Prospective memory impairments in Alzheimer's Disease and behavioral variant frontotemporal dementia: Clinical and neural correlates

BACKGROUND: Prospective memory (PM) refers to a future-oriented form of memory in which the individual must remember to execute an intended action either at a future point in time (Time-based) or in response to a specific event (Event-based). Lapses in PM are commonly exhibited in neurodegenerative disorders including Alzheimer's disease (AD) and frontotemporal dementia (FTD), however, the neurocognitive mechanisms driving these deficits remain unknown. OBJECTIVE: To investigate the clinical and neural correlates of Time- and Event-based PM disruption in AD and the behavioral-variant FTD (bvFTD). METHODS: Twelve AD, 12 bvFTD, and 12 healthy older Control participants completed a modified version of the Cambridge Prospective Memory test, which examines Time- and Event-based aspects of PM. All participants completed a standard neuropsychological assessment and underwent whole-brain structural MRI. RESULTS: AD and bvFTD patients displayed striking impairments across Time- and Event-based PM relative to Controls, however, Time-based PM was disproportionately affected in the AD group. Episodic memory dysfunction and hippocampal atrophy was found to correlate strongly with PM integrity in both patient groups, however, dissociable neural substrates were also evident for PM performance across dementia syndromes. CONCLUSION: Our study reveals the multifaceted nature of PM dysfunction in neurodegenerative disorders, and suggests common and dissociable neurocognitive mechanisms, which subtend these deficits in each patient group. Future studies of PM disturbance in dementia syndromes will be crucial for the development of successful interventions to improve functional independence in the patient's daily life

“Other” possibilities? Assessing regional and extra-regional dental affinities of populations in the Portuguese Estremadura to explore the roots of Iberia’s Late Neolithic-Copper Age

The relationship between the development of social complexity in the Iberian Peninsula during the 4th and 3rd millennia BCE (Late Neolithic and Copper Age) and population movement has been a longstanding question. Biological affinity analyses were used to explore Iberian demographic dynamics, and specifically, to discern whether there is evidence for migration and gene flow between northwest African, eastern Mediterranean, and Iberian populations. Affinities based on comparisons of nonmetric traits from the Arizona State University Dental Anthropology System were estimated among samples of burial populations from three key Late Neolithic-Copper Age sites in the Portuguese Estremadura: Cova da Moura (3700-2300 BCE), Bolores (2800-2600 BCE), and Pai Mogo I (2800-2600 BCE). Results indicate: 1) the possibility of genetic exchange with African and other Mediterranean peoples, 2) some measure of population continuity over time in the Estremadura, and 3) possible local isolation of populations, given distinctive patterning at the site of Pai Mogo, located 23 km north of Cova da Moura and Bolores

Behavioral inferences from the high levels of dental chipping in Homo naledi

Objectives: A variety of mechanical processes can result in ante-mortem dental chipping. In this study, chipping data in the teeth of Homo naledi are compared with those of other pertinent dental samples to give insight into their etiology. Materials and Methods: Permanent teeth with complete crowns evidencing occlusal wear were examined macroscopically. The location, number, and severity of fractures were recorded and compared to those found in samples of two other South African fossil hominin species, as well as in samples of non-human primates (n= 3) and recent humans (n= 7). Results: With 44% of teeth affected, Homo naledi exhibits far higher rates of chipping than the other fossil hominin samples. Specifically, 50% of posterior teeth and 31% of anterior teeth display at least one chip. The maxillary teeth are more affected than the mandibular teeth (45% vs. 43%, respectively), 73% of molar chipping occurs on interproximal surfaces, and right teeth are more often affected than left teeth (50% vs. 38%). Discussion: Results indicate that the teeth of H. naledi were exposed to acute trauma on a regular basis. Because interproximal areas are more affected than buccal, and posterior teeth more than anterior, it is unlikely that non-masticatory cultural behavior was the cause. A diet containing hard and resistant food, or contaminants such as grit, is more likely. The small chip size, as well as steep occlusal wear and cupped dentine on some molars is supportive of the latter possibility. This pattern of chipping suggests H. naledi differed considerably – in terms of diet, environment, and/or specialized masticatory processing— relative to other African fossil hominins

Root grooves on two adjacent anterior teeth of Australopithecus africanus

Tooth root grooves and other ante-mortem dental tissue loss, not associated with caries found on or near the cementoenamel junction (CEJ), are commonly termed non-carious cervical lesions. Three main processes are implicated in forming these lesions: abrasion, dental erosion, and abfraction. As yet, these lesions have not been described in non-Homo hominins. In this study, South African fossil hominin collections were examined for evidence of any type of non-carious cervical lesion. Only one individual shows ante-mortem root grooves consistent with non-carious cervical lesions. Two teeth, a mandibular right permanent lateral incisor (STW 270) and canine (STW 213), belonging to the same Australopithecus africanus individual, show clear ante-mortem grooves on the labial root surface. These lesions start below the CEJ, extend over a third of the way toward the apex, and taper to a point towards the lingual side. The characteristics of these grooves suggest the predominant aetiology was erosive wear. In addition, they are extremely similar to clinical examples of dental erosion. These are the oldest hominin examples of non-carious cervical lesions and the first described in a genus other than Homo. Further, the lesions suggest that this individual regularly processed and consumed acidic food items. © 2018 Elsevier Inc

Scene construction impairments in Alzheimer's disease – A unique role for the posterior cingulate cortex

Episodic memory dysfunction represents one of the most prominent and characteristic clinical features of patients with Alzheimer's disease (AD), attributable to the degeneration of medial temporal and posterior parietal regions of the brain. Recent studies have demonstrated marked impairments in the ability to envisage personally relevant events in the future in AD. It remains unclear, however, whether AD patients can imagine fictitious scenes free from temporal constraints, a process that is proposed to rely fundamentally upon the integrity of the hippocampus. The objective of the present study was to investigate the capacity for atemporal scene construction, and its associated neural substrates, in AD. Fourteen AD patients were tested on the scene construction task and their performance was contrasted with 14 age- and education-matched healthy older Control participants. Scene construction performance was strikingly compromised in the AD group, with significant impairments evident for provision of contextual details, spatial coherence, and the overall richness of the imagined experience. Voxel-based morphometry analyses based on structural MRI revealed significant associations between scene construction capacity and atrophy in posterior parietal and lateral temporal brain structures in AD. In contrast, scene construction performance in Controls was related to integrity of frontal, parietal, and medial temporal structures, including the parahippocampal gyrus and posterior hippocampus. The posterior cingulate cortex (PCC) emerged as the common region implicated for scene construction performance across participant groups. Our study highlights the importance of regions specialised for spatial and contextual processing for the construction of atemporal scenes. Damage to these regions in AD compromises the ability to construct novel scenes, leading to the recapitulation of content from previously experienced events

News and views: Response to 'Non-metric dental traits and hominin phylogeny' by Carter et al., with additional information on the Arizona State University Dental Anthropology System and phylogenetic 'place' of Australopithecus sediba

Here we respond to Carter and colleagues’ (2013) remarks concerning our Science article (Irish et al., 2013). The goals for that article were to: 1) further characterize Australopithecus sediba by describing 22 Arizona State University Dental Anthropology System (ASUDAS) traits, 2) compare the traits in A. sediba with those previously recorded in other hominin samples, and 3) present initial phylogenetic analyses using these data. Given the subset of traits, out of 125 possible (below), and small A. sediba sample, our conclusion was that the results “further define [the species’] position relative to other genera,” but that “the phylogenetic place of A. sediba has not been settled” (Irish et al., 2013: 1233062–12330624). These goals were met, as a basis for more comprehensive study. Below we summarize and reply to the eight objections of Carter et al. (2013), while: 1) demonstrating that there is a strong theoretical basis for using the ASUDAS in phylogenetic analyses, 2) presenting results (which corroborate previous cladistic analyses) that are congruent using different methodological approaches, and 3) introducing new results using a second outgroup, Pan troglodytes, that fully uphold our original analysis

Lost in spatial translation - A novel tool to objectively assess spatial disorientation in Alzheimer's disease and frontotemporal dementia

Spatial disorientation is a prominent feature of early Alzheimer's disease (AD) attributed to degeneration of medial temporal and parietal brain regions, including the retrosplenial cortex (RSC). By contrast, frontotemporal dementia (FTD) syndromes show generally intact spatial orientation at presentation. However, currently no clinical tasks are routinely administered to objectively assess spatial orientation in these neurodegenerative conditions. In this study we investigated spatial orientation in 58 dementia patients and 23 healthy controls using a novel virtual supermarket task as well as voxel-based morphometry (VBM). We compared performance on this task with visual and verbal memory function, which has traditionally been used to discriminate between AD and FTD. Participants viewed a series of videos from a first person perspective travelling through a virtual supermarket and were required to maintain orientation to a starting location. Analyses revealed significantly impaired spatial orientation in AD, compared to FTD patient groups. Spatial orientation performance was found to discriminate AD and FTD patient groups to a very high degree at presentation. More importantly, integrity of the RSC was identified as a key neural correlate of orientation performance. These findings confirm the notion that i) it is feasible to assess spatial orientation objectively via our novel Supermarket task; ii) impaired orientation is a prominent feature that can be applied clinically to discriminate between AD and FTD and iii) the RSC emerges as a critical biomarker to assess spatial orientation deficits in these neurodegenerative conditions

Balloons

This was the earliest Robbie had been awake in five weeks. In the corner of the lively Surry Hills café—his sister’s choice—he sat, waiting at a two-seater. He sipped warm water, poured from a dirty bottle. He overheard conversations.Scholarships & Prizes Office. University of Sydne

The lived experiences of nuclear medicine technologists during Covid-19 pandemic

This study presented the lived experiences of the nuclear medicine technologists (NMTs) during the COVID-19 pandemic. The participants of this study are nuclear medicine technologists working in healthcare facilities before and during the COVID-19 pandemic. A qualitative research design was used, specifically the phenomenological qualitative approach. The participants were chosen through purposive and snowball sampling. Based on the findings, it can be concluded that the experiences of the NMTs is an interplay of fear, sadness, and happiness. Fear of contacting COVID and/or spreading it to others has become a driving force to be more mindful of the infection control measures, specifically on the use of PPEs and appropriate physical distancing measures. The sadness, happiness, and fear felt by the participants have seemed to balance and helped the participants to cope with the pandemic. There had been notable changes in the personal-social (isolation from family and friends) and professional (workload change, redeployment) lives of the participants. Adaptation to the changes brought about by the pandemic has been evident in the participants. These reflect the resilience of the participants in the midst of the pandemi