Two studies hint that circadian dysfunction is a driving force that contributes to Alzheimer’s disease, reports Alzforum.
Daily rhythms are profoundly disturbed in people with AD; indeed, severe insomnia and nighttime activity are a major cause of institutionalization (Harper et al., 2005; Bianchetti et al., 1995). These and other circadian abnormalities, including inactivity during the day, fragmented sleep, and flattened melatonin amplitude, have been extensively described in AD. Autopsies of AD patients have uncovered degeneration of the suprachiasmatic nucleus (SCN), the tiny clutch of neurons sitting above the optic chiasm in the hypothalamus that acts as the central pacemaker for the body’s circadian clock (Zhou et al., 1995).
However, only one study has reported circadian disturbances in mild cognitive impairment, and no one has described whether circadian rhythms falter in people who have brain amyloid without memory problems (Naismith et al., 2013). Ju and colleagues previously reported that sleep quality takes a nosedive when cognitively healthy people have brain amyloid (Apr 2013 conference news), but are other daily cycles disturbed in preclinical AD, as well?