Sleep and Dementia
Anyone who makes a living in the knowledge business, or who just simply enjoys the life of the mind, worries about the eventual prospect of dementia. Alzheimer’s and related diseases are relentless, irreversible, and anxiety producing.
One antidote to anxiety is sleep: we don’t fret about Alzheimer’s, or much of anything, when blissfully snoozing. And sleeping it off works pretty well for banishing assorted worries.
New research from Washington University suggests the two may be related. A major molecular culprit in Alzheimer’s is accumulation in the brain of amyloid-β, which eventually coalesces into the damaging fibrils characteristic of the disease.
Kang et al. asked whether amyloid-β concentrations in the brain were linked to sleep-wake cycles (Science 326: 5955 [13 November 2009], 1005–1007). The result is that chronic sleep restriction significantly increases both amyloid-β and plaque formation in mice. A nifty control experiment showed that the change is due to sleep cycles rather than light/dark variations.
Just in case you aren’t too worried about dementia in mice, the result also shows up in human volunteers. And a small molecule (0rexin) that regulates wakefulness by binding to receptors in the hippocampus mimicked sleep deprivation’s effects on amyloid-β.
Getting a good night’s sleep is looking better and better. Come to think of it, a nap sounds pretty good right now.