{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"institution":[{"name":"bioRxiv"}],"indexed":{"date-parts":[[2026,5,18]],"date-time":"2026-05-18T09:06:34Z","timestamp":1779095194933,"version":"3.51.4"},"posted":{"date-parts":[[2026,5,14]]},"group-title":"Neuroscience","reference-count":53,"publisher":"openRxiv","license":[{"start":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T00:00:00Z","timestamp":1778716800000},"content-version":"vor","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc-nd\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"accepted":{"date-parts":[[2026,5,14]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                <jats:p>The precise coordination of slow oscillations (SO) and sleep spindles during non-rapid eye movement (NREM) sleep supports memory consolidation and may serve as a sensitive marker of cognitive aging. However, longitudinal changes in their oscillatory dynamics in midlife and older age remain poorly understood. Using polysomnography with high-density EEG at two timepoints over \u223c2.5 years, we examined changes in local NREM slow wave (SW), sleep spindle (occurring in the 11\u201316 Hz sigma range), and SO-sigma coupling strength in cognitively unimpaired middle-aged to older adults at risk for Alzheimer\u2019s disease. Fronto-central SO-sigma power coupling strength significantly declined over time, independent of changes in multiple measures of SW and sleep spindle expression. Local declines in multiple sleep spindle measures were also observed. Greater baseline levels of cerebrospinal fluid (CSF) neurogranin, a postsynaptic protein abundantly expressed in the dendritic spines of the hippocampus and cerebral cortex and implicated in calcium-dependent synaptic plasticity, predicted the magnitude of longitudinal decline in SO-fast sigma coupling strength, which in turn predicted episodic memory performance changes. These findings suggest that longitudinal changes in local sleep oscillatory dynamics are related to decreased synaptic integrity and may serve as an early indicator of memory decline in older adults at risk for Alzheimer\u2019s disease.<\/jats:p>","DOI":"10.64898\/2026.05.11.724419","type":"posted-content","created":{"date-parts":[[2026,5,14]],"date-time":"2026-05-14T19:40:12Z","timestamp":1778787612000},"source":"Crossref","is-referenced-by-count":0,"title":["Longitudinal Alterations in Sleep EEG Biomarkers of Memory Consolidation in Middle-Aged and Older Adults"],"prefix":"10.64898","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-9554-9666","authenticated-orcid":false,"given":"Destiny E.","family":"Berisha","sequence":"first","affiliation":[{"name":"Department of Neurobiology and Behavior, University of California, Irvine, CA, USA"},{"name":"Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Abhishek","family":"Dave","sequence":"additional","affiliation":[{"name":"Department of Cognitive Sciences, University of California, Irvine, CA, USA"},{"name":"Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Negin","family":"Sattari","sequence":"additional","affiliation":[{"name":"Department of Psychiatry and Human Behavior, University of California, Irvine, CA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1349-0507","authenticated-orcid":false,"given":"Miranda G.","family":"Chappel-Farley","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kate E.","family":"Sprecher","sequence":"additional","affiliation":[{"name":"Neuroscience Training Program, University of Wisconsin-Madison, Madison, WI, USA"},{"name":"Department of Medicine, University of Wisconsin-Madison, Madison, WI, USA"},{"name":"Wisconsin Alzheimer\u2019s Disease Research Center, University of Wisconsin\u2013Madison, Madison, WI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jason","family":"Bock","sequence":"additional","affiliation":[{"name":"Department of Neurobiology and Behavior, University of California, Irvine, CA, USA"},{"name":"Center for the Neurobiology of Learning and Memory, University of California, Irvine, CA, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Brady A.","family":"Riedner","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, University of Wisconsin\u2013Madison, Madison, WI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ethan Moran","family":"Grover","sequence":"additional","affiliation":[{"name":"University of Wisconsin-Madison, Madison, WI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Erin M.","family":"Jonaitis","sequence":"additional","affiliation":[{"name":"School of Nursing, University of Wisconsin-Madison, Madison, WI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Henrik","family":"Zetterberg","sequence":"additional","affiliation":[{"name":"Institute of Neuroscience and Physiology, University of Gothenburg, Gothenburg, Sweden"},{"name":"Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, M\u00f6lndal, Sweden"},{"name":"Department of Neurodegenerative Disease, UCL Institute of Neurology, Queen Square, London, UK"},{"name":"UK Dementia Research Institute at UCL, London, UK"},{"name":"Department of Pathology and Laboratory Medicine, University of Wisconsin School of Medicine and Public Health, Madison, WI, USA"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Barbara B.","family":"Bendlin","sequence":"additional","affiliation":[{"name":"Wisconsin Alzheimer\u2019s Disease Research Center, University of Wisconsin\u2013Madison, Madison, WI, USA"},{"name":"Wisconsin Alzheimer\u2019s Institute, Madison, WI, USA"},{"name":"Geriatric Research Education and Clinical Center, Wm. 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