Functional brain changes associated with cognitive trajectories determine specific tDCS‐induced effects among older adults

• Published in: Journal of neuroscience research Vol. 99; no. 9; pp. 2188 - 2200
• Main Authors: Vaqué‐Alcázar, Lídia, Abellaneda‐Pérez, Kilian, Solé‐Padullés, Cristina, Bargalló, Núria, Valls‐Pedret, Cinta, Ros, Emilio, Sala‐Llonch, Roser, Bartrés‐Faz, David
• Format: Journal Article
• Language: English
• Published: United States Wiley Subscription Services, Inc 01.09.2021
• Subjects: Adults; Aged; Aging; Brain; Brain - diagnostic imaging; Brain - physiology; Brain mapping; Cognitive ability; Cognitive Dysfunction - diagnostic imaging; Cognitive Dysfunction - physiopathology; Cognitive Dysfunction - therapy; compensation; Cross-Over Studies; Direct current; Electrical stimulation of the brain; ESB; Female; Follow-Up Studies; Functional magnetic resonance imaging; Humans; Longitudinal Studies; Magnetic resonance imaging; Magnetic Resonance Imaging - methods; Magnetic Resonance Imaging - trends; Maintenance; Male; Neuroimaging; Older people; Short term memory; Single-Blind Method; transcranial direct current stimulation; Transcranial Direct Current Stimulation - methods; Transcranial Direct Current Stimulation - trends; working memory; compensation; aging; working memory; maintenance; functional magnetic resonance imaging; transcranial direct current stimulation
• ISSN: 0360-4012; 1097-4547; 1097-4547
• DOI: 10.1002/jnr.24849

The combination of transcranial direct current stimulation (tDCS) with functional magnetic resonance imaging (fMRI) can provide original data to investigate age‐related brain changes. We examined neural activity modulations induced by two multifocal tDCS procedures based on two distinct montages fitting two N‐back task‐based fMRI patterns (“compensatory” and “maintenance”) related to high working memory (WM) in a previous publication (Fernández‐Cabello et al. Neurobiol Aging (2016);48:23–33). We included 24 participants classified as stable or decliners according to their 4‐year WM trajectories following a retrospective longitudinal approach. Then, we studied longitudinal fMRI differences between groups (stable and decliners) and across multifocal tDCS montages (“compensatory” and “maintenance”) applied using a single‐blind sham‐controlled cross‐over design. Decliners evidenced over‐activation of non‐related WM areas after 4 years of follow‐up. Focusing on tDCS effects, among the decliner group, the “compensatory”‐tDCS montage reduced the activity over the posterior regions where these subjects showed longitudinal hyperactivation. These results reinforce the notion that tDCS effects are characterized by an activity reduction and might be more noticeable in compromised systems. Importantly, the data provide novel evidence that cognitive trajectories predict tDCS effects in older adults. Twenty‐four participants were classified as stable or decliners according to their 4‐year working memory (WM) trajectories following a retrospective longitudinal approach. Then, we studied longitudinal functional magnetic resonance imaging (fMRI) differences between groups (stable and decliners) and across two multifocal transcranial direct current stimulation (tDCS) montages (fitting “compensatory” and “maintenance” fMRI patterns related to high WM performance) applied inside the scan using a single‐blind sham‐controlled cross‐over design. Among the decliner group, the “compensatory”‐tDCS montage reduced the activity over the posterior regions where these subjects showed longitudinal hyperactivation.