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In healthy elderly, both montages improved performance with load-dependent effects; frontal stimulation notably benefited accuracy and reaction time in the 3-back task. In the MCI group, stimulation effects were weaker and not robust, with only marginal improvements in a transfer task. Benefits varied by load and montage, indicating potentially different optimal parameters for each population.",{"@graph":14,"@context":73},[15,34,56],{"@type":16,"itemListElement":17},"BreadcrumbList",[18,23,27,31],{"item":19,"name":20,"@type":21,"position":22},"https://docshare.wps.com","Home","ListItem",1,{"item":24,"name":25,"@type":21,"position":26},"https://docshare.wps.com/document/","Document",2,{"item":28,"name":29,"@type":21,"position":30},"https://docshare.wps.com/document/healthcare/","Healthcare",3,{"item":32,"name":10,"@type":21,"position":33},"https://docshare.wps.com/document/optimizing-tacs-for-working-memory-differential-outcomes-in-healthy-aging-and-non-amnestic-mild-cognitive-impairment/455839/",4,{"url":32,"name":10,"@type":35,"image":36,"author":41,"headline":10,"publisher":44,"fileFormat":47,"inLanguage":8,"description":12,"dateModified":48,"datePublished":49,"encodingFormat":47,"isAccessibleForFree":50,"interactionStatistic":51},"DigitalDocument",{"url":37,"@type":38,"width":39,"height":40},"https://docshare.wps.com/thumbnails/optimizing-tacs-for-working-memory-differential-outcomes-in-healthy-aging-and-non-amnestic-mild-cognitive-impairment/455839.png","ImageObject",300,407,{"name":42,"@type":43},"Kyle","Person",{"url":19,"name":45,"@type":46},"DocShare","Organization","application/pdf","2026-11-06","2026-09-30",true,{"@type":52,"interactionType":53,"userInteractionCount":55},"InteractionCounter",{"@type":54},"ViewAction",13,{"@type":57,"mainEntity":58},"FAQPage",[59,65,69],{"name":60,"@type":61,"acceptedAnswer":62},"What brain stimulation approach was tested in this study?","Question",{"text":63,"@type":64},"The study applied theta-frequency transcranial alternating current stimulation (tACS) either monofocally over the frontal site or bifocally over frontal and parietal sites.","Answer",{"name":66,"@type":61,"acceptedAnswer":67},"How were working memory outcomes measured?",{"text":68,"@type":64},"Working memory was assessed with 2-back and 3-back tasks performed during and after each stimulation session, plus a letter 2-back transfer task.",{"name":70,"@type":61,"acceptedAnswer":71},"Did theta tACS improve working memory similarly in healthy elderly and non-amnestic MCI?",{"text":72,"@type":64},"Improvements were stronger in the healthy elderly group, while the non-amnestic MCI group showed weaker, non-robust effects despite lower baseline performance.","https://schema.org",{"og:url":32,"og:type":75,"og:title":10,"og:site_name":45,"og:description":12},"article",{"robots":77,"canonical":32},"index,follow",{"doc_id":79,"site_id":7},455839,1790792608,{"code":4,"msg":82,"data":83},"success",[84,88,92,96,101,106,110,115,120,123,127],{"id":22,"doc_module":4,"doc_module_name":25,"category_name":85,"show_sort_weight":86,"slug":87},"Story & Novel",90,"story-novel",{"id":26,"doc_module":4,"doc_module_name":25,"category_name":89,"show_sort_weight":90,"slug":91},"Literature",80,"literature",{"id":33,"doc_module":4,"doc_module_name":25,"category_name":93,"show_sort_weight":94,"slug":95},"Exam",70,"exam",{"id":97,"doc_module":4,"doc_module_name":25,"category_name":98,"show_sort_weight":99,"slug":100},5,"Comic",60,"comic",{"id":102,"doc_module":4,"doc_module_name":25,"category_name":103,"show_sort_weight":104,"slug":105},6,"Technology",50,"technology",{"id":107,"doc_module":4,"doc_module_name":25,"category_name":29,"show_sort_weight":108,"slug":109},7,40,"healthcare",{"id":111,"doc_module":4,"doc_module_name":25,"category_name":112,"show_sort_weight":113,"slug":114},8,"Research & Report",30,"research-report",{"id":116,"doc_module":4,"doc_module_name":25,"category_name":117,"show_sort_weight":118,"slug":119},9,"Religion & Spirituality",20,"religion-spirituality",{"id":118,"doc_module":4,"doc_module_name":25,"category_name":121,"show_sort_weight":118,"slug":122},"World Cup","world-cup",{"id":124,"doc_module":4,"doc_module_name":25,"category_name":125,"show_sort_weight":124,"slug":126},10,"Lifestyle","lifestyle",{"id":128,"doc_module":4,"doc_module_name":25,"category_name":129,"show_sort_weight":97,"slug":130},19,"General","general",{"code":4,"msg":82,"data":132},{"doc_id":79,"user_id":133,"nickname":42,"user_avatar":134,"doc_module":4,"category_id":107,"category_name":29,"doc_title":10,"doc_description":12,"doc_content":135,"file_id":136,"file_url":137,"file_type":138,"file_size":139,"view_count":55,"is_deleted":4,"is_public":22,"is_downloadable":22,"audit_status":22,"page_count":140,"language":141,"language_code":8,"site_id":7,"html_lang":8,"table_of_contents":142,"faqs":143,"seo_title":144,"seo_description":12,"update_tm":145,"read_time":113,"preview_page_count":4},3985741905716,"https://ap-avatar.wpscdn.com/davatar_994ba38a5ba835b3df7d355c54d3ed8d","Mitterová et al. Alzheimer's Research & Therapy (2026) 18:2 [https://doi.org/10.1186/s13195-025-01922-4](https://doi.org/10.1186/s13195-025-01922-4)  \nAlzheimer's Research & Therapy  \nRESEARCH Open Access  \nOptimizing tACS for working memory: differential outcomes in healthy aging and non-amnestic mild cognitive impairment  \nKristína Mitterová 1, Monika Pupíková 1, Martin Gajdoš2, Ilona Eliášová3 and Irena Rektorová 1,3*  \nAbstract  \nTranscranial alternating current stimulation (tACS) in the theta frequency range has been shown to enhance working memory (WM) performance. However, no studies have directly compared the effects of theta tACS between cognitively healthy elderly (HE) subjects and subjects with non-amnestic mild cognitive impairment (MCI) . Our proof–of-concept study investigated the effects of monofocal (frontal) and bifocal (frontoparietal) theta tACSon WM in two cognitive loads in HE subjects and in subjects with MCI. In this sham-controlled, single-blinded, repeated-measures study with counterbalanced stimulation order across subjects (n = 55), theta tACS (4 .51 Hz,  \n1.5 mA, 20 min) was applied either over the frontal site alone or simultaneously over frontal and parietal sites. WM 2-back and 3-back tasks were performed during and after each stimulation session. In the HE group, both frontal and frontoparietal stimulations improved performance, albeit with load-dependent differences. Frontal stimulation was particularly effective in the higher cognitive load, enhancing accuracy (β = -3 . 87; p = . 033) and reaction times (β = − . 042; p = . 002) in the 3-back task. Frontoparietal stimulation improved accuracy (β = -3 . 74; p = . 027) but not reaction time (p > . 22) in the 2-back task in the HE group. Frontoparietal stimulation enhanced accuracy in the 3-back task across all participants (β = 1 . 91; p = . 043) . In the MCI group, frontal stimulation led to faster reaction times in the 3-back task, although the effects were not robust. Lastly, a marginally significant improvement in reaction times was observed in a letter 2-back transfer task following frontal stimulation (β = − . 034; p \u003C . 092) across all participants. Our findings indicate that theta tACS over the frontal and frontoparietal areas elicits benefits in WM performance, driven mainly by enhancements in HE subjects. The effects of stimulation varied with cognitive load and montage, suggesting that optimal stimulation parameters may differ depending on task demands. The nonamnestic MCI group did not exhibit greater improvements despite their lower baseline performance, possibly due to higher variability in pathology and compensation. Multiple sessions or alternative stimulation parameters maybe needed to achieve robust effects in subjects with MCI. The study was retrospectively registered on ClinicalTrials. gov (NCT06563453) .  \nKeywords TACS, Non-invasive brain stimulation, n-back task, Theta stimulation, Working memory, Healthy elderly, MCI  \n*Correspondence:  \nIrena Rektorová  \n[irena. rektorova@fnusa.cz](irena. rektorova@fnusa.cz)  \n1Applied Neuroscience Research Group, Brain and Mind Research Programme, Central European Institute of Technology, Masaryk University, Pekarska 53, Brno 656 91, Czechia  \n2Multimodal and Functional Imaging Laboratory, Brain and Mind Research Programme, Central European Institute of Technology, Masaryk University, Brno, Czechia  \n3First Department of Neurology, St. Anne’s University Hospital and Faculty of Medicine, Masaryk University, Brno, Czechia  \n© The Author(s) 2025. Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creat","cbCaiknkT4KnA1vq","https://ap.wps.com/l/cbCaiknkT4KnA1vq","pdf",10966051,12,"English","# Abstract\n## Background\n## Correspondence and Affiliations\n## Licensing and Access","[{\"question\":\"What brain stimulation approach was tested in this study?\",\"answer\":\"The study applied theta-frequency transcranial alternating current stimulation (tACS) either monofocally over the frontal site or bifocally over frontal and parietal sites.\"},{\"question\":\"How were working memory outcomes measured?\",\"answer\":\"Working memory was assessed with 2-back and 3-back tasks performed during and after each stimulation session, plus a letter 2-back transfer task.\"},{\"question\":\"Did theta tACS improve working memory similarly in healthy elderly and non-amnestic MCI?\",\"answer\":\"Improvements were stronger in the healthy elderly group, while the non-amnestic MCI group showed weaker, non-robust effects despite lower baseline performance.\"}]","Optimizing tACS for working memory - differential outcomes in healthy aging and non-amnestic mild cognitive impairment | PDF",1790744454]