Circadian Dysfunction May ID Preclinical Alzheimer's

A study published in JAMA Neurology revealed an association between amyloid plaque pathology, assessed by cerebrospinal fluid biomarkers or positron emission tomography amyloid imaging, with circadian disruptions in cognitively normal adults even after accounting for effects of aging and gender, reports MedPage Today . "We found that fragmentation of the circadian rhythm ... was associated with preclinical Alzheimer's disease," says Yo-El S. Ju with the Washington University School of Medicine. The team examined 189 cognitively normal volunteers from the Knight Alzheimer's Disease Research Center from 2010 through 2012. Participants were mostly female, about 67 years old on average, and highly educated. Seventy-four percent of the volunteers were amyloid negative while those who were Pittsburgh Compound B (PiB)-positive were older. Lacking amyloid pathology, older age and male gender were associated with a significant elevation in rest-activity fragmentation and decreased circadian rhythm amplitude. Following adjustment for age and sex, PiB-positive individuals had more circadian fragmentation than PiB-negative participants. "Altogether, our data suggest that aging and preclinical AD pathology have separate and additive negative effects on circadian rhythm fragmentation," the researchers note. Also detected was a significant correlation between the number of naps participants took and circadian fragmentation, suggesting disrupted daytime rest-activity patterns might be a sign of presymptomatic Alzheimer's.