Cited by 185Sleep and Wakefulness ResearchTraumatic Brain Injury and Neurovascular DisturbancesTraumatic Brain Injury Research

The DOI matches its Crossref record; 25 of the 25 references it cites were found in a registry or an index; 16 of the 32 sources its claims cite were checked for support.

Loss of hypocretin (orexin) neurons with traumatic brain injury

Open access

Abstract

Chronic, daytime sleepiness is a major, disabling symptom for many patients with traumatic brain injury (TBI), but thus far, its etiology is not well understood. Extensive loss of the hypothalamic neurons that produce the wake‐promoting neuropeptide hypocretin (orexin) causes the severe sleepiness of narcolepsy, and partial loss of these cells may contribute to the sleepiness of Parkinson disease and other disorders. We have found that the number of hypocretin neurons is significantly reduced in patients with severe TBI. This observation highlights the often overlooked hypothalamic injury in TBI and provides new insights into the causes of chronic sleepiness in patients with TBI. Ann Neurol 2009;66:555–559

Overview

AI snapshot

Written from the paper’s full text.

TL;DR

In postmortem hypothalami from 4 patients with severe TBI versus 4 controls, hypocretin neuron number was significantly reduced by 27%. This suggests that hypothalamic hypocretin neuron loss may contribute to chronic sleepiness after TBI.

Key findings

  • TBI subjects had 27% fewer hypocretin neurons than controls (23,655 ± 5,035 vs. 32,318 ± 3,060 neurons, p = 0.001).
  • MCH neurons were 31% fewer in TBI subjects (39,540 ± 10,900 vs. 57,176 ± 24,016), but this was not quite statistically significant (p = 0.06); excluding one female control with low MCH neuron numbers, TBI subjects had 29% fewer hypocretin neurons (p = 0.002) and 40% fewer MCH neurons (p = 0.003).
  • GFAP-labeled astrocyte density was higher in TBI patients than controls (21 ± 12 vs. 7 ± 2 per mm², p < 0.001), and patients with more severe hypocretin neuron loss had more GFAP-labeled astrocytes (r = −0.46, p = 0.01).
  • TBI hypothalami also showed intense perivascular hypocretin immunoreactivity, and many hypocretin neurons were small and pyknotic with reduced hypocretin fiber density.

Methods

  • Autopsy brains from 4 patients who died 7 to 42 days (mean 19) after severe TBI and 4 control subjects with no clinical evidence of TBI or other neurological disorders; TBI patients were younger (51 ± 19 years) than controls (69 ± 18 years), and all subjects were male except one woman in the control group.
  • Immunohistochemistry for hypocretin-1, MCH, and GFAP; hypocretin and MCH neurons were counted across a 1:24 series of the entire hypothalamus with Abercrombie correction, and GFAP-immunolabeled astrocytes were counted in 30 randomly selected 400 by 400 µm sites within the lateral and posterior hypothalamus.
  • Cell counts were compared between groups using Student’s t-tests.

Limitations

  • Stated by the paper: the study examined a small number of brains, control subjects were not fully matched, other wake-promoting systems were not examined, and the patients had fatal TBI, probably introducing selection bias; non-fatal TBI may be associated with less severe hypocretin neuron loss.
  • Evident from the text: this is described as a pilot study with severe/fatal TBI cases, so findings may not generalize to milder or non-fatal TBI, and the autopsy design cannot directly establish that hypocretin loss causes chronic sleepiness.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1002/ana.21836

Cites

25 of 25 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Verification

Claims the paper makes

11 Own result · 10 Own interpretation · 9 Partly supported · 9 Own method · 7 No full text of the sources · 2 Supported · 1 Sources not found · 1 No basis given · accuracy not yet measured

Show all 22 claims

  • Probably not a substantial claim. 17
  • It may state two separate claims as one. 14
28 of 28
  • The authors state this as an assumption.

    Partial loss of hypocretin neurons causes the generally milder sleepiness of narcolepsy without cataplexy and Parkinson's disease.

    “some hypothesize that a partial loss of these cells causes the generally milder sleepiness of narcolepsy without cataplexy and Parkinson’s disease.14,15,19”
    “This assumption is supported by our recent finding of reduced CSF hypocretin-1 levels in sleepy TBI patients who survived their injury.2”
1 of 1

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

Citations

Cites

Cited by

Sorted by citations

See all 185

Metadata

Authors
Baumann, C. R., Bassetti, C. L., Valko, P. O., Haybaeck, J., Keller, M., Clark, E., Stocker, R., Tolnay, M., & Scammell, T. E.
Affiliations
  • Beth Israel Deaconess Medical Center (US)
  • University Hospital Zurich (CH)
Corresponding author
Baumann, Christian R.
Venue
Annals of Neurology
Publisher
Wiley
Published
2009-10
Volume
66
Issue
4
Pages
555-559
ISSN
  • 0364-5134 (ISSN-L)
  • 1531-8249
OpenAlex
W2025705478
Cited by
185
References
25
Citations by year
2026: 2 · 2025: 8 · 2024: 6 · 2023: 4 · 2022: 13 · 2021: 10 · 2020: 13 · 2019: 11 · 2018: 22 · 2017: 10 · 2016: 10 · 2015: 19 · 2014: 12 · 2013: 10 · 2012: 12
FWCI
5.33
Type
journal article
Language
en
Open access
Locations
  • Annals of Neurology (publishedVersion)
  • PubMed (publishedVersion)
  • Zurich Open Repository and Archive (University of Zurich) (acceptedVersion, other-oa)
  • PubMed Central (submittedVersion)
  • Zurich Open Repository and Archive (University of Zurich) (submittedVersion, other-oa)
  • Zurich Open Repository and Archive (University of Zurich)
Funders
National Institute of Mental Health (R01 MH062589, MH062589)
Topics
  • Life Sciences › Neuroscience › Cognitive Neuroscience › Sleep and Wakefulness Research
  • Health Sciences › Medicine › Clinical Neurology › Traumatic Brain Injury and Neurovascular Disturbances
  • Health Sciences › Medicine › Clinical Neurology › Traumatic Brain Injury Research
Keywords
orexin, traumatic brain injury, hypothalamic neurons, narcolepsy, Parkinson's disease, wakefulness
MeSH terms
Orexins, Adult, Aged, Aged, 80 and over, Brain Injuries, Cell Count, Female, Humans, Hypothalamus, Male, Middle Aged, Neurons, Neuropeptides, Pilot Projects, Wakefulness, Intracellular Signaling Peptides and Proteins

About these checks

Registry, retraction, Cites and statistics results are computed, not judged, with one exception: a printed reference that no index lists is read once by a model before it counts as a citation error. Claims are extracted by a model and kept only when their quote appears verbatim in the text; each cited source is then checked, with a model’s help, for whether it says what the claim relies on. Those verdicts can be wrong — read the claim’s quote and the cited source before relying on one.

A language model drew the claims from the paper on 2026-10-14, under version 3 of the claim definition (model deepseek-v4.1-flash, prompt extract-v3).

A second model labelled each claim on 2026-10-14 (model jev-1.13-20260917, definition revision gold-guideline-v0.2).

Cited sources are checked with a language model’s help (gpt-6-sol).

Statistics and arithmetic are recomputed, not judged.

Confidence bands are shown only for fields calibrated on our annotated test set. None is calibrated yet, so no band is shown.

What counts as a claim ›How we measure confidence ›How we check this ›

Are you an author, or do you see a problem with this page? Request a review