Inventory items. Plasma Aβ₄₂/Aβ₄₀ ratios were assayed using mass spectrometry. Linear regressions were fitted to assess the association between MBI total score as well as MBI domain scores with plasma Aβ₄₂/Aβ₄₀.

RESULTS

Lower plasma Aβ₄₂/Aβ₄₀ was associated with higher MBI total score (p = 0.04) and greater affective dysregulation (p = 0.04), but not with impaired drive/motivation (p = 0.095) or impulse dyscontrol (p = 0.29) MBI domains.

CONCLUSION

In persons with normal cognition or mild cognitive impairment, MBI was associated with low plasma Aβ₄₂/Aβ₄₀. Incorporating MBI into case detection may help capture preclinical and prodromal Alzheimer's disease.

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.

Cerebrospinal Fluid Proteome Alterations Associated with Neuropsychiatric Symptoms in Cognitive Decline and Alzheimer's Disease

Although neuropsychiatric symptoms (NPS) are common and severely affect older people with cognitive decline, little is known about their underlying molecular mechanisms and relationships with Alzheimer’s disease (AD). The aim of this study was to identify and characterize cerebrospinal fluid (CSF) proteome alterations related to NPS. In a longitudinally followed-up cohort of subjects with normal cognition and patients with cognitive impairment (MCI and mild dementia) from a memory clinic setting, we quantified a panel of 790 proteins in CSF using an untargeted shotgun proteomic workflow. Regression models and pathway enrichment analysis were used to investigate protein alterations related to NPS, and to explore relationships with AD pathology and cognitive decline at follow-up visits. Regression analysis selected 27 CSF proteins associated with NPS. These associations were independent of the presence of cerebral AD pathology (defined as CSF p-tau181/Aβ1−42 > 0.0779, center cutoff). Gene ontology enrichment showed abundance alterations of proteins related to cell adhesion, immune response, and lipid metabolism, among others, in relation to NPS. Out of the selected proteins, three were associated with accelerated cognitive decline at follow-up visits after controlling for possible confounders. Specific CSF proteome alterations underlying NPS may both represent pathophysiological processes independent from AD and accelerate clinical disease progression.

Longitudinal Changes in Anger, Anxiety, and Fatigue Are Associated with Cerebrospinal Fluid Biomarkers of Alzheimer’s Disease

Alzheimer’s disease (AD) studies in cognitively normal (CN) older adults aged≥65 suggest depression is associated with molecular biomarkers (imaging and cerebrospinal fluid [CSF]). This study used linear mixed models (covariance pattern model) to assess whether baseline CSF biomarkers (Aβ 42/Aβ 40, t-Tau/Aβ 42, p-Tau/Aβ 42) predicted changes in non-depressed mood states in CN older adults (N = 248), with an average of three follow-up years. Participants with higher levels of CSF biomarkers developed more anger, anxiety, and fatigue over time compared to those with more normal levels. Non-depressed mood states in preclinical AD may be a prodrome for neuropsychiatric symptoms in symptomatic AD.

Habenula as a Neural Substrate for Aggressive Behavior

Over the past decades, an ever growing body of literature has explored the anatomy, connections, and functions of the habenula (Hb). It has been postulated that the Hb plays a central role in the control of the monoaminergic system, thus influencing a wide range of behavioral responses, and participating in the pathophysiology of a number of psychiatric disorders and neuropsychiatric symptoms, such as aggressive behaviors. Aggressive behaviors are frequently accompanied by restlessness and agitation, and are commonly observed in patients with psychiatric disorders, intellectual disabilities, and neurodegenerative diseases of aging. Recently, the Hb has been explored as a new target for neuromodulation therapies, such as deep brain stimulation, with promising results. Here we review the anatomical organization of the habenula and discuss several distinct mechanisms by which the Hb is involved in the modulation of aggressive behaviors, and propose new investigations for the development of novel treatments targeting the habenula to reduce aggressive behaviors.

Blood-based biomarkers of agitation in Alzheimer's disease: Advances and future prospects

Agitation is a common neuropsychiatric symptom that becomes more prevalent as Alzheimer's disease (AD) increases in severity. The treatment of agitation is an urgent and unmet need due to the poor outcomes associated with it, its disruptive impact on patients and caregivers, and the lack of efficacious and safe treatments. Recent research on agitation in AD with blood-based biomarkers has advanced the search for its biomarkers beyond the brain and provides new insights to understand its mechanisms and improve treatments. Here, we reviewed studies of blood-based biomarkers of agitation in AD, which show that inflammatory biomarkers are increased in patients with agitation, may predict the development of agitation, and are associated with symptom severity. In addition, they may also track symptom severity and response to treatment. Other biomarkers associated with agitation include markers of oxidative stress, brain cholesterol metabolism, motor activity, and clusterin, a chaperone protein. These results are promising and need to be replicated. Preliminary evidence suggests a role for these biomarkers in interventional studies for agitation to predict and monitor treatment response, which may eventually help enrich study samples and deliver therapy likely to benefit individual patients. Advances in blood-based biomarkers of AD including those identified in "-omic" studies and high sensitivity assays provide opportunities to identify new biomarkers of agitation. Future studies of agitation and its treatment should investigate blood-based biomarkers to yield novel insights into the neurobiological mechanisms of agitation, monitoring symptoms and response to treatment, and to identify patients likely to respond to treatments.

Post-transcriptional regulation of α7 nAChR expression by miR-98-5p modulates cognition and neuroinflammation in an animal model of Alzheimer's disease

Alzheimer's disease (AD) is a complicated neurodegenerative disease and therefore addressing multiple targets simultaneously has been believed as a promising therapeutic strategy against AD. α7 nicotinic acetylcholine receptor (nAChR), which plays an important role in improving cognitive function and alleviating neuroinflammation in central nervous system (CNS), has been regarded as a potential target in the treatment of AD. However, the regulation of α7 nAChR at post-transcriptional level in mammalian brain remains largely speculated. Herein, we uncovered a novel post-transcriptional regulatory mechanism of α7 nAChR expression in AD and further demonstrated that miR-98-5p suppressed α7 nAChR expression through directly binding to the 3'UTR of mRNA. Knockdown of miR-98-5p activated Ca²⁺ signaling pathway and consequently reversed cognitive deficits and Aβ burden in APP/PS1 mice. Furthermore, miR-98-5p downregulation increased α7 nAChR expression, and ameliorated neuroinflammation via inhibiting NF-κB pathway and upregulating Nrf2 target genes. Our findings illustrate a prominent regulatory role of miR-98-5p in targeting inflammation and cognition, and provide an insight into the potential of miR-98-5p/α7 nAChR axis as a novel therapeutic strategy for AD.

The Role of Neuropsychiatric Symptoms in Research Diagnostic Criteria for Neurodegenerative Diseases

Neuropsychiatric syndromes and symptoms play increasingly important roles in research diagnostic criteria for neurodegenerative disorders. Diagnostic criteria were reviewed including those for dementia, Alzheimer's disease, mild cognitive impairment, mild behavioral impairment, prodromal Alzheimer's disease, dementia with Lewy bodies, prodromal dementia with Lewy bodies, Parkinson's disease, multiple system atrophy, frontotemporal dementia, primary progressive aphasia, progressive supranuclear palsy, corticobasal degeneration, traumatic encephalopathy syndrome, Huntington' disease, amyotrophic lateral sclerorsis. All contemporary research diagnostic criteria for neurodegenerative disorders expect those for Parkinson's disease, primary progressive aphasia, multisystem atrophy and amyotrophic lateral sclerosis include neuropsychiatric phenomena as core diagnostic criteria. There are no disease-specific neuropsychiatric symptoms; apathy and disinhibition are common in tauopathies, and rapid-eye-movement sleep behavioral disorder occurs almost exclusively in synucleinopathies. Neuropsychiatric symptoms and syndromes are increasingly integrated into research diagnostic criteria for neurodegenerative disorders; they require clinician skills for recognition; their biology is better understood as their relationships to cognitive, motor, and autonomic symptoms of neurodegenerative disorders are studied.

Associations of AT(N) biomarkers with neuropsychiatric symptoms in preclinical Alzheimer's disease and cognitively unimpaired individuals

The development of in vivo biomarkers of Alzheimer's disease (AD) has advanced the diagnosis of AD from a clinical syndrome to a biological construct. The preclinical stage of AD continuum is defined by the identification of AD biomarkers crossing the pathological threshold in cognitively unimpaired individuals. While neuropsychiatric symptoms (NPS) are non-cognitive symptoms that are increasingly recognized as early manifestations of AD, the associations of NPS with AD pathophysiology in preclinical AD remain unclear. Here, we review the associations between NPS and AD biomarkers amyloid-β (Aβ), tau and neurodegeneration in preclinical AD and cognitively-unimpaired individuals in 19 eligible English-language publications (8 cross-sectional studies, 10 longitudinal, 1 both cross-sectional and longitudinal). The cross-sectional studies have consistently shown that NPS, particularly depressive and anxiety symptoms, are associated with higher Aβ. The longitudinal studies have suggested that greater NPS are associated with higher Aβ and cognitive decline in cognitively unimpaired subjects over time. However, most of the studies have either cross-sectionally or longitudinally shown no association between NPS and tau pathology. For the association of NPS and neurodegeneration, two studies have shown that the cerebrospinal fluid total-tau is linked to longitudinal increase in NPS and that the NPS may predict longitudinal metabolic decline in preclinical AD, respectively. However, evidence for the association between atrophy and NPS in preclinical AD is less consistent. Therefore, future longitudinal studies with well-designed methodologies and NPS measurements are required not only to determine the relationship among AT(N) biomarkers, NPS and cognitive decline, but also to elucidate the contribution of comorbid pathology to preclinical AD.

Pharmacological treatment trials of agitation in Alzheimer's disease: A systematic review of ClinicalTrials.gov registered trials

INTRODUCTION

There is increasing emphasis on the importance of optimizing and standardizing clinical trials of agitation in Alzheimer's disease (AD), but the risks of bias arising from published trials and the number and design of unpublished studies are poorly understood.

METHODS

Using the ClinicalTrials.gov database, we systematically reviewed all registered investigational clinical trials for agitation in AD to describe the landscape of agitation drug treatment trials and to assess their quality and generalizability.

RESULTS

We included 52 clinical studies registered over the past 25 years. Within published randomized controlled trials (RCTs), there was a high rate of participant dropout, poor reporting of randomization procedures, and inconsistent definitions of the sample included for analysis. There was also evidence of publication and funder bias.

DISCUSSION

We discuss factors that limit the internal and external validity of published RCTs and make additional recommendations for the conduct and reporting of future clinical trials of agitation in AD.

Associations of C-Reactive Protein, Free Triiodothyronine, Thyroid Stimulating Hormone and Creatinine Levels with Agitation in Patients with Schizophrenia: A Comparative Cross-Sectional Study

PURPOSE

Agitation is prevalent among inpatients with schizophrenia. The aim of this study was to investigate whether biochemical parameters are associated with agitation in schizophrenia.

PATIENTS AND METHODS

Agitation was evaluated by the Positive and Negative Syndrome Scale-Excited Component questionnaire (PANSS-EC). Fasting serum levels of C-reactive protein (CRP), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), uric acid (UA), creatinine, glucose and lipids were measured.

RESULTS

The analysis included 154 inpatients with schizophrenia (71 with agitation, 83 without agitation) and 75 healthy control subjects. Patients with schizophrenia and agitation had higher serum levels of CRP, FT3, FT4 and UA as well as lower levels of serum TSH and creatinine than patients without agitation (all P < 0.05). Multivariate logistic regression analysis indicated that serum CRP (odds ratio [OR] = 1.470, P = 0.001), FT3 (OR = 13.026, P < 0.001), TSH (OR = 0.758, P = 0.033) and creatinine (OR = 0.965, P = 0.004) were significantly associated with agitation in schizophrenia. CRP, FT3, TSH and creatinine achieved an area under the ROC curve of 0.626, 0.728, 0.620 and 0.663 respectively in discriminating schizophrenia with or without agitation.

CONCLUSION

Increased serum CRP and FT3 levels and decreased serum TSH and creatinine levels are independent risk factors for agitation in hospitalized patients with schizophrenia. Inflammation, thyroid hormones and renal function may be involved in the pathogenesis of agitation in schizophrenia.

Strength training or green tea prevent memory deficits in a β-amyloid peptide-mediated Alzheimer's disease model

Antioxidant supplementation and physical exercise have been discussed as strategies to minimize neurodegeneration in Alzheimer's disease (AD). We investigated the neuroprotective effects of strength exercise (StrEx) and green tea (GT) supplementation, combined or not, on memory impairments induced by β-amyloid characterizing an AD-like condition in rats. Wistar rats were submitted to 8 weeks of StrEx, GT supplementation, or StrEx and GT combined. AD-like condition was induced by injection of Aβ (25-35) in the hippocampus. We evaluate object recognition (OR) and social recognition (SR) memory, and removed the rats' hippocampus for biochemical analysis. StrEx improved OR and SR. StrEx combined with GT improved OR and did not improve SR. GT reduced antioxidant capacity and improved acetylcholinesterase activity. Both strength exercise and green tea are neuroprotective against impairments resultant of β-amyloid, but benefits do not add up when the two interventions are associated.

24S-Hydroxycholesterol Is Associated with Agitation Severity in Patients with Moderate-to-Severe Alzheimer's Disease: Analyses from a Clinical Trial with Nabilone

Background:

Agitation is a prevalent and difficult-to-treat symptom of Alzheimer’s disease (AD). The endocannabinoid system (ECS) has been a target of interest for the treatment of agitation. However, ECS signaling may interact with AD-related changes in brain cholesterol metabolism. Elevated brain cholesterol, reflected by reduced serum 24-S-hydroxycholesterol (24S-OHC), is associated with reduced membrane fluidity, preventing ligand binding to cannabinoid receptor 1.

Objective:

To assess whether 24S-OHC was associated with agitation severity and response to nabilone.

Methods:

24S-OHC was collected from AD patients enrolled in a clinical trial on nabilone at the start and end of each phase. This allowed for the cross-sectional and longitudinal investigation between 24S-OHC and agitation (Cohen Mansfield Agitation Inventory, CMAI). Post-hoc analyses included adjustments for baseline standardized Mini-Mental Status Exam (sMMSE), and analyses with CMAI subtotals consistent with the International Psychogeriatric Association (IPA) definition for agitation (physical aggression and nonaggression, and verbal aggression).

Results:

24S-OHC was not associated with CMAI scores cross-sectionally or longitudinally, before and after adjusting for baseline sMMSE. However, 24S-OHC was associated with greater CMAI IPA scores at baseline (F(1,36) = 4.95, p = 0.03). In the placebo phase only, lower 24S-OHC at baseline was associated with increases in CMAI IPA scores (b = –35.2, 95% CI –65.6 to –5.0, p = 0.02), and decreases in 24S-OHC were associated with increases in CMAI IPA scores (b = –20.94, 95% CI –57.9 to –4.01, p = 0.03).

Conclusion:

24S-OHC was associated with agitation severity cross-sectionally, and longitudinally in patients with AD. However, 24S-OHC did not predict treatment response, and does not change over time with nabilone.

Agitation and impulsivity in mid and late life as possible risk markers for incident dementia

To identify knowledge gaps regarding new-onset agitation and impulsivity prior to onset of cognitive impairment or dementia the International Society to Advance Alzheimer's Research and Treatment Neuropsychiatric Syndromes (NPS) Professional Interest Area conducted a scoping review. Extending a series of reviews exploring the pre-dementia risk syndrome Mild Behavioral Impairment (MBI), we focused on late-onset agitation and impulsivity (the MBI impulse dyscontrol domain) and risk of incident cognitive decline and dementia. This scoping review of agitation and impulsivity pre-dementia syndromes summarizes the current biomedical literature in terms of epidemiology, diagnosis and measurement, neurobiology, neuroimaging, biomarkers, course and prognosis, treatment, and ongoing clinical trials. Validations for pre-dementia scales such as the MBI Checklist, and incorporation into longitudinal and intervention trials, are needed to better understand impulse dyscontrol as a risk factor for mild cognitive impairment and dementia.

Sensing a problem: Proof of concept for characterizing and predicting agitation

INTRODUCTION

Agitation, experienced by patients with dementia, is difficult to manage and stressful for caregivers. Currently, agitation is primarily assessed by caregivers or clinicians based on self-report or very brief periods of observation. This limits availability of comprehensive or sensitive enough reporting to detect early signs of agitation or identify its precipitants. The purpose of this article is to provide proof of concept for characterizing and predicting agitation using a system that continuously monitors patients' activities and living environment within memory care facilities.

METHODS

Continuous and unobtrusive monitoring of a participant is achieved using behavioral sensors, which include passive infrared motion sensors, door contact sensors, a wearable actigraphy device, and a bed pressure mat sensor installed in the living quarters of the participant. Environmental sensors are also used to continuously assess temperature, light, sound, and humidity. Episodes of agitation are reported by nursing staff. Data collected for 138 days were divided by 8-hour nursing shifts. Features from agitated shifts were compared to those from non-agitated shifts using t-tests.

RESULTS

A total of 37 episodes of agitation were reported for a male participant, aged 64 with Alzheimer's disease, living in a memory care unit. Participant activity metrics (eg, transitions within the living room, sleep scores from the bedmat, and total activity counts from the actigraph) significantly correlated with occurrences of agitation at night (P < 0.05). Environmental variables (eg, humidity) also correlated with the occurrences of agitation at night (P < 0.05). Higher activity levels were also observed in the evenings before agitated nights.

DISCUSSION

A platform of sensors used for unobtrusive and continuous monitoring of participants with dementia and their living space seems feasible and shows promise for characterization of episodes of agitation and identification of behavioral and environmental precipitants of agitation.

Behavioral and Psychological Symptoms of Dementia (BPSD): Clinical Characterization and Genetic Correlates in an Italian Alzheimer's Disease Cohort

BACKGROUND

The occurrence of Behavioral and Psychological Symptoms of Dementia (BPSD) in Alzheimer's Disease (AD) patients hampers the clinical management and exacerbates the burden for caregivers. The definition of the clinical distribution of BPSD symptoms, and the extent to which symptoms are genetically determined, are still open to debate. Moreover, genetic factors that underline BPSD symptoms still need to be identified.

PURPOSE

To characterize our Italian AD cohort according to specific BPSD symptoms as well as to endophenotypes. To evaluate the associations between the considered BPSD traits and COMT, MTHFR, and APOE genetic variants.

METHODS

AD patients (n = 362) underwent neuropsychological examination and genotyping. BPSD were assessed with the Neuropsychiatric Inventory scale.

RESULTS

APOE and MTHFR variants were significantly associated with specific single BPSD symptoms. Furthermore, "Psychosis" and "Hyperactivity" resulted in the most severe endophenotypes, with APOE and MTHFR implicated as both single risk factors and "genexgene" interactions.

CONCLUSIONS

We strongly suggest the combined use of both BPSD single symptoms/endophenotypes and the "genexgene" interactions as valid strategies for expanding the knowledge about the BPSD aetiopathogenetic mechanisms.

Agitation, Oxidative Stress, and Cytokines in Alzheimer Disease: Biomarker Analyses From a Clinical Trial With Nabilone for Agitation

The endocannabinoid system has been a target of interest for agitation in Alzheimer disease (AD) because of potential behavioral effects and its potential impact on mechanisms implicated in AD such as oxidative stress (OS) and neuroinflammation. We explored whether serum markers of OS and neuroinflammation were associated with response to the cannabinoid nabilone in agitated patients with AD (N = 38). All participants were enrolled in a 14-week, double-blind, cross-over trial comparing nabilone to placebo (6 weeks each) with a 1-week washout between phases. Samples were collected at the start and end of each phase. The cross-sectional relationship agitation (Cohen Mansfield Agitation Inventory) and OS and inflammatory markers were investigated to select markers of interest. Significant markers were then explored for their relationship with response. The OS marker, 4-hydroxynonenal (4-HNE; F_{1, 35} = 6.41, P = .016), and the proinflammatory cytokine, tumor necrosis factor-α (TNF-α; F_{1, 29} = 3.97, P = .06), were associated with agitation severity, and TNF-α remained significantly associated (F_{2, 25} = 3.69, P = .04) after adjustment for cognition. In the placebo phase, lower baseline 4-HNE was associated with decreases in agitation severity only (b = 0.01, P = .01), while lower baseline TNF-α was associated with decreases in agitation severity in the nabilone phase only (b = 1.14, P = .045). Changes in 4-HNE were not associated with changes in agitation severity in either phase. In the nabilone phase, lower baseline TNF-α was associated with decreases in agitation severity (b = 1.14, P = .045), and decreases in TNF-α were associated with decreases in agitation severity (b = 1.12, P = .006). These findings suggest that OS and neuroinflammation may be associated with agitation severity, while nabilone may have anti-inflammatory effects.

Analysis of Whole-Exome Sequencing Data for Alzheimer Disease Stratified by APOE Genotype

IMPORTANCE

Previous genome-wide association studies of common variants identified associations for Alzheimer disease (AD) loci evident only among individuals with particular APOE alleles.

OBJECTIVE

To identify APOE genotype-dependent associations with infrequent and rare variants using whole-exome sequencing.

DESIGN, SETTING, AND PARTICIPANTS

The discovery stage included 10 441 non-Hispanic white participants in the Alzheimer Disease Sequencing Project. Replication was sought in 2 independent, whole-exome sequencing data sets (1766 patients with AD, 2906 without AD [controls]) and a chip-based genotype imputation data set (8728 patients with AD, 9808 controls). Bioinformatics and functional analyses were conducted using clinical, cognitive, neuropathologic, whole-exome sequencing, and gene expression data obtained from a longitudinal cohort sample including 402 patients with AD and 647 controls. Data were analyzed between March 2017 and September 2018.

MAIN OUTCOMES AND MEASURES

Score, Firth, and sequence kernel association tests were used to test the association of AD risk with individual variants and genes in subgroups of APOE ε4 carriers and noncarriers. Results with P ≤ 1 × 10-5 were further evaluated in the replication data sets and combined by meta-analysis.

RESULTS

Among 3145 patients with AD and 4213 controls lacking ε4 (mean [SD] age, 83.4 [7.6] years; 4363 [59.3.%] women), novel genome-wide significant associations were obtained in the discovery sample with rs536940594 in AC099552 (odds ratio [OR], 88.0; 95% CI, 9.08-852.0; P = 2.22 × 10-7) and rs138412600 in GPAA1 (OR, 1.78; 95% CI, 1.44-2.2; meta-P = 7.81 × 10-8). GPAA1 was also associated with expression in the brain of GPAA1 (β = -0.08; P = .03) and its repressive transcription factor, FOXG1 (β = 0.13; P = .003), and global cognition function (β = -0.53; P = .009). Significant gene-wide associations (threshold P ≤ 6.35 × 10-7) were observed for OR8G5 (P = 4.67 × 10-7), IGHV3-7 (P = 9.75 × 10-16), and SLC24A3 (P = 2.67 × 10-12) in 2377 patients with AD and 706 controls with ε4 (mean [SD] age, 75.2 [9.6] years; 1668 [54.1%] women).

CONCLUSIONS AND RELEVANCE

The study identified multiple possible novel associations for AD with individual and aggregated rare variants in groups of individuals with and without APOE ε4 alleles that reinforce known and suggest additional pathways leading to AD.

Enhancing face validity of mouse models of Alzheimer's disease with natural genetic variation

Classical laboratory strains show limited genetic diversity and do not harness natural genetic variation. Mouse models relevant to Alzheimer's disease (AD) have largely been developed using these classical laboratory strains, such as C57BL/6J (B6), and this has likely contributed to the failure of translation of findings from mice to the clinic. Therefore, here we test the potential for natural genetic variation to enhance the translatability of AD mouse models. Two widely used AD-relevant transgenes, APPswe and PS1de9 (APP/PS1), were backcrossed from B6 to three wild-derived strains CAST/EiJ, WSB/EiJ, PWK/PhJ, representative of three Mus musculus subspecies. These new AD strains were characterized using metabolic, functional, neuropathological and transcriptional assays. Strain-, sex- and genotype-specific differences were observed in cognitive ability, neurodegeneration, plaque load, cerebrovascular health and cerebral amyloid angiopathy. Analyses of brain transcriptional data showed strain was the greatest driver of variation. We identified significant variation in myeloid cell numbers in wild type mice of different strains as well as significant differences in plaque-associated myeloid responses in APP/PS1 mice between the strains. Collectively, these data support the use of wild-derived strains to better model the complexity of human AD.