Recent news on sleep

[Rhyothemis]

Some notes on recent research news on sleep, dementia, and cardiovascular disease:

rhyobrain.blogspot.com/2021...

[park_bear]

The study that you referred to: Association of sleep duration in middle and old age with incidence of dementia (2021)

nature.com/articles/s41467-...

Establishes an association, and adjusted for various factors, but did not adjust for Parkinson's which is known to cause both insomnia and dementia.

Association is not necessarily causation.

[Rhyothemis in reply to park_bear]

Correlation vs causation is discussed both the NYT and Guardian article. I have edited to include a bullet point on the article from the Guardian regarding disrupted sleep as a prodromal symptom ( though I had thought that the bullet point under the NYT link implied the existence of the ongoing debate on causality ...)

The association of risk of dementia and poor sleep has been known for some time, the reason the Nature study is news is because it followed people for 25 years and according to the researchers quoted in the NYT article, pathological changes in the brain for AD occur at 15 - 20 years prior to symptoms of dementia.

An alternative explanation that involves shared causality due to dysfunction of the locus coeruleus is offered at the end of my post.

[Rhyothemis in reply to Rhyothemis]

Also edited the NYT bullet point to make the time course aspect more clear.

[Rhyothemis]

another edit to the post; added this to the end:

The following review discusses the role of degeneration of the locus coeruleus in neuroinflammation and pathogenesis of dementia, Alzheimer's and Parkinson's:

Locus Coeruleus Modulates Neuroinflammation in Parkinsonism and Dementia (2020)

pubmed.ncbi.nlm.nih.gov/332...

"Locus Coeruleus (LC) is the main noradrenergic nucleus of the central nervous system, and its neurons widely innervate the whole brain. LC is severely degenerated both in Alzheimer's disease (AD) and in Parkinson's disease (PD), years before the onset of clinical symptoms, through mechanisms that differ among the two disorders.

...

New imaging and biochemical tools have recently been developed in humans to estimate in vivo the integrity of LC, the degree of neuroinflammation, and pathology AD/PD biomarkers; it is auspicable that these will allow in the near future to test the existence of a link between LC-neuroinflammation and neurodegeneration directly in patients."