Elevation of serum TNF-α levels in mild and moderate Alzheimer patients with daytime sleepiness

Abstract

Objectives: Sleep disturbance has been noted to accompany Alzheimer disease and is more pronounced as dementia severity increases. The aim of this study was to examine whether sleep disturbance in a cohort of patients with mild/moderate AD was associated with serum levels of IL-1β and TNF-α.

Methods: Forty three drug-free AD patients and twenty two healthy controls were evaluated. All subjects underwent two consecutive full-night polysomnography. Their daytime sleepiness was assessed by Epworth Sleepiness Scale (ESS). Serum levels of IL-1β and TNF-α were measured by enzyme linked immunoassays.

Results: AD patients showed lower sleep efficiency, more awakenings and less slow wave sleep (SWS). IL-1β was detectable only in two AD patients. Serum TNF-α concentrations did not differ significantly between AD patients and controls. When AD patients were classified as AD patients with daytime sleepiness (n=20, ESS>10) or AD patients without daytime sleepiness (n=23, ESS<10) according to their ESS scores, serum levels of TNF-α was significantly higher in AD patients with daytime sleepiness than that in those without daytime sleepiness or controls (32.7±17.9 vs 5.2±2.4, p<0.05; 40.9±22.3 vs 5.7±2.2, p<0.05). Serum level of TNF-α was significantly correlated with ESS score.

Discussion: These data indicate that daytime sleepiness in mild and moderate AD patients is associated with elevation of serum TNF-α concentrations.