The Role of Hub and Spoke Regions in Theory of Mind in Early Alzheimer's Disease and Frontotemporal Dementia

Clinical and metabolic profiles in behavioural frontotemporal dementia: Impact of age at onset

AIM

Frontotemporal dementia (FTD) is a heterogeneous neurodegenerative disorder, with considerable variability of age-at-onset. We explored clinical and metabolic differences between early- and late-onset behavioural FTD (bvFTD), assuming that they might represent different disease phenotypes.

MATERIALS AND METHODS

We retrospectively studied consecutive patients diagnosed with prodromal or overt bvFTD with [18F]FDG PET scan, neuropsychological assessment (NPS), and Neuropsychiatric Inventory (NPI) available at baseline. Patients were divided into three groups based on age-at-onset: early onset-bvFTD (EO-bvFTD, age<70), late onset-bvFTD (LO-bvFTD, age 70-75) and very late onset-bvFTD (vLO-bvFTD, age>75). NPS and NPI were compared between groups and in the subset of prodromal patients, to study different syndromic phenotypes. Voxel-based analysis compared brain [18F]FDG PET of EO-bvFTD, LO-bvFTD and vLO-bvFTD independently, with respect to healthy controls, to explore metabolic differences. An inter-regional metabolic covariance analysis was performed in frontal lobe subregions, to explore differences in brain connectivity. Moreover, we supported our result using a correlation-based approach on clinical and metabolic variables.

RESULTS

101 bvFTD (62 prodromal bvFTD) were enrolled (EO-bvFTD: n = 36, prodromal n = 21; LO-bvFTD: n = 36, prodromal: n = 22; vLO-bvFTD: n = 29, prodromal: n = 19). Greater verbal memory deficit was evident in LO-bvFTD and vLO-bvFTD compared to EO-bvFTD (immediate recall: p = .018; p = .024; delayed recall: both p = .001, respectively), with similar results in the subset of prodromal patients. EO-bvFTD and LO-bvFTD had a higher behavioural severity than vLO-bvFTD. LO-bvFTD and vLO-bvFTD showed more widespread relative hypometabolism, with a greater involvement of posterior, subcortical and temporo-limbic regions compared with EO-bvFTD. Moreover, vLO-bvFTD showed a different pattern of intrafrontal metabolic covariance compared to EO-bvFTD and LO-bvFTD.

DISCUSSION

The cognitive-behavioural profile of bvFTD differs between early- and late-onset, already from the prodromal stage of the disease. Both metabolic pattern and functional connectivity vary based on age-at-onset. Understanding these differences could contribute to improve diagnostic accuracy and understanding the underling pathological heterogeneity.

Tinnitus: Does it Lead to Impairments in Metacognitive Functions and the Theory of Mind Skills?

Objective

This study aimed to investigate theory of mind skills and metacognitive functions in patients with tinnitus compared to healthy controls.

Methods

This prospective study included patients diagnosed with tinnitus at our otolaryngology and Head and Neck Surgery clinic and healthy controls matching their demographic characteristics. Patients diagnosed with tinnitus at our otolaryngology and head and neck surgery clinic, along with healthy controls matched for demographic characteristics, were included in the study. All participants completed the Reading the Mind in the Eyes Test (RMET), the metacognition questionnaire (MCQ-30), the Beck Depression Inventory (BDI), and the Tinnitus Handicap Inventory (THI). The relationship between the scales applied to the patient group regarding tinnitus was evaluated using Spearman's and Pearson's correlation tests.

Results

A total of 90 individuals diagnosed with tinnitus and 70 healthy controls participated in the study. There was no statistically significant difference in BDI scores between the groups (p>0.05). However, in the MCQ-30, the cognitive awareness subscale and the total score were significantly higher in the tinnitus group (p=0.003 and p=0.041, respectively). Additionally, RMET performance was lower in tinnitus patients compared to healthy controls (p=0.002). Certain subscales of the MCQ-30 showed a moderate positive correlation with THI.

Conclusion

Based on these findings, we suggest that evaluating tinnitus patients from a psychiatric perspective, providing psychosocial support, and assisting them in improving their communication skills could be beneficial.

Validation of the Cognitive-Emotional Perspective Taking test in patients with neurodegeneration

BackgroundTheory of mind (ToM) is crucial for socioemotional interaction. ToM deficits may explain behavioral changes in dementia, especially Alzheimer's disease (AD) and frontotemporal dementia (FTD).ObjectiveThis study examined the psychometrics of a new ToM test in healthy adults, identified ToM differences in dementia syndromes, and assessed if ToM scores predict neuropsychiatric function and real-life behavior.MethodsThe UCSF Cognitive and Emotional Perspective Taking Test (CEPT) was evaluated in 195 healthy adults (age: 42.69 ± 16.20) and in a clinic cohort of 304 participants (age: 64.07 ± 9.2). Participants included healthy controls, AD, behavioral-variant frontotemporal dementia (bvFTD), semantic variant primary progressive aphasia (svPPA), non-fluent PPA (nfvPPA), and progressive supranuclear palsy (PSP) patients. CEPT's psychometrics were assessed, and ToM differences and predictions of neuropsychiatric symptoms were analyzed using regression models.ResultsIn controls, CEPT showed good validity and reliability. In patients, CEPT scores correlated with executive and emotional measures, but not language measures, showing good construct validity. Cognitive ToM was most impaired in AD and bvFTD, with less impairment in svPPA and PSP, and all patient groups showed impaired emotional ToM. ToM performance predicted real-life neuropsychiatric behavior, including anxiety, apathy, disinhibition, and aberrant motor behaviors.ConclusionsToM deficits appear early in dementia syndromes and predict neuropsychiatric behavior. Assessing ToM and social cognition with ecologically valid tasks may help identify altered social cognition in early neurodegeneration.

Understanding basic and social emotions in Alzheimer's disease and frontotemporal dementia

Introduction

Recent developments in the field of social cognition have led to a renewed interest in basic and social emotion recognition in early stages of Alzheimer's Disease (AD) and FrontoTemporal Dementia (FTD). Despite the growing attention to this issue, only few studies have attempted to investigate emotion recognition using both visual and vocal stimuli. In addition, recent studies have presented conflicting findings regarding the extent of impairment in patients in the early stages of these diseases. The present study aims to investigate emotion understanding (both basic and social emotions), using different tasks with visual and auditory stimuli, to identify supramodal deficits in AD and FTD to provide a reliable tool to better outline their behavioral and emotional profile and useful instruments for their management.

Methods

Eighteen patients with AD and 15 patients with FTD were included in the study. Healthy control (HCs) subjects were recruited to obtain normative data for basic emotion recognition tests and social emotion recognition tasks. To evaluate basic emotion recognition, the Facial Emotion Recognition Battery (FERB) and the Emotional Prosody Recognition Battery (EPRB) were administered. To evaluate social emotion recognition, the Faux Pas (FP), Reading the Mind in the Eyes (RME), and Reading the Mind in the Voice (RMV) tests were employed.

Results

FTD patients performed significantly worse than HCs in most of the subtests of the basic emotion recognition batteries, where, instead, AD patients were significantly impaired only when required to match emotional facial expression in different individuals (subtask of the FERB). Moreover, FTD patients scored significantly lower in RME and RMV tests compared both to AD patients and to HCs. In addition, ADs were selectively impaired in RMV as respect to HCs.

Discussion

FTD patients showed deficits in emotion recognition, affecting both basic and social emotions, whether conveyed through facial expressions or prosody. This result may explain the well-known social behavioral difficulties observed in FTD patients from the early stages of the disease. The fewer and specific deficits in AD patients with comparable MMSE scores may be attributed to the mild degree of impairment, as these deficits may appear later in the progression of AD.

Relationship between neuroimaging and emotion recognition in mild cognitive impairment patients

OBJECTIVE

Dementia is a major public health problem with high needs for early detection, efficient treatment, and prognosis evaluation. Social cognition impairment could be an early dementia indicator and can be assessed with emotion recognition evaluation tests. The purpose of this study is to investigate the link between different brain imaging modalities and cognitive status in Mild Cognitive Impairment (MCI) patients, with the goal of uncovering potential physiopathological mechanisms based on social cognition performance.

METHODS

The relationship between the Reading the Mind in the Eyes Test (RMET) and some clinical and biochemical variables ([18 F]FDG PET-CT and anatomical MR parameters, neuropsychological evaluation, and CSF biomarkers) was studied in 166 patients with MCI by using a correlational approach.

RESULTS

The RMET correlated with neuropsychological variables, as well as with structural and functional brain parameters obtained from the MR and FDG-PET imaging evaluation. However, significant correlations between the RMET and CSF biomarkers were not found.

DISCUSSION

Different neuroimaging parameters were found to be related to an emotion recognition task in MCI. This analysis identified potential minimally-invasive biomarkers providing some knowledge about the physiopathological mechanisms in MCI.

The Tryptophan-Kynurenine Metabolic System Is Suppressed in Cuprizone-Induced Model of Demyelination Simulating Progressive Multiple Sclerosis

Progressive multiple sclerosis (MS) is a chronic disease with a unique pattern, which is histologically classified into the subpial type 3 lesions in the autopsy. The lesion is also homologous to that of cuprizone (CPZ) toxin-induced animal models of demyelination. Aberration of the tryptophan (TRP)-kynurenine (KYN) metabolic system has been observed in patients with MS; nevertheless, the KYN metabolite profile of progressive MS remains inconclusive. In this study, C57Bl/6J male mice were treated with 0.2% CPZ toxin for 5 weeks and then underwent 4 weeks of recovery. We measured the levels of serotonin, TRP, and KYN metabolites in the plasma and the brain samples of mice at weeks 1, 3, and 5 of demyelination, and at weeks 7 and 9 of remyelination periods by ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) after body weight measurement and immunohistochemical analysis to confirm the development of demyelination. The UHPLC-MS/MS measurements demonstrated a significant reduction of kynurenic acid, 3-hydoxykynurenine (3-HK), and xanthurenic acid in the plasma and a significant reduction of 3-HK, and anthranilic acid in the brain samples at week 5. Here, we show the profile of KYN metabolites in the CPZ-induced mouse model of demyelination. Thus, the KYN metabolite profile potentially serves as a biomarker of progressive MS and thus opens a new path toward planning personalized treatment, which is frequently obscured with immunologic components in MS deterioration.

Theory of mind in patients with mild cognitive impairment: A systematic review

The focus of this systematic review was to collect and align studies which analyze the functionality of theory of mind (TOM) in patients with mild cognitive impairments (MCI). Specifically, we identified 20 papers published between 2012 and 2022 which met inclusion criteria. Papers search, selection, and extraction followed the PRISMA guidelines. In order to summarize data from the papers, we used a narrative synthesis approach. Results in 18 of these 20 papers show that theory of mind (TOM) is impaired in all types of MCI patients—regardless of different etiology and diagnostic criteria. Only 2 out of 20 reported no significant differences in TOM performance between MCI patients and healthy control subjects. The review additionally aimed to bundle the variety of the type of tasks used by the author to assess multiple domains of TOM. This heterogeneity does not allow us to make a comprehensive comparison between the results, so we suggest the need to align the results using the same type of tests and TOM assessment. In the end, our work highlights the 2 neuropsychological studies which confirm more of our results; due to the objective approach adopted to investigate this topic, we suggest exploring this point of view more in future research.

Mitochondrial Impairment: A Common Motif in Neuropsychiatric Presentation? The Link to the Tryptophan-Kynurenine Metabolic System

Nearly half a century has passed since the discovery of cytoplasmic inheritance of human chloramphenicol resistance. The inheritance was then revealed to take place maternally by mitochondrial DNA (mtDNA). Later, a number of mutations in mtDNA were identified as a cause of severe inheritable metabolic diseases with neurological manifestation, and the impairment of mitochondrial functions has been probed in the pathogenesis of a wide range of illnesses including neurodegenerative diseases. Recently, a growing number of preclinical studies have revealed that animal behaviors are influenced by the impairment of mitochondrial functions and possibly by the loss of mitochondrial stress resilience. Indeed, as high as 54% of patients with one of the most common primary mitochondrial diseases, mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, present psychiatric symptoms including cognitive impairment, mood disorder, anxiety, and psychosis. Mitochondria are multifunctional organelles which produce cellular energy and play a major role in other cellular functions including homeostasis, cellular signaling, and gene expression, among others. Mitochondrial functions are observed to be compromised and to become less resilient under continuous stress. Meanwhile, stress and inflammation have been linked to the activation of the tryptophan (Trp)-kynurenine (KYN) metabolic system, which observably contributes to the development of pathological conditions including neurological and psychiatric disorders. This review discusses the functions of mitochondria and the Trp-KYN system, the interaction of the Trp-KYN system with mitochondria, and the current understanding of the involvement of mitochondria and the Trp-KYN system in preclinical and clinical studies of major neurological and psychiatric diseases.

Analyzing of Alzheimer’s Disease Based on Biomedical and Socio-Economic Approach Using Molecular Communication, Artificial Neural Network, and Random Forest Models

Alzheimer’s disease will affect more people with increases in the elderly population, as the elderly population of countries everywhere generally rises significantly. However, other factors such as regional climates, environmental conditions and even eating and drinking habits may trigger Alzheimer’s disease or affect the life quality of individuals already suffering from this disease. Today, the subject of biomedical engineering is being studied intensively by many researchers considering that it has the potential to produce solutions to various diseases such as Alzheimer’s caused by problems in molecule or cell communication. In this study, firstly, a molecular communication model with the potential to be used in the treatment and/or diagnosis of Alzheimer’s disease was proposed, and its results were analyzed with an artificial neural network model. Secondly, the ratio of people suffering from Alzheimer’s disease to the total population, along with data of educational status, income inequality, poverty threshold, and the number of the poor in Turkey were subjected to detailed distribution analysis by using the random forest model statistically. As a result of the study, it was determined that a higher income level was causally associated with a lower risk of Alzheimer’s disease.