Browsing by Author "Butler, Christopher"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Splenial white matter integrity is associated with memory impairments in posterior cortical atrophy
    (2021) Overman, Margot Juliette; Zamboni, Giovanna; Butler, Christopher; Ahmed, Samrah
    Posterior cortical atrophy is an atypical form of Alzheimer's disease characterized by visuospatial impairments and predominant tissue loss in the posterior parieto-occipital and temporo-occipital cortex. Whilst episodic memory is traditionally thought to be relatively preserved in posterior cortical atrophy, recent work indicates that memory impairments form a common clinical symptom in the early stages of the disease. Neuroimaging studies suggest that memory dysfunction in posterior cortical atrophy may originate from atrophy and functional hypoconnectivity of parietal cortex. The structural connectivity patterns underpinning these memory impairments, however, have not been investigated. This line of inquiry is of particular interest, as changes in white matter tracts of posterior cortical atrophy patients have been shown to be more extensive than expected based on posterior atrophy of grey matter. In this cross-sectional diffusion tensor imaging MRI study, we examine the relationship between white matter microstructure and verbal episodic memory in posterior cortical atrophy. We assessed episodic memory performance in a group of posterior cortical atrophy patients (n=14) and a group of matched healthy control participants (n=19) using the Free and Cued Selective Reminding Test with Immediate Recall. Diffusion tensor imaging measures were obtained for 13 of the posterior cortical atrophy patients and a second control group of 18 healthy adults. Patients and healthy controls demonstrated similar memory encoding performance, indicating that learning of verbal information was preserved in posterior cortical atrophy. However, retrieval of verbal items was significantly impaired in the patient group compared with control participants. As expected, tract-based spatial statistics analyses showed widespread reductions of white matter integrity in posterior cortical regions of patients compared with healthy adults. Correlation analyses indicated that poor verbal retrieval in the patient group was specifically associated with microstructural damage of the splenium of the corpus callosum. Post-hoc tractography analyses in healthy controls demonstrated that this splenial region was connected to thalamic radiations and the retrolenticular part of the internal capsule. These results provide insight into the brain circuits that underlie memory impairments in posterior cortical atrophy. From a cognitive perspective, we propose that the association between splenial integrity and memory dysfunction could arise indirectly via disruption of attentional processes. We discuss implications for the clinical phenotype and development of therapeutic aids for cognitive impairment in posterior cortical atrophy.
  • No Thumbnail Available
    Item
    The impact of SARS-CoV-2 in dementia across Latin America: A call for an urgent regional plan and coordinated response
    (2020) Ibanez, Agustin; Santamaria-Garcia, Hernando; Guerrero Barragan, Alejandra; Kornhuber, Alexander; Marques Ton, Alyne Mendonca; Slachevsky, Andrea; Lucio Teixeira, Antonio; Mar Meza, Beatriz Marcela; Serrano, Cecilia M.; Cano, Carlos; Arias Gonzalez, Carolina; Gonzalez-Billault, Christian; Butler, Christopher; Bustin, Julian; Duran-Aniotz, Claudia; Acosta, Daisy; Matallana, Diana L.; Acosta-Alvear, Diego; Trepel, Dominic; Franca Resende, Elisa De Paula; Ferreira Oliveira, Fabricio; Ibanez, Francisco; De Felice, Fernanda G.; Navarrete, Gorka; Tarnanas, Ioannis; Meier, Irene B.; Smid, Jerusa; Llibre-Guerra, Jorge; Llibre-Rodriguez, Juan J.; Fajersztajn, Lais; Takada, Leonel Tadao; Duque, Lissette; de Oliveira, Maira Okada; Camargos Bicalho, Maria Aparecida; Isabel Behrens, Maria; Pintado-Caipa, Maritza; Parra, Mario; Wilson, Maxwell Z.; De la Cruz Puebla, Myriam; Custodio, Nilton; Santibanez, Rodrigo; Serafim, Rodrigo Bernardo; Tavares, Ronnielly Melo; Pina Escudero, Stefanie Danielle; Leon Rodriguez, Tomas; Dawson, Walter; Miller, Bruce L.; Kosik, Kenneth S.
    The SARS-CoV-2 global pandemic will disproportionately impact countries with weak economies and vulnerable populations including people with dementia. Latin American and Caribbean countries (LACs) are burdened with unstable economic development, fragile health systems, massive economic disparities, and a high prevalence of dementia. Here, we underscore the selective impact of SARS-CoV-2 on dementia among LACs, the specific strain on health systems devoted to dementia, and the subsequent effect of increasing inequalities among those with dementia in the region. Implementation of best practices for mitigation and containment faces particularly steep challenges in LACs. Based upon our consideration of these issues, we urgently call for a coordinated action plan, including the development of inexpensive mass testing and multilevel regional coordination for dementia care and related actions. Brain health diplomacy should lead to a shared and escalated response across the region, coordinating leadership, and triangulation between governments and international multilateral networks.
  • No Thumbnail Available
    Item
    The Latin America and the Caribbean Consortium on Dementia (LAC-CD): From Networking to Research to Implementation Science
    (2021) Ibanez, Agustin; Parra, Mario A.; Butler, Christopher
    In comparison with other regions, dementia prevalence in Latin America is growing rapidly, along with the consequent clinical, social, and economic burden upon patients and their families. The combination of fragile health care systems, large social inequalities, and isolated clinical and research initiatives makes the coordination of efforts imperative. The Latin America and the Caribbean Consortium on Dementia (LAC-CD) is a regional organization overseeing and promoting clinical and research activities on dementia. Here, we first provide an overview of the consortium, highlighting the antecedents and current mission. Then, we present the consortium's regional research, including the multi-partner consortium to expand dementia research in Latin America (ReDLat), which aims to identify the unique genetic, social, and economic factors that drive Alzheimer's and frontotemporal dementia presentation in LAC relative to the US. We describe an extension of ReDLat which aims to develop affordable markers of disease subtype and severity using high density EEG. We introduce current initiatives promoting regional diagnosis, visibility, and capacity, including the forthcoming launch of the Latin American Brain Health Institute (BrainLat). We discuss LAC-CD-led advances in brain health diplomacy, including an assessment of responses to the impact of COVID-19 on people with dementia and examining the knowledge of public policies among experts in the region. Finally, we present the current knowledge-to-action framework, which paves the way for a future regional action plan. Coordinated actions are crucial to forging strong regional bonds, supporting the implementation of regional dementia plans, improving health systems, and expanding research collaborations across Latin America.