{
  "id": 4881044,
  "title": "The circadian system is affected by Alzheimers disease independently from amyloid beta deposits",
  "url": "https://urgent.news/2026/09/01/the-circadian-system-is-affected-by-alzheimers-disease-independently",
  "topic": "health",
  "section": "Health & Medicine",
  "published": "2026-09-01T00:00:00.000Z",
  "source": {
    "name": "bioRxiv",
    "slug": "biorxiv",
    "url": "https://www.biorxiv.org/content/10.64898/2026.08.25.744599v1?rss=1"
  },
  "original_language": "en",
  "account": "Alzheimer's disease (AD) disrupts the circadian system, leading to sleep disturbances even before cognitive symptoms arise. The suprachiasmatic nucleus (SCN), responsible for regulating biological rhythms, receives direct retinal input to align with environmental light cycles. However, the underlying mechanisms of circadian disruption in AD remain unclear. To investigate this, researchers examined the APP/PS1 mouse model, observing significant reductions in rapid eye movement (REM) sleep and altered daily core body temperature amplitude. Additionally, APP/PS1 mice displayed hyperactivity at a young age and hypoactivity at older ages, functions typically regulated by the SCN. Serial blockface electron microscopy revealed a reduction in the dendro-dendritic chemical synapse network, crucial for synchronizing SCN neurons. Dendritic morphology alterations, lysosome accumulation, and axonal swelling were also observed. Spatial transcriptomics analysis of the SCN highlighted changes in gene expression related to synapse formation, cell adhesion, and neurite growth. These findings suggest that the SCN of APP/PS1 mice undergo significant gene expression changes, impacting connectomics and physiological functions, despite the absence of amyloid plaques in the ventral hypothalamus.",
  "summary": "Circadian disruption, notably sleep disturbances, serves as an early indicator of Alzheimers disease (AD), preceding cognitive symptoms like memory loss. The suprachiasmatic nucleus (SCN) governs biological rhythms and receives direct retinal input via melanopsin-expressing retinal ganglion cells (mRGCs) to synchronize with environmental light cycles. The anatomical and functional basis for…",
  "key_points": [],
  "editors_take": null,
  "illustration": null,
  "coverage": {
    "outlets": 1,
    "also_reported_by": []
  },
  "ai_generated": true,
  "disclaimer": "Summaries, key points and the editor’s take are written by software from other outlets’ reporting and may contain errors — always check the linked original."
}