Neuroimaging correlates of neuropsychiatric symptoms in Alzheimer's disease: a review of 20 years of research

Exploring the Neural Mechanisms of Mirrored-Self Misidentification in Alzheimer's Disease

OBJECTIVE

Alzheimer's disease (AD) is a complex neurodegenerative condition that causes a range of cognitive disturbances, including mirror-self misidentification syndrome (MSM), in which patients cannot recognize themselves in a mirror. However, the mechanism of action of MSM is not precisely known. This study aimed to explore the possible neural mechanisms of action of MSM in AD using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI).

METHODS

This study included 48 AD patients, 13 in the MSM group and 35 in the non-MSM group. The permeability of the blood-brain barrier (BBB) was quantitatively monitored by measuring the transfer rate (Ktrans) of the contrast agent from the vasculature to the surrounding tissue using DCE-MRI. The concentration of contrast agents in different brain regions was measured, and the Patlak model was used to calculate Ktrans. Ktrans values were compared between the left and right cerebral hemispheres in different brain areas between the MSM and non-MSM groups. Additionally, the difference in Ktrans values between mild and severe MSM was assessed. Logistic regression analysis was used to examine the risk factors for MSM.

RESULTS

The Mann‒Whitney U test was used to compare two groups and revealed elevated Ktrans values in the left thalamus, left putamen, left globus pallidus, left corona radiata, and right caudate in the MSM group (p < 0.05). Logistic regression analysis revealed that increased Ktrans values in the left putamen (OR = 1.53, 95% CI = 1.04, 2.26) and left globus pallidus (OR = 1.54, 95% CI = 1.02, 2.31) may be risk factors for MSM. After dividing MSM patients into mild and moderate-severe groups, the Ktrans values of the thalamus in the moderate-severe group were greater than those in the mild group (p < 0.05).

CONCLUSION

Our study revealed the relationship between BBB permeability and MSM in AD. MSM is associated with BBB breakdown in the left putamen and globus pallidus. The left putamen and globus pallidus may function in mirror self-recognition. Higher BBB permeability in the thalamus may reflect the severity of AD in MSM.

Neuroanatomical correlates and predictors of psychotic symptoms in Alzheimer's disease: a systematic review and meta-analysis

BACKGROUND

Psychotic symptoms (hallucinations and delusions) are a type of neuropsychiatric symptom found during Alzheimer's Disease (AD).

OBJECTIVE

This systematic review aims to comprehensively capture, analyse, and evaluate the body of evidence that has investigated associations between brain regions/networks and psychotic symptoms in AD.

METHODS

The protocol, created according to the PRISMA guidelines, was pre-registered on OSF (https://osf.io/tg8xp/). Searches were performed using PubMed, Web of Science and PsycInfo. A partial coordinate-based meta-analysis (CBMA) was performed based on data availability.

RESULTS

Eighty-two papers were selected: delusions were found to be associated mainly with right fronto-temporal brain regions and the insula; hallucinations mainly with fronto-occipital areas; both were frequently associated with the anterior cingulate cortex. The CBMA, performed on the findings of fourteen papers on delusions, identified a cluster in the frontal lobe, one in the putamen, and a smaller one in the insula.

CONCLUSIONS

The available evidence highlights that key brain regions, predominantly in the right frontal lobe, the anterior cingulate cortex, and temporo-occipital areas, appear to underpin the different manifestations of psychotic symptoms in AD and MCI. The fronto-temporal areas identified in relation to delusions may underpin a failure to assimilate correct information and consider alternative possibilities (which might generate and maintain the delusional belief), and dysfunction within the salience network (anterior cingulate cortex and insula) may suggest a contribution for how internal and external stimuli are identified; the fronto-occipital areas linked to hallucinations may indicate diminished sensory processing and non-optimal predictive processing, that together contribute to misinterpretation of stimuli and misperceptions; the fronto-temporal and occipital areas, as well as the anterior cingulate cortex were linked to the psychotic cluster.

Default mode network dynamics: An integrated neurocircuitry perspective on social dysfunction in human brain disorders

Our intricate social brain is implicated in a range of brain disorders, where social dysfunction emerges as a common neuropsychiatric feature cutting across diagnostic boundaries. Understanding the neurocircuitry underlying social dysfunction and exploring avenues for its restoration could present a transformative and transdiagnostic approach to overcoming therapeutic challenges in these disorders. The brain's default mode network (DMN) plays a crucial role in social functioning and is implicated in various neuropsychiatric conditions. By thoroughly examining the current understanding of DMN functionality, we propose that the DMN integrates diverse social processes, and disruptions in brain communication at regional and network levels due to disease hinder the seamless integration of these social functionalities. Consequently, this leads to an altered balance between self-referential and attentional processes, alongside a compromised ability to adapt to social contexts and anticipate future social interactions. Looking ahead, we explore how adopting an integrated neurocircuitry perspective on social dysfunction could pave the way for innovative therapeutic approaches to address brain disorders.

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

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

Role of fronto-limbic circuit in neuropsychiatric symptoms of dementia: clinical evidence from an exploratory study

Background

Neuropsychiatric symptoms (NPSs) are a distressful aspect of dementia and the knowledge of structural correlates of NPSs is limited. We aimed to identify associations of fronto-limbic circuit with specific NPSs in patients with various types of cognitive impairment.

Methods

Of 84 participants, 27 were diagnosed with mild cognitive impairment (MCI), 41 with Alzheimer's disease (AD) dementia and 16 with non-AD dementia. In all patients we assessed regional brain morphometry using a region of interest (ROI)-based analysis. The mean cortical thickness (CT) of 20 cortical regions and the volume (V) of 4 subcortical areas of the fronto-limbic system were extracted. NPSs were rated with the Neuropsychiatric Inventory (NPI). We used multiple linear regression models adjusted for age and disease duration to identify significant associations between scores of NPI sub-domains and MRI measures of brain morphometry.

Results

All significant associations found were negative, except those between irritability and the fronto-opercular regions in MCI patients (corresponding to a 40-50% increase in CT) and between delusions and hippocampus and anterior cingulate gyrus (with a 40-60% increase). Apathy showed predominant involvement of the inferior frontal regions in AD group (a 30% decrease in CT) and of the cingulate cortex in non-AD group (a 50-60% decrease in CT). Anxiety correlated in MCI patients with the cingulate gyrus and caudate, with a CT and V decrease of about 40%, while hallucinations were associated with left enthorinal gyrus and right amygdala and temporal pole. Agitation showed associations in the AD group with the frontal regions and the temporal pole, corresponding to a 30-40% decrease in CT. Euphoria, disinhibition and eating abnormalities were associated in the MCI group with the entorhinal, para-hippocampal and fusiform gyri, the temporal pole and the amygdala (with a 40-70% decrease in CT and V). Finally, aberrant motor behavior reported a significant association with frontal and cingulate regions with a 50% decrease in CT.

Conclusion

Our findings indicate that specific NPSs are associated with the structural involvement of the fronto-limbic circuit across different types of neurocognitive disorders. Factors, such as age and disease duration, can partly account for the variability of the associations observed.

The association of GNB5 with Alzheimer disease revealed by genomic analysis restricted to variants impacting gene function

Disease-associated variants identified from genome-wide association studies (GWASs) frequently map to non-coding areas of the genome such as introns and intergenic regions. An exclusive reliance on gene-agnostic methods of genomic investigation could limit the identification of relevant genes associated with polygenic diseases such as Alzheimer disease (AD). To overcome such potential restriction, we developed a gene-constrained analytical method that considers only moderate- and high-risk variants that affect gene coding sequences. We report here the application of this approach to publicly available datasets containing 181,388 individuals without and with AD and the resulting identification of 660 genes potentially linked to the higher AD prevalence among Africans/African Americans. By integration with transcriptome analysis of 23 brain regions from 2,728 AD case-control samples, we concentrated on nine genes that potentially enhance the risk of AD: AACS, GNB5, GNS, HIPK3, MED13, SHC2, SLC22A5, VPS35, and ZNF398. GNB5, the fifth member of the heterotrimeric G protein beta family encoding Gβ5, is primarily expressed in neurons and is essential for normal neuronal development in mouse brain. Homozygous or compound heterozygous loss of function of GNB5 in humans has previously been associated with a syndrome of developmental delay, cognitive impairment, and cardiac arrhythmia. In validation experiments, we confirmed that Gnb5 heterozygosity enhanced the formation of both amyloid plaques and neurofibrillary tangles in the brains of AD model mice. These results suggest that gene-constrained analysis can complement the power of GWASs in the identification of AD-associated genes and may be more broadly applicable to other polygenic diseases.

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.

Depression and Agitation Factors Are Related to Regional Brain Atrophy and Faster Longitudinal Cognitive Decline in Mild Cognitive Impairment

BACKGROUND

Neuropsychiatric symptoms (NPS) are a common aspect of Alzheimer's disease (AD). Multiple studies have investigated its brain correlates, but it still remains unclear how they relate with brain atrophy in mild cognitive impairment (MCI).

OBJECTIVE

Our objective was to investigate brain volume in MCI patients as a function of NPS.

METHODS

We measured grey matter volume, neuropsychological status and NPS (Neuropsychiatric Inventory, NPI), in a sample of 81 MCI patients (43 females). Participants were divided in groups depending on presence (NPS+) or absence (NPS-) of NPS and on type of NPS.

RESULTS

We found lower volume of left temporal pole in patients with depression compared to NPS- (p = 0.012), and in patients with agitation compared to NPS- in the right middle occipital gyrus (p = 0.003). We also found a significant correlation between volume of left temporal pole and MMSE (r (78)  = 0.232, p = 0.019). Finally, NPS+ presented lower cross-sectional cognitive level than NPS- (t (79)  = 1.79, p = 0.038), and faster cognitive decline (t (48)  = -1.74, p = 0.044).

CONCLUSIONS

Our results support the colocalization of structural damage as a possible mechanism underlying the relationship between MCI and depression and provide novel evidence regarding agitation. Moreover, our longitudinal evidence highlights the relevance of an adequate identification of NPS in MCI patients to identify those at risk of faster cognitive decline.

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.

Correlation Between the Fractional Amplitude of Low-Frequency Fluctuation and Cognitive Defects in Alzheimer's Disease

Background

The fractional amplitude of low-frequency fluctuations (fALFFs) can detect spontaneous brain activity. However, the association between abnormal brain activity and cognitive function, amyloid protein (Aβ), and emotion in Alzheimer's disease (AD) patients remains unclear.

Objective

This study aimed to survey alterations in fALFF in different frequency bands and the relationship between abnormal brain activity, depressive mood, and cognitive function to determine the potential mechanism of AD.

Methods

We enrolled 34 AD patients and 32 healthy controls (HC). All the participants underwent resting-state magnetic resonance imaging, and slow-4 and slow-5 fALFF values were measured. Subsequently, the study determined the correlation of abnormal brain activity with mood and cognitive function scores.

Results

AD patients revealed altered mfALFF values in the slow-5 and slow-4 bands. In the slow-4 band, the altered mfALFF regions were the right cerebellar crus I, right inferior frontal orbital gyrus (IFOG), right supramarginal gyrus, right precuneus, angular gyrus, and left middle cingulate gyrus. Elevated mfALFF values in the right IFOG were negatively associated with Montreal Cognitive Assessment scores, Boston Naming Test, and Aβ1-42 levels. The mfALFF value of the AD group was lower than the HC group in the slow-5 band, primarily within the right inferior parietal lobule and right precuneus.

Conclusions

Altered mfALFF values in AD patients are linked with cognitive dysfunction. Compared with HCs, Aβ1-42 levels in AD patients are related to abnormal IFOG activity. Therefore, mfALFF could be a potential biomarker of AD.

Correlation between white matter hyperintensity and delusional symptoms in Alzheimer's disease

BACKGROUND

Patients with Alzheimer's disease (AD) often exhibit neuropsychiatric symptoms (NPS), particularly delusions. Previous studies have shown an association between white matter hyperintensities (WMH) and specific NPS. This study aims to explore the relationship between WMH volume and delusions in AD patients by comparing the WMH volumes of delusional and non-delusional subgroups.

METHODS

80 AD patients were divided into a delusion group (n = 36) and a non-delusion group (n = 44) based on the Neuropsychiatric Inventory (NPI). The brain cortical volume and WMH volume were quantitatively calculated for all 80 patients, including total WMH volume, periventricular WMH (PVWMH) volume, deep WMH volume, as well as bilateral frontal lobe, temporal lobe, parietal lobe, and occipital lobe WMH volumes. Firstly, we compared the differences in WMH volumes between the delusion group and non-delusion group. Then, within the delusion group, we further categorized patients based on severity scores of their delusional symptoms into mild (1 point), moderate (2 points), or severe groups (3 points). We compared the WMH volumes among these three groups to investigate the role of WMH volume in delusional symptoms.

RESULTS

There was a significant difference in left occipital lobe WMH volume between the delusion group and non-delusion group(P < 0.05). Within the delusion group itself, there were significant differences in overall WMH volume as well as PVWMH volume among patients with mild or severe levels of delusions(P < 0.05).

CONCLUSION

Left occipital lobe WMH volume may be associated with the occurrence of delusional AD patients, and the total volume of whole-brain WMH and PVWMH volume may affect the degree of severity of delusional symptoms.

Comorbid amyloid with cerebrovascular disease in domain-specific cognitive and neuropsychiatric disturbances: a cross-sectional memory clinic study

Dementia is a multifactorial disorder that is likely influenced by both Alzheimer's disease (AD) and vascular pathologies. We evaluated domain-specific cognitive and neuropsychiatric dysfunction using a two-neuroimaging biomarker construct (beta-amyloid [Aβ] and cerebrovascular disease [CeVD]). We analyzed data from 216 memory clinic participants (mean age = 75.9 ± 6.9; 56.5% female) with neuropsychological and neuropsychiatric assessments, 3T-MRI, and Aβ-PET imaging. Structural equation modeling showed that the largest Aβ (A+) effect was on memory (B = -1.50) and apathy (B = 0.26), whereas CeVD effects were largest on language (B = -1.62) and hyperactivity (B = 0.32). Group comparisons showed that the A+C+ group had greater memory impairment (B = -1.55), hyperactivity (B = 0.79), and apathy (B = 0.74) compared to A-C+; and greater language impairment (B = -1.26) compared to A+C-. These potentially additive effects of Aβ and CeVD burden underline the importance of early detection and treatment of Aβ alongside optimal control of vascular risk factors as a potential strategy in preventing cognitive and neurobehavioral impairment.

Neuropsychiatric symptoms and their neural correlates in individuals with mild cognitive impairment

OBJECTIVES

Neuropsychiatric symptoms are common in subjects with MCI and associated with higher risk of progression to AD. The cognitive and neuroanatomical correlates of neuropsychiatric symptoms in MCI have not been fully elucidated. In this study, we sought to evaluate the association between neuropsychiatric symptoms, cognitive function, regional tau deposition, and brain volumes in MCI subjects.

METHODS

A total of 233 MCI and 305 healthy comparisons were selected from the ADNI-3 cohort. All the subjects underwent a comprehensive neuropsychological assessment, volumetric MR brain scan, and Flortaucipir PET for in vivo assessment of regional tau deposition. Prevalence of neuropsychiatric symptoms was evaluated by means of the NPI questionnaire. Multivariate analyses of variance were used to detect differences in cognitive and imaging markers in MCI subjects with and without neuropsychiatric symptoms.

RESULTS

61.4% MCI subjects showed at least one neuropsychiatric symptom, with the most prevalent ones being depression (26.1%), irritability (23.6%), and sleep disturbances (23.6%). There was a significant effect of neuropsychiatric symptoms on cognitive tests of frontal and executive functions. MCI subjects with neuropsychiatric symptoms showed reduced brain volumes in the orbitofrontal and posterior cingulate cortices, while no effects were detected on regional tau deposition. Posterior cingulate cortex volume was the only predictor of global neuropsychiatric burden in this MCI population.

CONCLUSIONS

Neuropsychiatric symptoms occur early in the AD trajectory and are mainly related to defects of control executive abilities and to the reduction of gray matter volume in the orbitofrontal and posterior cingulate cortices. A better understanding of the cognitive and neuroanatomical mechanisms of neuropsychiatric symptoms in MCI could help develop more targeted and efficacious treatment alternatives.

Associations between neuropsychiatric symptoms of affective and vegetative domains and brain morphology in aging people with mild cognitive impairment and Alzheimer's disease

OBJECTIVE

Neuropsychiatric symptoms (NPS) are common in mild cognitive impairment (MCI) and even more in Alzheimer's disease (AD). The symptom-based cluster including nighttime disturbances, depression, appetite changes, anxiety, and apathy (affective and vegetative symptoms) was associated with an increased risk of dementia in MCI and has common neuroanatomical associations. Our objective was to investigate the differences in brain morphology associations with affective and vegetative symptoms between three groups: cognitively normal older adults (CN), MCI and AD.

MATERIAL AND METHODS

Alzheimer's Disease Neuroimaging Initiative data of 223 CN, 367 MCI and 175 AD, including cortical volumes, surface areas and thicknesses and severity scores of the five NPS were analyzed. A whole-brain vertex-wise general linear model was performed to test for intergroup differences (CN-MCI, CN-AD, AD-MCI) in brain morphology associations with five NPS. Multiple regressions were conducted to investigate cortical change as a function of NPS severity in the AD-MCI contrast.

RESULTS

We found (1) signature differences in nighttime disturbances associations with prefrontal regions in AD-MCI, (2) signature differences in NPS associations with temporal regions in AD-MCI for depression and in CN-AD for anxiety, (3) decreased temporal metrics in MCI as nighttime disturbances and depression severity increased, (4) decreased pars triangularis metrics in AD as nighttime disturbances and apathy severity increased.

CONCLUSION

Each NPS seems to have a signature on brain morphology. Affective and vegetative NPS were primarily associated with prefrontal and temporal regions. These signatures open the possibility of potential future assessments of links between brain morphology and NPS on an individual level.

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.

Distinguishing apathy from depression: A review differentiating the behavioral, neuroanatomic, and treatment-related aspects of apathy from depression in neurocognitive disorders

OBJECTIVES

This narrative review describes the clinical features of apathy and depression in individuals with neurocognitive disorders (NCDs), with the goal of differentiating the two syndromes on the basis of clinical presentation, diagnostic criteria, neuropathological features, and contrasting responses to treatments.

METHODS

Literature was identified using PubMed, with search terms to capture medical conditions of interest; additional references were also included based on our collective experience and knowledge of the literature.

RESULTS

Evidence from current literature supports the distinction between the two disorders; apathy and depression occur with varying prevalence in individuals with NCDs, pose different risks of progression to dementia, and have distinct, if overlapping, neurobiological underpinnings. Although apathy is a distinct neuropsychiatric syndrome, distinguishing apathy from depression can be challenging, as both conditions may occur concurrently and share several overlapping features. Apathy is associated with unfavorable outcomes, especially those with neurodegenerative etiologies (e.g., Alzheimer's disease) and is associated with an increased burden for both patients and caregivers. Diagnosing apathy is important not only to serve as the basis for appropriate treatment, but also for the development of novel targeted interventions for this condition. Although there are currently no approved pharmacologic treatments for apathy, the research described in this review supports apathy as a distinct neuropsychiatric condition that warrants specific treatments aimed at alleviating patient disability.

CONCLUSIONS

Despite differences between these disorders, both apathy and depression pose significant challenges to patients, their families, and caregivers; better diagnostics are needed to develop more tailored treatment and support.

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.

Spatiotemporal Characteristics of Regional Brain Perfusion Associated with Neuropsychiatric Symptoms in Patients with Alzheimer's Disease

BACKGROUND

Current technology for exploring neuroimaging markers and neural circuits of neuropsychiatric symptoms (NPS) in patients with Alzheimer's disease (AD) is expensive and usually invasive, limiting its use in clinical practice.

OBJECTIVE

To investigate the cerebral morphology and perfusion characteristics of NPS and identify the spatiotemporal perfusion circuits of NPS sub-symptoms.

METHODS

This nested case-control study included 102 AD patients with NPS and 51 age- and sex-matched AD patients without NPS. Gray matter volume, cerebral blood flow (CBF), and arterial transit time (ATT) were measured and generated using time-encoded 7-delay pseudo-continuous arterial spin labeling (pCASL). Multiple conditional logistic regression analysis was used to identify neuroimaging markers of NPS. The associations between the CBF or ATT of affected brain areas and NPS sub-symptoms were evaluated after adjusting for confounding factors. The neural circuits of sub-symptoms were identified based on spatiotemporal perfusion sequencing.

RESULTS

Lower Mini-Mental State Examination scores (p < 0.001), higher Caregiver Burden Inventory scores (p < 0.001), and higher CBF (p = 0.001) and ATT values (p < 0.003) of the right anteroventral thalamic nucleus (ATN) were risk factors for NPS in patients with AD. Six spatiotemporal perfusion circuits were found from 12 sub-symptoms, including the anterior cingulate gyri-temporal pole/subcortical thalamus-cerebellum circuit, insula-limbic-cortex circuit, subcortical thalamus-temporal pole-cortex circuit, subcortical thalamus-cerebellum circuit, frontal cortex-cerebellum-occipital cortex circuit, and subcortical thalamus-hippocampus-dorsal raphe nucleus circuit.

CONCLUSIONS

Prolonged ATT and increased CBF of the right ATN may be neuroimaging markers for detecting NPS in patients with AD. Time-encoded pCASL could be a reliable technique to explore the neural perfusional circuits of NPS.

Accelerated atrophy in dopaminergic targets and medial temporo-parietal regions precedes the onset of delusions in patients with Alzheimer's disease

People with Alzheimer's disease (AD) and delusions have worse quality of life and prognosis. However, early markers of delusions have not been identified yet. The present study investigated whether there are any detectable differences in grey matter (GM) volume and cognitive changes in the year before symptom onset between patients with AD who did and did not develop delusions. Two matched samples of AD patients, 63 who did (PT-D) and 63 who did not develop delusions (PT-ND) over 1 year, were identified from the Alzheimer's Disease Neuroimaging Initiative database. The Neuropsychiatric Inventory (NPI) was used to assess the presence of delusions. Sixty-three additional matched healthy controls (HC) were selected. Repeated-measures ANCOVA models were used to investigate group-by-time effects on the volume of selected GM regions of interest and on cognitive performance. No neurocognitive differences were observed between patient groups prior to symptom onset. Greater episodic memory decline and GM loss in bilateral caudate nuclei, medio-temporal and midline cingulo-parietal regions were found in the PT-D compared with the PT-ND group. A pattern of faster GM loss in brain areas typically affected by AD and in cortical and subcortical targets of dopaminergic pathways, paralleled by worsening of episodic memory and behavioural symptoms, may explain the emergence of delusions in patients with AD.

Neuropsychiatric symptoms in patients with possible vascular cognitive impairment, does sex matter?

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Manifestations of neuropsychiatric symptoms in patients with VCI differ by sex.

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In women the presence of apathy was associated with higher risk of clinical progression.

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In men depression and aberrant motor behavior were associated with higher risk of progression.

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Management strategies of NPS could benefit from sex-specific approaches.

Background

Neuropsychiatric symptoms (NPS) are common in patients with vascular cognitive impairment (VCI). We aimed to establish sex differences in the manifestation of NPS in memory clinic patients with possible VCI and identify which NPS are determinants of clinical progression in women and men separately.

Methods

We included 718 memory clinic patients (age 68 ± 8; 45% women) with cognitive complaints and vascular brain lesions on MRI (i.e. possible VCI). NPS were measured using the 12-item Neuropsychiatric Inventory. Clinical progression after two years (women 18%, men 14%) was defined as increase in CDR ≥1 or institutionalization (available n = 589 without advanced dementia at baseline). The association between NPS and clinical progression was assessed with Cox proportional hazard models stratified by sex, adjusted for age and clinical diagnosis and in a second model additionally for manifestations of vascular brain lesions.

Results

Men more often presented with agitation (29% versus 17%, p<.05) and irritability (58% versus 45%, p<.05), the other 10 NPS (delusions, hallucinations, depression, anxiety, euphoria, apathy, disinhibition, aberrant motor behavior, nighttime disturbances and appetite & eating abnormalities) did not differ between sexes. In women the presence of apathy (HR 2.1[1.1;4.3]) was associated with higher risk of clinical progression. In men the presence of depression (HR 2.7[1.4;5.1]) and aberrant motor behavior (HR 2.1[1.1;3.8]) were associated with increased risk of clinical progression.

Conclusion

Manifestations of NPS in patients with possible VCI differ by sex. Different NPS are associated with future clinical progression in men and women. Management strategies of NPS could benefit from sex-specific approaches.

Phenotypic subtypes of progressive dysexecutive syndrome due to Alzheimer's disease: a series of clinical cases

Diagnostic criteria for a progressive dysexecutive syndrome due to Alzheimer's disease (dAD) were proposed. Clinical observations suggest substantial variability in the clinico-radiological profiles within this syndrome. We report a case series of 6 patients with dAD highlighting this heterogeneity. Average age at diagnosis was 57.3 years, and patients were followed annually with clinical, cognitive, and multimodal imaging assessments for an average of 3.7 years. Cases were divided based into three subtypes based on their pattern of FDG-PET hypometabolism: predominantly left parieto-frontal (ldAD), predominantly right parieto-frontal (rdAD), or predominantly biparietal (bpdAD) (n = 2 for each). Prominent executive dysfunction was evidenced in all patients. ldAD cases showed greater impairment on measures of verbal working memory and verbal fluency compared to other subtypes. rdAD cases showed more severe alterations in measures of visual abilities compared to language-related domains and committed more perseverative errors on a measure of cognitive flexibility. bpdAD cases presented with predominant cognitive flexibility and inhibition impairment with relative sparing of working memory and a slower rate of clinical progression. rdAD and bpdAD patients developed neuropsychiatric symptoms, whereas none of the ldAD patients did. For each subtype, patterns of tau deposition relatively corresponded to the spatial pattern of FDG hypometabolism. dAD cases could be differentiated from two clinical cases of atypical AD variants (language and visual) in terms of clinical, cognitive and neuroimaging profiles, suggesting that dAD subtypes represent clinical entities separable from other variants of the disease. The recognition of distinct dAD phenotypes has clinical relevance for diagnosis, prognosis, and symptom management.

White matter hyperintensities-related cortical changes and correlation with mild behavioral impairment

PURPOSE

The aim of this study was to analyze cortical thickness and gray matter volume (GMV) changes in white matter hyperintensities (WMH) which were associated brain regions and their association with mild behavioral impairment (MBI) by means of voxel- and surface-based morphology (VBM and SBM).

METHODS

A total of 60 patients underwent 3T MRI scan and MBI checklist (MBI-C) assessment and were divided into two groups: lower WMH (LWMH) and higher WMH (HWMH). After adjusting for confounding factors i.e. age, gender, education, and total intracranial volume, we found a GMV decrease in the left anterior insula (AIns), right middle frontal gyrus, right central operculum, right fusiform gyrus, left cerebellum exterior, and thalamus proper in the HWMH group based VBM, while in the HWMH group based SBM we found cortical thickness decrease in the left lingual, right posterior cingulate cortex (rPCC), right precentral, left superior frontal, right medial orbitofrontal gyrus, and left pars opercularis.

RESULTS

The HWMH group had higher MBI-C scores. The GMV in the left AIns and thalamus proper and the thickness of rPCC negatively correlated with the MBI-C scores. The mediation analysis suggested that WMH may partially mediate MBI-C scores by reducing the GMV and cortical thickness of the mentioned brain regions.

CONCLUSIONS

In WMH patients, the occurrence of MBI is associated with atrophy of gray matter and cortex. The occurrence of MBI may be partially mediated by WMH through gray matter and cortical atrophy. It provides a new insight into the relationship between WMH and dementia.

Systemic and central nervous system neuroinflammatory signatures of neuropsychiatric symptoms and related cognitive decline in older people

BACKGROUND

Neuroinflammation may contribute to psychiatric symptoms in older people, in particular in the context of Alzheimer's disease (AD). We sought to identify systemic and central nervous system (CNS) inflammatory alterations associated with neuropsychiatric symptoms (NPS); and to investigate their relationships with AD pathology and clinical disease progression.

METHODS

We quantified a panel of 38 neuroinflammation and vascular injury markers in paired serum and cerebrospinal fluid (CSF) samples in a cohort of cognitively normal and impaired older subjects. We performed neuropsychiatric and cognitive evaluations and measured CSF biomarkers of AD pathology. Multivariate analysis determined serum and CSF neuroinflammatory alterations associated with NPS, considering cognitive status, AD pathology, and cognitive decline at follow-up visits.

RESULTS

NPS were associated with distinct inflammatory profiles in serum, involving eotaxin-3, interleukin (IL)-6 and C-reactive protein (CRP); and in CSF, including soluble intracellular cell adhesion molecule-1 (sICAM-1), IL-8, 10-kDa interferon-γ-induced protein, and CRP. AD pathology interacted with CSF sICAM-1 in association with NPS. Presenting NPS was associated with subsequent cognitive decline which was mediated by CSF sICAM-1.

CONCLUSIONS

Distinct systemic and CNS inflammatory processes are involved in the pathophysiology of NPS in older people. Neuroinflammation may explain the link between NPS and more rapid clinical disease progression.

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 Emotional Dyscontrol Following Traumatic Brain Injury: A Systematic Review of Neuroimaging and Electrophysiological Correlates

BACKGROUND

Behavioral and emotional dyscontrol commonly occur following traumatic brain injury (TBI). Neuroimaging and electrophysiological correlates of dyscontrol have not been systematically summarized in the literature to date.

OBJECTIVE

To complete a systematic review of the literature examining neuroimaging and electrophysiological findings related to behavioral and emotional dyscontrol due to TBI.

METHODS

A Preferred Reporting Items for Systematic Reviews and Meta-Analyses-compliant literature search was conducted in PubMed (MEDLINE), PsycINFO, EMBASE, and Scopus databases prior to May 2019. The database query yielded 4392 unique articles. These articles were narrowed based on specific inclusion criteria (e.g., clear TBI definition, statistical analysis of the relationship between neuroimaging and dyscontrol).

RESULTS

A final cohort of 24 articles resulted, comprising findings from 1552 patients with TBI. Studies included civilian (n = 12), military (n = 10), and sport (n = 2) samples with significant variation in the severity of TBI incorporated. Global and region-based structural imaging was more frequently used to study dyscontrol than functional imaging or diffusion tensor imaging. The prefrontal cortex was the most common neuroanatomical region associated with behavioral and emotional dyscontrol, followed by other frontal and temporal lobe findings.

CONCLUSIONS

Frontal and temporal lesions are most strongly implicated in the development of postinjury dyscontrol symptoms although they are also the most frequently investigated regions of the brain for these symptom categories. Future studies can make valuable contributions to the field by (1) emphasizing consistent definitions of behavioral and emotional dyscontrol, (2) assessing premorbid dyscontrol symptoms in subjects, (3) utilizing functional or structural connectivity-based imaging techniques, or (4) restricting analyses to more focused brain regions.

Alzheimer's Disease-Related Psychosis: An Overview of Clinical Manifestations, Pathogenesis, and Current Treatment

Behavioral and psychotic manifestations, including aggression, delusions, and hallucinations, are frequent comorbidities in patients with debilitating nervous illnesses such as Alzheimer's disease (AD), Amyotrophic Lateral Sclerosis, Multiple Sclerosis, and Parkinson's disease. AD-related psychosis may be linked to a poor disease prognosis, highlighting that early detection and management are mandatory. The manifestations are variable and may be very heterogeneous, imposing a real diagnostic issue. Some assessment tools such as BEHAVE-AD, CERAD-BRSD, and the Psycho-Sensory Hallucinations Scale have been designed to facilitate the diagnosis. The mechanisms behind neurodegeneration-related psychosis are complex and are not fully understood, imposing a burden on researchers to find appropriate management modalities. Familial history and some genetic disturbances may have a determinant role in these delusions and hallucinations in cases with AD. The loss of neuronal cells, atrophy in some regions of the central nervous, and synaptic dysfunction may also contribute to these comorbidities. Furthermore, inflammatory disturbances triggered by pro-inflammatory agents such as interleukins and tumor necrosis factors are stratified among the potential risk factors of the onset of numerous psychotic symptoms in Alzheimer's patients. Little is known about the possible management tools; therefore, it is urgent to conduct well-designed trials to investigate pharmacological and non-pharmacological interventions that can improve the care process of these patients. This review summarizes the current findings regarding the AD-related psychosis symptoms, pathological features, assessment, and management.

Enhanced Association of Tau Pathology and Cognitive Impairment in Mild Cognitive Impairment Subjects with Behavior Symptoms

BACKGROUND

Mild cognitive impairment (MCI) individuals with neuropsychiatric symptoms (NPS) are more likely to develop dementia.

OBJECTIVE

We sought to understand the relationship between neuroimaging markers such as tau pathology and cognitive symptoms both with and without the presence of NPS during the prodromal period of Alzheimer's disease.

METHODS

A total of 151 MCI subjects with tau positron emission tomographic (PET) scanning with 18F AV-1451, amyloid-β (Aβ) PET scanning with florbetapir or florbetaben, magnetic resonance imaging, and cognitive and behavioral evaluations were selected from the Alzheimer's Disease Neuroimaging Initiative. A 4-group division approach was proposed using amyloid (A-/A+) and behavior (B-/B+) status: A-B-, A-B+, A+B-, and A+B+. Pearson's correlation test was conducted for each group to examine the association between tau deposition and cognitive performance.

RESULTS

No statistically significant association between tau deposition and cognitive impairment was found for subjects without behavior symptoms in either the A-B-or A+B-groups after correction for false discovery rate. In contrast, tau deposition was found to be significantly associated with cognitive impairment in entorhinal cortex and temporal pole for the A-B+ group and nearly the whole cerebrum for the A+B+ group.

CONCLUSION

Enhanced associations between tauopathy and cognitive impairment are present in MCI subjects with behavior symptoms, which is more prominent in the presence of elevated amyloid pathology. MCI individuals with NPS may thus be at greater risk for further cognitive decline with the increase of tau deposition in comparison to those without NPS.

Altered Interplay Among Large-Scale Brain Functional Networks Modulates Multi-Domain Anosognosia in Early Alzheimer’s Disease

Decline in self-awareness is a prevalent symptom in Alzheimer’s disease (AD). Current data suggest that an early breakdown in the brain’s default mode network (DMN) is closely associated with the main symptomatic features in AD patients. In parallel, the integrity of the DMN has been shown to be heavily implicated in retained self-awareness abilities in healthy individuals and AD patients. However, the global contribution to awareness skills of other large-scale networks is still poorly understood. Resting-state functional magnetic resonance imaging (rs-fMRI) scans were acquired and pre-processed from 53 early-stage AD individuals. A group-level independent component analysis was run to isolate and reconstruct four intrinsic connectivity large-scale brain functional networks, namely left and right central executive fronto-parietal networks (FPN), salience network, and anterior and posterior DMN. Hypothesis-driven seed-based connectivity analyses were run to clarify the region-specific underpinnings of multi-domain anosognosia. Multiple regression models were run on large-scale network- and seed-based connectivity maps, including scores of memory, non-memory and total anosognosia obtained via the Measurement of Anosognosia Questionnaire. Memory anosognosia scores were associated with selective lower fronto-temporal connectivity and higher parieto-temporal connectivity. Non-memory anosognosia scores were associated with higher connectivity between the anterior DMN and the cerebellum, between the left medial prefrontal seeds and the contralateral prefrontal cortex, and between the left hippocampal seed and the left insula; lower connectivity was observed between the right prefrontal cortex and the right lingual seed. Lastly, total anosognosia scores were associated with large-scale network alterations, namely reduced left-FPN expression in the left posterior cingulate, reduced right-FPN expression in the left inferior lingual gyrus and adjacent inferior occipital cortex, and increased right-FPN expression in the right anterior cingulate. Seed-based analyses yielded significant connectivity differences only in the connectivity pattern associated with the left hippocampal seed by displaying lower intercommunication with the right prefrontal cortex, but higher connectivity with the left caudate nucleus. These findings support the hypothesis that alterations in functional connectivity of frontal lobe regions involved in executive-related mechanisms represent the neural correlates of domain-specific anosognosia in early AD. Up-regulated connectivity with subcortical structures appears to contribute to changes in the network dynamics interplay and fosters the appearance of anosognosia.

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

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

Effects of Repetitive Transcranial Magnetic Stimulation in Patients With Mild Cognitive Impairment: A Meta-Analysis of Randomized Controlled Trials

Background: Mild cognitive impairment (MCI) is an intermediary state between normal aging and dementia. It has a high risk of progression in patients with Alzheimer's disease (AD). Repetitive transcranial magnetic stimulation (rTMS) is a non-invasive brain stimulation technique used to improve cognitive deficits in patients with MCI and AD. Although previous meta-analyses included studies carried on patients with MCI and AD, few studies have analyzed patients with MCI independently. This meta-analysis aimed to evaluate the effects and safety of rTMS on cognition function in patients with MCI and factors that may influence such effects. Methods: Data used in this study were searched and screened from different databases, including PubMed, Web of Science, Embase, the Cochrane Library, Chinese National Knowledge Infrastructure (CNKI), Chinese Technical Periodicals (VIP), Wanfang Database, and China BioMedical Literature Database (SinoMed). The retrieved studies were carefully reviewed, data were extracted, and the quality of data was assessed. Results: A total of 12 studies involving 329 patients with MCI were included in the present meta-analysis. The analyses results revealed that rTMS improved cognitive function [standardized mean difference (SMD) = 0.83, 95% confidence interval (CI) = 0.44-1.22, p = 0.0009] and memory function (SMD = 0.73, 95% CI = 0.48-0.97, p < 0.00001) in the MCI + rTMS active group when compared to the sham stimulation group. The showed that: (1) cognitive improvement was more pronounced under high-frequency rTMS stimulation of multiple sites, such as the bilateral dorsolateral prefrontal cortex and (2) more than 10 rTMS stimulation sessions produced higher improvement on cognition function in patients with MCI. Conclusions: This study shows that rTMS can improve cognitive function in patients with MCI, especially when applied at high frequency, multi-site, and for a prolonged period. However, further studies are required to validate these findings and explore more effective stimulation protocols and targets. Systematic Review Registration: [http://www.crd.york.ac.uk/PROSPERO/], identifier: CRD 42021238708.

Extensive frontal focused ultrasound mediated blood-brain barrier opening for the treatment of Alzheimer's disease: a proof-of-concept study

BACKGROUND

Focused ultrasound (FUS)-mediated blood-brain barrier (BBB) opening has shown efficacy in removal of amyloid plaque and improvement of cognitive functions in preclinical studies, but this is rarely reported in clinical studies. This study was conducted to evaluate the safety, feasibility and potential benefits of repeated extensive BBB opening.

METHODS

In this open-label, prospective study, six patients with Alzheimer's disease (AD) were enrolled at Severance Hospital in Korea between August 2020 and September 2020. Five of them completed the study. FUS-mediated BBB opening, targeting the bilateral frontal lobe regions over 20 cm3, was performed twice at three-month intervals. Magnetic resonance imaging, 18F-Florbetaben (FBB) positron emission tomography, Caregiver-Administered Neuropsychiatric Inventory (CGA-NPI) and comprehensive neuropsychological tests were performed before and after the procedures.

RESULTS

FUS targeted a mean volume of 21.1 ± 2.7 cm3 and BBB opening was confirmed at 95.7% ± 9.4% of the targeted volume. The frontal-to-other cortical region FBB standardized uptake value ratio at 3 months after the procedure showed a slight decrease, which was statistically significant, compared to the pre-procedure value (- 1.6%, 0.986 vs1.002, P = 0.043). The CGA-NPI score at 2 weeks after the second procedure significantly decreased compared to baseline (2.2 ± 3.0 vs 8.6 ± 6.0, P = 0.042), but recovered after 3 months (5.2 ± 5.8 vs 8.6 ± 6.0, P = 0.89). No adverse effects were observed.

CONCLUSIONS

The repeated and extensive BBB opening in the frontal lobe is safe and feasible for patients with AD. In addition, the BBB opening is potentially beneficial for amyloid removal in AD patients.

Neuropsychiatric symptoms and brain morphology in patients with mild cognitive impairment and Alzheimer's disease with dementia

We present associations between neuropsychiatric symptoms (NPS) and brain morphology in a large sample of patients with mild cognitive impairment (MCI) and Alzheimer's disease with dementia (AD dementia).Several studies assessed NPS factor structure in MCI and AD dementia, but we know of no study that tested for associations between NPS factors and brain morphology. The use of factor scores increases parsimony and power. For transparency, we performed an additional analysis with selected Neuropsychiatric Inventory - Questionnaire (NPI-Q) items. Including regional cortical thickness, cortical and subcortical volumes, we examined associations between NPS and brain morphology across the whole brain in an unbiased fashion. We reported both statistical significance and effect sizes, using linear models adjusted for multiple comparisons by false discovery rate (FDR). Moreover, we included an interaction term for diagnosis and could thereby compare associations of NPS and brain morphology between MCI and AD dementia.We found an association between the factor elation and thicker right anterior cingulate cortex across MCI and AD dementia. Associations between the factors depression to thickness of the banks of the left superior temporal sulcus and psychosis to the left post-central volume depended on diagnosis: in MCI these associations were positive, in AD dementia negative.Our findings indicate that NPS in MCI and AD dementia are not exclusively associated with atrophy and support previous findings of associations between NPS and mainly frontotemporal brain structures.

OBJECTIVES

Neuropsychiatric symptoms (NPS) are common in mild cognitive impairment (MCI) and Alzheimer’s disease with dementia (AD dementia), but their brain structural correlates are unknown. We tested for associations between NPS and MRI-based cortical and subcortical morphometry in patients with MCI and AD dementia.

DESIGN

Cross-sectional.

SETTINGS

Conducted in Norway.

PARTICIPANTS

Patients with MCI (n = 102) and AD dementia (n = 133) from the Memory Clinic and the Geriatric Psychiatry Unit at Oslo University Hospital.

MEASUREMENTS

Neuropsychiatric Inventory – Questionnaire (NPI-Q) severity indices were reduced using principal component analysis (PCA) and tested for associations with 170 MRI features using linear models and false discovery rate (FDR) adjustment. We also tested for differences between groups. For transparency, we added analyses with selected NPI-Q items.

RESULTS

PCA revealed four factors: elation, psychosis, depression, and motor behavior.FDR adjustment revealed a significant positive association (B = 0.20, pFDR < 0.005) between elation and thickness of the right caudal anterior cingulate cortex (ACC) across groups, and significant interactions between diagnosis and psychosis (B = −0.48, pFDR < 0.0010) on the left post-central volume and between diagnosis and depression (B = −0.40, pFDR < 0.005) on the thickness of the banks of the left superior temporal sulcus. Associations of apathy, anxiety, and nighttime behavior to the left temporal lobe were replicated.

CONCLUSIONS

The positive association between elation and ACC thickness suggests that mechanisms other than atrophy underly elation. Interactions between diagnosis and NPS on MRI features suggest different mechanisms of NPS in our MCI and AD dementia samples. The results contribute to a better understanding of NPS brain mechanisms in MCI and AD dementia.

Neural Correlates of Mild Behavioral Impairment: A Functional Brain Connectivity Study Using Resting-State Functional Magnetic Resonance Imaging

Background:

Mild behavioral impairment (MBI) is associated with accelerated cognitive decline and greater risk of dementia. However, the neural correlates of MBI have not been completely elucidated.

Objective:

The study aimed to investigate the correlation between cognitively normal participants and participants with amnestic mild cognitive impairment (aMCI) using resting-state functional magnetic resonance imaging.

Methods:

The study included 30 cognitively normal participants and 13 participants with aMCI (20 men and 23 women; mean age, 76.9 years). The MBI was assessed using the MBI checklist (MBI-C). Region of interest (ROI)-to-ROI analysis was performed to examine the correlation between MBI-C scores and functional connectivity (FC) of the default mode network, salience network, and frontoparietal control network (FPCN). Age, Mini-Mental State Examination score, sex, and education were used as covariates. A p-value of 0.05, with false discovery rate correction, was considered significant.

Results:

A negative correlation was observed between the MBI-C total score and FC of the left posterior parietal cortex with the right middle frontal gyrus. A similar result was obtained for the MBI-C affective dysregulation domain score.

Conclusion:

FPCN dysfunction was detected as a neural correlate of MBI, especially in the affective dysregulation domain. This dysfunction may be associated with cognitive impairment in MBI and conversion of MBI to dementia; however, further longitudinal data are needed to examine this relationship.

Mild Behavioral Impairment Is Associated With Atrophy of Entorhinal Cortex and Hippocampus in a Memory Clinic Cohort

Objectives

Mild behavioral impairment (MBI) is a syndrome describing late-onset persistent neuropsychiatric symptoms (NPS) in non-demented older adults. Few studies to date have investigated the associations of MBI with structural brain changes. Our aim was to explore structural correlates of NPS in a non-demented memory clinic sample using the Mild Behavioral Impairment Checklist (MBI-C) that has been developed to measure MBI.

Methods

One hundred sixteen non-demented older adults from the Czech Brain Aging Study with subjective cognitive concerns were classified as subjective cognitive decline (n = 37) or mild cognitive impairment (n = 79). Participants underwent neurological and neuropsychological examinations and brain magnetic resonance imaging (MRI) (1.5 T). The Czech version of the MBI-C was administered to participants’ informants. Five a priori selected brain regions were measured, namely, thicknesses of the orbitofrontal cortex (OFC), anterior cingulate cortex (ACC), posterior cingulate cortex (PCC), and entorhinal cortex (ERC) and volume of the hippocampus (HV), and correlated with MBI-C total and domain scores.

Results

Entorhinal cortex was associated with MBI-C total score (r_S = −0.368, p < 0.001) and with impulse dyscontrol score (r_S = −0.284, p = 0.002). HV was associated with decreased motivation (r_S = −0.248, p = 0.008) and impulse dyscontrol score (r_S = −0.240, p = 0.011).

Conclusion

Neuropsychiatric symptoms, particularly in the MBI impulse dyscontrol and motivation domains, are associated with medial temporal lobe atrophy in a clinical cohort of non-demented older adults. This study supports earlier involvement of temporal rather than frontal regions in NPS manifestation. Since these regions are typically affected early in the course of Alzheimer’s disease (AD), the MBI-C may potentially help further identify individuals at-risk of developing AD dementia.

Brain Volume Predicts Behavioral and Psychological Symptoms in Alzheimer's Disease

BACKGROUND

Behavioral and psychological symptoms of dementia (BPSD) are frequent and troublesome for patients and caregivers. Considering possible preventive approaches, a better understanding of underlying neural correlates of BPSD is crucial.

OBJECTIVE

The aim is to assess whether brain regional volume predicts behavioral changes in mild AD.

METHODS

This work took part from the PACO study, a multicenter and prospective study that included 252 patients with mild AD from 2009 to 2014. Fifty-three patients were retained. Forty healthy matched control subjects from the ADNI cohort were included as controls. Voxel-based morphometry analysis was conducted to assess regional brain volume using baseline MRI scans as a predictor of future behavioral changes over a period of 18 months. Behavior was assessed at baseline and longitudinally at 6-month intervals using the shortened form of the Neuropsychiatric Inventory (NPI).

RESULTS

The volume of 23 brain structures in frontal, temporal, parietal, occipital, subcortical regions and cerebellum predicted the evolution of NPI scores. Frontal volume was the most powerful predictor with frontal gyri, anterior cingulate cortex, and orbital gyri being particularly involved.

CONCLUSION

To our knowledge, this is the first study assessing regional brain volumes as predictors of behavioral changes considered at earlier stages of AD. Up to 23 brain structures were associated with an increased risk of developing BPSD. Frontal lobe volume was the strongest predictor of future evolution of NPI. The involvement of multiple structures in the prediction of behavior suggests a role of the main large-scale networks involved in cognition.

A Scoping Review of Cognitive Training in Neurodegenerative Diseases via Computerized and Virtual Reality Tools: What We Know So Far

Most prevalent neurodegenerative diseases such as Alzheimer's disease, frontotemporal dementia, Parkinson's disease and multiple sclerosis are heterogeneous in their clinical profiles and underlying pathophysiology, although they typically share the presence of cognitive impairment that worsens significantly during the course of the disease. Viable pharmacological options for cognitive symptoms in these clinical conditions are currently lacking. In recent years, several studies have started to apply Computerized Cognitive Training (CCT) and Virtual Reality (VR) tools to try and contrast patients' cognitive decay over time. However, no in-depth literature review of the contribution of these promising therapeutic options across main neurodegenerative diseases has been conducted yet. The present paper reports the state-of-the-art of CCT and VR studies targeting cognitive impairment in most common neurodegenerative conditions. Our twofold aim is to point out the scientific evidence available so far and to support health professionals to consider these promising therapeutic tools when planning rehabilitative interventions, especially when the access to regular and frequent hospital consultations is not easy to be provided.

Benedet A, Thomas EM, Parsons M, Nasreddine Z, Rosa‐Neto P, Gauthier S. Association between regional tau pathology and neuropsychiatric symptoms in aging and dementia due to Alzheimer's disease

BACKGROUND

Neuropsychiatric symptoms (NPS) are frequent in aging and Alzheimer's disease (AD). Here we study the relationship between NPS and AD pathologies in vivo.

METHOD

Two hundred and twenty-one individuals from the TRIAD cohort (143 cognitively unimpaired, 52 mild cognitive impairment, and 26 AD) underwent [18F]MK6240-tau-positron emission tomography (PET), [18F]AZD4694-amyloid-PET, magnetic resonance imaging, and neuropsychological evaluations. Spearman correlations and voxel-based regression models evaluated the relationship between Neuropsychiatric Inventory Questionnaire (NPI-Q) scores, and tau-PET, amyloid-PET, and voxel-based morphometry.

RESULTS

Fifty percent of individuals presented NPS; these correlated with tau, not amyloid beta or neurodegeneration. Associations between NPI-Q score and tau-PET were stronger in the parietal association area, superior frontal, temporal, and medial occipital lobes. NPI-Q domains associated with distinct patterns of tau uptake.

CONCLUSIONS

NPS are predominantly related to tau in aging and dementia. Regions affected are part of the behavioral circuits, and vulnerable to early AD pathology. Domain-specific analyses showed NPS are related to the AD pathophysiological processes in a symptom-specific manner.

Differential insular cortex sub-regional atrophy in neurodegenerative diseases: a systematic review and meta-analysis

The insular cortex is proposed to function as a central brain hub characterized by wide-spread connections and diverse functional roles. As a result, its centrality in the brain confers high metabolic demands predisposing it to dysfunction in disease. However, the functional profile and vulnerability to degeneration varies across the insular sub-regions. The aim of this systematic review and meta-analysis is to summarize and quantitatively analyze the relationship between insular cortex sub-regional atrophy, studied by voxel based morphometry, with cognitive and neuropsychiatric deficits in frontotemporal dementia (FTD), Alzheimer’s disease (AD), Parkinson’s disease (PD), and dementia with Lewy bodies (DLB). We systematically searched through Pubmed and Embase and identified 519 studies that fit our criteria. A total of 41 studies (n = 2261 subjects) fulfilled the inclusion criteria for the meta-analysis. The peak insular coordinates were pooled and analyzed using Anatomic Likelihood Estimation. Our results showed greater left anterior insular cortex atrophy in FTD whereas the right anterior dorsal insular cortex showed larger clusters of atrophy in AD and PD/DLB. Yet contrast analyses did not reveal significant differences between disease groups. Functional analysis showed that left anterior insular cortex atrophy is associated with speech, emotion, and affective-cognitive deficits, and right dorsal atrophy with perception and cognitive deficits. In conclusion, insular sub-regional atrophy, particularly the anterior dorsal region, may contribute to cognitive and neuropsychiatric deficits in neurodegeneration. Our results support anterior insular cortex vulnerability and convey the differential involvement of the insular sub-regions in functional deficits in neurodegenerative diseases.

Eating Disorders in Frontotemporal Dementia and Alzheimer's Disease: Evaluation of Brain Perfusion Correlates Using 99mTc-HMPAO SPECT with Brodmann Areas Analysis

BACKGROUND

Eating disorders (ED) in dementia represent a significant impairment affecting patients' and caregivers' lives. In frontotemporal dementia (FTD), ED include overeating, sweet food preference, stereotypical eating, and hyperorality, while in Alzheimer's disease (AD), anorexia and appetite loss are the most common ED.

OBJECTIVE

The aim of our study was to highlight Brodmann areas (BAs) implicated specifically in the appearance of ED in FTD and AD.

METHODS

We studied 141 patients, 75 with FTD and 66 with AD. We used the NeuroGamTM software on the reconstructed single photon emission computed tomography-SPECT data for the automated comparison of BAs perfusion on the left (L) and right (R) hemisphere with perfusion in corresponding BAs of a normal database.

RESULTS

The FTD group included 27 men and 48 women, age (mean±SD) 65.8±8.5 years, duration of disease 3.4±3.3 years, Mini-Mental State Examination (MMSE) 17.9±8.6, ED score on Neuropsychiatric Inventory (NPI) 4.7±8.5. ED in FTD were correlated with hypoperfusion in right anterior and dorsolateral prefrontal cortices (BAs 10R, 46R), left orbitofrontal cortex (BA 12L), orbital part of the right inferior frontal gyrus (BA 47R), and left parahippocampal gyrus (BA 36L). The AD group included 21 men and 45 women, age (mean±SD) 70.2±8.0 years, duration of disease 3.3±2.4 years, MMSE 20.2±6, ED-NPI score 2.7±3.9. ED in AD were correlated with hypoperfusion in left inferior temporal cortex (BA 20L).

CONCLUSION

SPECT imaging with automated mapping of brain cortex could contribute to the understanding of the neural networks involved in the manifestation of ED in dementia.

Correlation of Frontal Atrophy and CSF Tau Levels With Neuropsychiatric Symptoms in Patients With Cognitive Impairment: A Memory Clinic Experience

Background: Behavioral and psychological symptoms of dementia (BPSD) are a distressful condition. We aimed to investigate the BPSD distribution in subjects with cognitive impairment, and the potential correlations between BPSD and neurodegeneration in terms of cerebrospinal fluid (CSF) tau and brain atrophy.

Methods: One-hundred patients with mild cognitive impairment (MCI) or dementia (Alzheimer’s disease, AD; Lewy-body disease, LBD; frontotemporal dementia, FTD; vascular dementia, VD) underwent a complete diagnostic workup, including 3T-MRI and/or CT and CSF. Cortical atrophy was assessed with medial temporal atrophy (MTA), posterior atrophy (PA), and global cortical atrophy-frontal lobe (GCA-F) scales. BPSD were rated using the Neuropsychiatric Inventory (NPI), and BPSD clusters were defined according to the European Alzheimer Disease Consortium.

Results: Delusions, hallucinations, and psychosis cluster were differently distributed among the diagnostic groups (p < 0.05, p < 0.001, and p < 0.05), with LBD patients showing higher scores for hallucinations (vs. MCI, p < 0.001, and AD, p < 0.05) and psychosis cluster (vs. MCI, p < 0.05). In primary dementias, we found a negative correlation between NPI total score and tau levels (p = 0.08), confirmed by beta regression (p < 0.01), while a positive non-significant relationship was observed in MCI. Higher GCA-F scores were associated with delusions and apathy (p < 0.05, on both hemispheres) and hallucinations (left: p < 0.01, right: p < 0.05). GCA-F scores were positively correlated with psychosis cluster (right: p < 0.05), and agitation/aggression (left: p < 0.05). Conversely, nighttime disturbances were positively correlated with both GCA-F and MTA scores (left: p < 0.01; right: p < 0.05).

Conclusion: Our results suggest that psychotic symptoms are significantly more represented in LBD patients and that CSF tau and frontal atrophy are associated with the occurrence and severity of BPSD in clinical practice. Longitudinal studies are however required to ascertain their actual predictive value.

A Scoping Review of Neuromodulation Techniques in Neurodegenerative Diseases: A Useful Tool for Clinical Practice?

Background and Objectives: Neurodegenerative diseases that typically affect the elderly such as Alzheimer’s disease, Parkinson’s disease and frontotemporal dementia are typically characterised by significant cognitive impairment that worsens significantly over time. To date, viable pharmacological options for the cognitive symptoms in these clinical conditions are lacking. In recent years, various studies have employed neuromodulation techniques to try and contrast patients’ decay. Materials and Methods: We conducted an in-depth literature review of the state-of-the-art of the contribution of these techniques across these neurodegenerative diseases. Results: The present review reports that neuromodulation techniques targeting cognitive impairment do not allow to draw yet any definitive conclusion about their clinical efficacy although preliminary evidence is very encouraging. Conclusions: Further and more robust studies should evaluate the potentialities and limitations of the application of these promising therapeutic tools to neurodegenerative diseases.

Altered Cerebral Blood Flow in Alzheimer's Disease With Depression

Background: Depression is common in Alzheimer's disease (AD) with an unclear neural mechanism. This study aimed to investigate the underlying cerebral perfusion associated with depression in AD and evaluate its clinical significance. Method: Twenty-one AD patients and 21 healthy controls (HCs) were enrolled in this study. The depressive symptom was defined according to the Hamilton Depression Rating Scale (HAMD). Nine patients were diagnosed as AD with depression symptoms (HAMD >7). Three-dimensional pseudocontinuous arterial spin labeling MR imaging was conducted to measure regional cerebral blood flow (CBF). Neuropsychological tests covered cognition and depressive scores. Between-group comparisons on clinical variables and regional CBFs, relationship between regional CBF and depressive score, and identification of AD patients with depression were performed using covariance analysis, linear regression, and receiver operating characteristic (ROC) analysis, respectively. Results: Compared with HCs, AD patients without depression exhibited lower gray matter CBF (p = 0.016); compared with AD patients without depression, AD patients with depression had higher CBF in the right supplementary motor area (39.23 vs. 47.91 ml/100 g/min, p = 0.017) and right supramarginal gyrus (35.54 vs. 43.85 ml/100 g/min, p = 0.034). CBF in the right supplementary motor area was correlated with depressive score (β = 0.46, p = 0.025). The combination of CBF in the right supplementary motor area and supramarginal gyrus and age could identify AD patients with depression from those without depression with a specificity of 100%, sensitivity of 66.67%, accuracy of 85.71%, and area under the curve of 0.87. Conclusions: Our findings suggested that hyperperfusion of the right supplementary motor area and right supramarginal gyrus were associated with depression syndrome in AD, which could provide a potential neuroimaging marker to evaluate the depression state in AD.

The Longitudinal Assessment of Neuropsychiatric Symptoms in Mild Cognitive Impairment and Alzheimer's Disease and Their Association With White Matter Hyperintensities in the National Alzheimer's Coordinating Center's Uniform Data Set

BACKGROUND

Neuropsychiatric symptoms (NPSs) are common in Alzheimer's disease (AD). NPSs contribute to patients' distress, caregiver burden, and institutionalization. White matter hyperintensities (WMHs) appear on magnetic resonance imaging, usually indicative of cerebrovascular disease. WMHs have been associated with certain NPSs. We aimed to assess the relationship between WMH and NPS severity in mild cognitive impairment (MCI) due to AD (MCI-AD) and in AD and to assess the ability of WMHs to predict NPS progression. Data were obtained from the National Alzheimer's Coordinating Center.

METHODS

A total of 252 participants (114 with MCI-AD and 138 with AD) were used in this study. Baseline WMHs were quantified using an automated segmentation technique. NPSs were measured using the Neuropsychiatric Inventory. Mixed-effect models and correlations were used to determine the relationship between WMHs and NPSs.

RESULTS

Longitudinal mixed-effect models revealed a significant relationship between increase in Neuropsychiatric Inventory total scores and baseline WMHs (p = .014). There was a significant relationship between baseline WMHs and an increase in delusions (p = .023), hallucinations (p = .040), agitation (p = .093), depression (p = .017), and irritability (p = .002). Correlation plot analysis showed that baseline whole-brain WMHs predicted change in future Neuropsychiatric Inventory total scores (r = .169, p = .008) and predicted change in future agitation severity scores (r = .165, p = .009). WMHs in the temporal lobes (r = .169, p = .008) and frontal lobes (r = .153, p = .016) contributed most to this change.

CONCLUSIONS

Depression, irritability, and agitation are common NPSs and very distressful to patients and caregivers. Our findings of increased NPS severity over time in MCI-AD and AD with increased WMHs have important implications for treatment, arguing for aggressive treatment of vascular risk factors in patients with MCI-AD or AD.

White matter hyperintensities and neuropsychiatric symptoms in mild cognitive impairment and Alzheimer's disease

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White matter hyperintensities play a larger role than grey matter atrophy in neuropsychiatric symptoms in AD/MCI.

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Greater white matter hyperintensities are related to lower grey matter volumes.

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Frontotemporal atrophy implicated in neuropsychiatric symptoms.

Neuropsychiatric symptoms (NPS), such as apathy, irritability and depression, are frequently encountered in patients with Alzheimer’s disease (AD). Focal grey matter atrophy has been linked to NPS development. Cerebrovascular disease is common among AD patients and can be detected on MRI as white matter hyperintensities (WMH). In this longitudinal study, the relative contribution of WMH burden and GM atrophy to NPS was evaluated in a cohort of mild cognitive impairment (MCI), AD and normal controls. This study included 121 AD, 315 MCI and 225 normal control subjects from the Alzheimer’s Disease Neuroimaging Initiative. NPS were assessed using the Neuropsychiatric Inventory and grouped into hyperactivity, psychosis, affective and apathy subsyndromes. WMH were measured using an automatic segmentation technique and mean deformation-based morphometry (DBM) was used to measure atrophy of grey matter regions. Linear mixed-effects models found focal grey matter atrophy and WMH volume both contributed significantly to NPS subsyndromes in MCI and AD subjects, however, WMH burden played a greater role. This study could provide a better understanding of the pathophysiology of NPS in AD and support the monitoring and control of vascular risk factors.

Amygdala: Neuroanatomical and Morphophysiological Features in Terms of Neurological and Neurodegenerative Diseases

The amygdala is one of the most discussed structures of the brain. Correlations between its level of activity, size, biochemical organization, and various pathologies are the subject of many studies, and can serve as a marker of existing or future disease. It is hypothesized that the amygdala is not just a structural unit, but includes many other regions in the brain. In this review, we present the updated neuroanatomical and physiological aspects of the amygdala, discussing its involvement in neurodegenerative and neurological diseases. The amygdala plays an important role in the processing of input signals and behavioral synthesis. Lesions in the amygdala have been shown to cause neurological disfunction of ranging severity. Abnormality in the amygdala leads to conditions such as depression, anxiety, autism, and also promotes biochemical and physiological imbalance. The amygdala collects pathological proteins, and this fact can be considered to play a big role in the progression and diagnosis of many degenerative diseases, such as Alzheimer’s disease, chronic traumatic encephalopathy, Lewy body diseases, and hippocampal sclerosis. The amygdala has shown to play a crucial role as a central communication system in the brain, therefore understanding its neuroanatomical and physiological features can open a channel for targeted therapy of neurodegenerative diseases.

Enteromorpha prolifera Extract Improves Memory in Scopolamine-Treated Mice via Downregulating Amyloid-β Expression and Upregulating BDNF/TrkB Pathway

Enteromorpha prolifera, a green alga, has long been used in food diets as well as traditional remedies in East Asia. Our preliminary study demonstrated that an ethyl acetate extract of Enteromorpha prolifera (EAEP) exhibited the strongest antioxidant activity compared to ethanol or water extracts. Nonetheless, there has been no report on the effect of EAEP on memory impairment due to oxidative damage. This study investigated whether EAEP could attenuate memory deficits in an oxidative stress-induced mouse model. EAEP was orally administered (50 or 100 mg/kg body weight (b.w.)) to mice and then scopolamine was administered. The oral administration of EAEP at 100 mg/kg b.w. significantly restored memory impairments induced by scopolamine, as evaluated by the Morris water maze test, and the passive avoidance test. Further, EAEP upregulated the protein expression of BDNF, p-CREB, p-TrkB, and p-Akt. Moreover, EAEP downregulated the expression of amyloid-β, tau, and APP. The regulation of cholinergic marker enzyme activities and the protection of neuronal cells from oxidative stress-induced cell death in the brain of mice via the downregulation of amyloid-β and the upregulation of the BDNF/TrkB pathway by EAEP suggest its potential as a pharmaceutical candidate to prevent neurodegenerative diseases.

Neuropsychiatric symptoms as prognostic makers for the elderly with mild cognitive impairment: a meta-analysis

BACKGROUND

Although several neuropsychiatric symptoms (NPSs) have been demonstrated to have value in the prediction of the progression of mild cognitive impairment (MCI) to dementia, these symptoms are less studied for the prediction of the transition from normal cognition (NC) to MCI.

METHODS

Prospective cohort studies were included if they reported on at least one NPS at baseline and had MCI as the outcome.

RESULTS

We obtained 13 cohort studies with a total population of 33,066. Depression was the most common neuropsychiatric symptom and could significantly predict transition to MCI (RR = 1.49, 95% CI: 1.13-1.86). However, depression was more capable of predicting amnestic MCI (RR=1.43, 95% CI: 1.04-1.83) than non-aMCI (RR= 0.96, 95% CI 95% CI: 0.60-1.33). Subgroup analysis suggested that the association between depression and MCI changed with depression severity, depression criteria, apolipoprotein-E-adjusted status, age, the percentage of females, and follow-up times, but some data were too sparse for a reliable estimate. Regarding other NPSs, there were insufficient data to assess their effect on the development of MCI. However, apathy, anxiety, sleep disturbances, irritability, and agitation might be risk factors for the prediction of NC-MCI transition with strong predictive value.

CONCLUSIONS

Depression was associated with an approximately 1.5-fold sincreased risk of the progression to MCI in the population with normal cognition. Other NPSs with underlying predictive value deserve more attention.

Neuropsychiatric Aspects of Alzheimer Dementia: From Mechanism to Treatment

Developing disease-modifying treatments for Alzheimer dementia requires innovative approaches to identify novel biological targets during the course of the disease. Treatment development for the neuropsychiatric symptoms of Alzheimer may benefit from a mechanistic approach to treatment. There has been progress in identifying mild forms of behavioral impairment along the Alzheimer spectrum that may lead to additional insights into progression to dementia as well as the fundamental mechanisms of the symptoms. Developing therapies for complex neurobehavioral syndromes may require the translation of mechanistic insights into therapy, which may both improve the symptoms and delay progression to dementia in certain patients.