A Brief Drawing Task for the Differential Diagnosis of Semantic Dementia

Drawing from name in semantic dementia reveals graded object knowledge representations in anterior temporal lobe

Semantic dementia (SD) is characterized by progressive impairment in conceptual knowledge due to anterior temporal lobe (ATL) neurodegeneration. Extended neuropsychological assessments can quantitatively demonstrate the semantic impairment, but this graded loss of knowledge can also be readily observed in the qualitative observation of patients' recall of single concepts. Here, we present the results of a simple task of object drawing-from-name, by patients with SD (N = 19), who have isolated atrophy of the ATL bilaterally. Both cross-sectionally and longitudinally, patient drawings demonstrated a pattern of degradation in which rare and distinctive features (such as the hump on a camel) were lost earliest in disease course, and there was an increase in the intrusion of prototypical features (such as the typical small ears of most mammals on an elephant) with more advanced disease. Crucially, patient drawings showed a continuum of conceptual knowledge loss rather than a binary 'present' or 'absent' state. Overall, we demonstrate that qualitative evaluation of line drawings of animals and objects provides fascinating insights into the transmodal semantic deficit in SD. Our results are consistent with a distributed-plus-hub model of semantic memory. The graded nature of the deficit in semantic performance observed in our subset of longitudinally observed patients suggests that the temporal lobe binds feature-based semantic attributes in its central convergence zone.

Age-related hearing loss is not linked to cerebrospinal fluid levels of β-amyloid or p-tau181

INTRODUCTION

As Hearing loss and dementia affect people with the same profile, several epidemiological studies have evaluated their relationship. However, the link between age-related hearing loss and Alzheimer's disease is still unclear.

METHODS

We selected subjects with no history of exposure to loud noises, blasts, head trauma with hearing loss, or sudden sensorineural hearing loss from a cohort intended to study preclinical phases of Alzheimer's disease. Participants are volunteers over 55 years without cognitive impairment. We correlated the results of an objective auditory evaluation with brain amyloid and p-tau181 levels and with the outcomes of a comprehensive neuropsychological assessment.

RESULTS

Fifty-five subjects at different stages of the Alzheimer's disease continuum were evaluated. There were no statistically significant correlations between amyloid-β and p-tau levels and any of the objective auditory measures. A weak but significant correlation was found between amyloid-β values and the Hearing Handicap Inventory for the Elderly. The neuropsychological domains more correlated to hearing loss were executive function and processing speed.

DISCUSSION

Age-related hearing loss is not linked to any pathological markers of Alzheimer's disease nor to neuropsychological domains typically affected in this disease. The Hearing Handicap Inventory for the Elderly has an important component of subjectivity and further studies are needed to explore its relationship with amyloid-β levels.

"This looks like a movie": a case report of post-surgical amnesia

A 52-year-old male patient with a background of adaptive personality disorder was admitted for mitral valve repair and cardiac ablation for atrial fibrillation. He suffered intraoperative complications with severe mitral insufficiency that suffered ischemia.. Post-operatively, he demonstrated acute loss of retrograde autobiographical memory, prosopagnosia and a loss of public semantic memory. His CT scan was normal and MRI was not possible due to intra-cardiac leads. An initial diagnosis of hypoxic-ischemic encephalopathy was considered. A neuropsychological examination undertaken 20 days after his surgery showed a severe alteration of retrograde autobiographical memory, marked alteration of semantic knowledge and prosopagnosia. He demonstrated an average performance in tasks measuring constructional praxis, visuospatial ability, and executive functions. 34 days after surgery, and after a short nap, the patient "returns" to the day before admission and consequently recovers his memory. Repeat neuropsychological assessment demonstrated performance within the normal range across all previously tested domains. This sudden recovery of memory, together with a normal MRI, led to a rethinking of the diagnosis of dissociative amnesia. This case illustrates the long-standing discussion about the organic or functional origin of some memory disorders, in which, despite advances in neuroimaging techniques, it is still difficult to know their etiology    .

Frontotemporal dementia: A unique window on the functional role of the temporal lobes

Frontotemporal dementia (FTD) is an umbrella term covering a plethora of progressive changes in executive functions, motor abilities, behavior, and/or language. Different clinical syndromes have been described in relation to localized atrophy, informing on the functional networks that underlie these specific cognitive, emotional, and behavioral processes. These functional declines are linked with the underlying neurodegeneration of frontal and/or temporal lobes due to diverse molecular pathologies. Initially, the accumulation of misfolded proteins targets specifically susceptible cell assemblies, leading to relatively focal neurodegeneration that later spreads throughout large-scale cortical networks. Here, we discuss the most recent clinical, neuropathological, imaging, and genetics findings in FTD-spectrum syndromes affecting the temporal lobe. We focus on the semantic variant of primary progressive aphasia and its mirror image, the right temporal variant of FTD. Incipient focal atrophy of the left anterior temporal lobe (ATL) manifests with predominant naming, word comprehension, reading, and object semantic deficits, while cases of predominantly right ATL atrophy present with impairments of socioemotional, nonverbal semantic, and person-specific knowledge. Overall, the observations in FTD allow for crucial clinical-anatomic inferences, shedding light on the role of the temporal lobes in both cognition and complex behaviors. The concerted activity of both ATLs is critical to ensure that percepts are translated into concepts, yet important hemispheric differences should be acknowledged. On one hand, the left ATL attributes meaning to linguistic, external stimuli, thus supporting goal-oriented, action-related behaviors (e.g., integrating sounds and letters into words). On the other hand, the right ATL assigns meaning to emotional, visceral stimuli, thus guiding socially relevant behaviors (e.g., integrating body sensations into feelings of familiarity).

Language in Behavioral Variant Frontotemporal Dementia: Another Stone to Be Turned in Latin America

Beyond canonical deficits in social cognition and interpersonal conduct, behavioral variant frontotemporal dementia (bvFTD) involves language difficulties in a substantial proportion of cases. However, since most evidence comes from high-income countries, the scope and relevance of language deficits in Latin American bvFTD samples remain poorly understood. As a first step toward reversing this scenario, we review studies reporting language measures in Latin American bvFTD cohorts relative to other groups. We identified 24 papers meeting systematic criteria, mainly targeting phonemic and semantic fluency, naming, semantic processing, and comprehension skills. The evidence shows widespread impairments in these domains, often related to overall cognitive disturbances. Some of these deficits may be as severe as in other diseases where they are more widely acknowledged, such as Alzheimer's disease. Considering the prevalence and informativeness of language deficits in bvFTD patients from other world regions, the need arises for more systematic research in Latin America, ideally spanning multiple domains, in diverse languages and dialects, with validated batteries. We outline key challenges and pathways of progress in this direction, laying the ground for a new regional research agenda on the disorder.

Nonverbal Semantics Test (NVST)-A Novel Diagnostic Tool to Assess Semantic Processing Deficits: Application to Persons with Aphasia after Cerebrovascular Accident

Assessment of semantic processing capacities often relies on verbal tasks which are, however, sensitive to impairments at several language processing levels. Especially for persons with aphasia there is a strong need for a tool that measures semantic processing skills independent of verbal abilities. Furthermore, in order to assess a patient’s potential for using alternative means of communication in cases of severe aphasia, semantic processing should be assessed in different nonverbal conditions. The Nonverbal Semantics Test (NVST) is a tool that captures semantic processing capacities through three tasks—Semantic Sorting, Drawing, and Pantomime. The main aim of the current study was to investigate the relationship between the NVST and measures of standard neurolinguistic assessment. Fifty-one persons with aphasia caused by left hemisphere brain damage were administered the NVST as well as the Aachen Aphasia Test (AAT). A principal component analysis (PCA) was conducted across all AAT and NVST subtests. The analysis resulted in a two-factor model that captured 69% of the variance of the original data, with all linguistic tasks loading high on one factor and the NVST subtests loading high on the other. These findings suggest that nonverbal tasks assessing semantic processing capacities should be administered alongside standard neurolinguistic aphasia tests.

A snake that bites its own tail. Acquisition and loss of concepts in children and semantic dementia patients through the analysis of drawings

OBJECTIVE

The structure of the semantic network is constructed and organized during childhood development. Previous publications have hypothesized that neurodegenerative diseases would lead to a disruption of this network reversing the steps acquired in childhood. Semantic Dementia (SD) is a subtype of frontotemporal lobe degeneration in which the main symptom is a specific loss of semantic memory. We aimed to describe the sequential acquisition of concepts in 3-8 years old children evaluated through the production of drawings and, in parallel, their progressive loss in SD patients.

METHODS

104 children between 40 and 96 months categorized into tertiles according to their age, 21 SD patients categorized into tertiles according to their score on a category fluency task and 34 healthy volunteers were asked to draw 12 items with, a priori, different age of acquisition and familiarity, belonging to four different semantic categories. We employed the drawings of the healthy volunteers to build a scoring scheme. We considered that a concept was acquired in children when 50% or more of its features were present in their drawings, and it was lost in patients when more than 50% were missing.

RESULTS

Those concepts which the children were able to acquire earlier, according to our scoring scheme, tended to remain in patients with more advanced SD. While the items that children acquired later, were, in general, those that the SD patients lost at earlier disease stages.

CONCLUSION

The patterns of concept acquisition in children were the mirror image of the loss in patients with SD. Our study supports the hypothesis that the sequence of concept acquisition in childhood is reversed in SD patients.