Disrupted Sleep Increases Risk of Alzheimer Disease

Christian Benedict, PhD

A rough night of sleep could have ripple effects that lead to an increased risk of Alzheimer disease.

Investigators, led by Christian Benedict, PhD, Departments of Neuroscience and Medical Sciences, Uppsala University, examined whether disrupted sleep increases cerebrospinal fluid levels of tau and β-amyloid (Aβ) and is associated with an increased risk of Alzheimer disease.

The aim to determine whether acute sleep loss alters diurnal profiles of plasma-based Alzheimer disease-associated biomarkers.

The 2-condition crossover study included 15 healthy young men participants in 2 standardized sedentary in-laboratory conditions in randomized order—normal sleep compared to overnight sleep loss.

Plasma levels of total tau (t-tau), Aβ40, Aβ42, neurofilament light chain (NfL), and glial fibrillary acidic protein (GFAP) were assessed using ultrasensitive single molecule array assays or ELISAs, in the fasted state in the evening prior to, and in the morning after, each intervention.

In response to sleep loss (+17.2%), compared with normal sleep (+1.8%), the evening to morning ratio was increased for total tau (P =.035). There no changes between the sleep conditions were found for levels of Aβ40, Aβ42, NfL, or GFAP (all P >.10).

The Alzheimer disease risk genotype rs4420638 did not significantly interact with sleep loss—related diurnal changes in plasma levels of Aβ40 or Aβ42 (P >.10), while plasma levels of Aβ42 (−17.1%) and GFAP (−12.1%) exhibited an evening to morning decrease across conditions (P <.05).

“Our exploratory study suggests that acute sleep loss results in increased blood levels of t-tau,” the authors wrote. “These changes provide further evidence that sleep loss may have detrimental effects on brain health even in younger individuals.”

The investigators believe larger cohorts are warranted to delineate sleep compared with circadian mechanisms, implications for long-term recurrent conditions, as well as interactions with other lifestyle and genetic factors.

Sleep duration could also help forecast psychiatric disorders for school-aged children, according to a new study.

A team led by Bror M. Ranum, Department of Psychology, Norwegian University of Science and Technology (NTNU), examined the long-term and bidirectional link between the duration of sleep and symptoms of psychiatric disorders for school-aged children ages 6, 8, 10, and 12.

The population-based cohort study included 799 children that participated in the Trondheim Early Secure Study, where all time-invariant confounders and baseline levels of study variables were accounted for. The investigators conducted a representative, stratified random sample of children in the study born between January 1, 2003 and December 31, 2004.

The participants were followed up biennially from 4-12 years old and the data was analyzed in 2019.

Sleep duration was assessed with 1 week of continuous use of triaxial accelerometer.

Symptoms of emotional disorders such as anxiety and depression and behavioral disorders, including oppositional defiant, conduct, and ADHD, were measured by semistructured clinical interviews using the Preschool Age Psychiatric Assessment and the Child and Adolescent Psychiatric Assessment with parents and children from age 8.

In the study, short sleep duration was prospectively tied to symptoms of psychiatric disorders only at younger ages, but not older ages. There was no evidence found for the opposite direction of association.

The study, “Effects of acute sleep loss on diurnal plasma dynamics of CNS health biomarkers in young men,” was published online in Neurology.