Behavioral and Electrophysiological Correlates of Memory Binding Deficits in Patients at Different Risk Levels for Alzheimer’s Disease

Article type: Research Article

Authors: Pietto, Marcos^{a; b; 1} | Parra, Mario A.^{c; d; e; f; 1} | Trujillo, Natalia^{g; h} | Flores, Facundo^a | García, Adolfo M.^{a; J} | Bustin, Julian^a | Richly, Pablo^a | Manes, Facundo^{a; i} | Lopera, Francisco^h | Ibáñez, Agustín^{a; f; i; 1} | Baez, Sandra^{a; m; *}

Affiliations: [a] Instituto de Neurociencia Cognitiva y Traslacional (INCyT), Laboratorio de Psicología Experimental y Neurociencias (LPEN), Fundación INECO, Universidad de Favaloro, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina | [b] Unidad de Neurobiología Aplicada, Centro de Educación Médica e Investigaciones Clínicas Norberto Quirno (CEMIC), Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Buenos Aires, Argentina | [c] School of Life Sciences, Psychology, Heriot-Watt University, UK | [d] Human Cognitive Neuroscience and Centre for Cognitive Ageing and Cognitive Epidemiology, Department of Psychology, University of Edinburgh, UK | [e] Alzheimer Scotland Dementia Research Centre and Scottish Dementia Clinical Research Network, UK | [f] Universidad Autónoma del Caribe, Barranquilla, Colombia | [g] School of Public Health, University of Antioquia (UDEA), Medellin, Colombia | [h] Neuroscience Group, Faculty of Medicine, University of Antioquia (UDEA), Medellin | [j] Faculty of Elementary and Special Education (FEEyE), National University of Cuyo (UNCuyo), Sobremonte 74, C5500, Mendoza, Argentina | [i] ACR Centre of Excellence in Cognition and its Disorders, Macquarie University, Sydney, Australia | [l] Laboratory of Cognitive Neuroscience, Universidad Adolfo Ibanez, Santiago, Chile | [m] Grupo de Investigación Cerebro y Cognición Social, Bogotá, Colombia

Correspondence: [*] Correspondence to: Sandra Baez, Ph.D., Laboratory of Experimental Psychology & Neuroscience (LPEN), Institute of Cognitive Neurology (INECO) & CONICET, Pacheco de Melo 1860, Buenos Aires, Postal Code 1126, Argentina. Tel./Fax: +54 11 4812 0010; E-mail: sbaez@ineco.org.ar.

Note: [1] These authors contributed equally to this work.

Abstract: Deficits in visual short-term memory (VSTM) binding have been proposed as an early and specific marker for Alzheimer’s disease (AD). However, no studies have explored the neural correlates of this domain in clinical categories involving prodromal stages with different risk levels of conversion to AD. We assessed underlying electrophysiological modulations in patients with mild cognitive impairment (MCI), patients in the MCI stages of familial AD carrying the mutation E280A of the presenilin-1 gene (MCI-FAD), and healthy controls. Moreover, we compared the behavioral performance and neural correlates of both patient groups. Participants completed a change-detection VSTM task assessing recognition of changes between shapes or shape-color bindings, presented in two consecutive arrays (i.e., study and test) while event related potentials (ERPs) were recorded. Changes always occurred in the test array and consisted of new features replacing studied features (shape-only) or features swapping across items (shape-color binding). Both MCI and MCI-FAD patients performed worse than controls in the shape-color binding condition. Early electrophysiological activity (100–250 ms) was significantly reduced in both clinical groups, particularly over fronto-central and parieto-occipital regions. However, shape-color binding performance and their reduced neural correlates were similar between MCI and MCI-FAD. Our results support the validity of the VSTM binding test and their neural correlates in the early detection of AD and highlight the importance of studies comparing samples at different risk for AD conversion. The combined analysis of behavioral and ERP data gleaned with the VSTM binding task can offer a valuable memory biomarker for AD.

Keywords: Electroencephalogram (EEG), event related potentials (ERPs), familial Alzheimer’s disease, memory binding, mild cognitive impairment, short-term memory

DOI: 10.3233/JAD-160056

Journal: Journal of Alzheimer's Disease, vol. 53, no. 4, pp. 1325-1340, 2016