THURSDAY, March 14 (HealthDay News) -- Sleep quality is associated with β-amyloid (Aβ) deposition among older adults; and Aβ oligomers are associated with tau prior to onset of overt symptoms of Alzheimer's disease, according to two studies published online March 11 in JAMA Neurology.
Yo-El S. Ju, M.D., from the Washington University School of Medicine in St. Louis, and colleagues conducted a cross-sectional study involving 142 cognitively normal individuals, aged 45 years and older, with valid actigraphy data, to examine whether Aβ deposition in preclinical Alzheimer's disease is associated with changes in sleep quality or quantity. The researchers identified amyloid deposition in 22.5 percent of participants. After adjustment for age, sex, and APOEε4 allele carrier status, those with amyloid deposition had significantly worse sleep quality. Sleep quantity was not linked to amyloid deposition.
Maureen Handoko, Ph.D., from the University of Minnesota in Minneapolis, and colleagues investigated two specific Aβ oligomers in human cerebrospinal fluid in 48 older adults with mild cognitive impairment or Alzheimer's disease, 49 matched cognitively intact controls, and 10 younger normal controls. The researchers found that Aβ trimers and Aβ*56 levels increased with age. In the unimpaired group, Aβ trimers and Aβ*56 levels were raised in individuals with T-tau/Aβ1-42 ratios greater than a cut-off which differentiated unimpaired individuals from those with Alzheimer's disease. T-tau and p-tau181 were strongly related to Aβ trimers and Aβ*56 levels. These associations were attenuated in the impaired group.
"Prior to overt symptoms, one or both of the Aβ oligomers, but not fibrillar Aβ, is coupled to tau; however, this coupling is weakened or broken when Alzheimer's disease advances to symptomatic stages," Handoko and colleagues write.
Two authors from the Ju study disclosed financial ties the pharmaceutical industry.
Abstract - Ju
Abstract - Handoko
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