title: Sleep evoked delta frequency responses show a linear decline in amplitude across the adult lifespan.
abstract: Aging is associated with many changes in sleep, with one of the most prominent being a reduction in slow wave sleep. Traditional measures of this phenomenon rely on spontaneous activity and typically confound the incidence and amplitude of delta waves. The measurement of evoked K-complexes during sleep, enable separate assessment of incidence and amplitude taken from the averaged K-complex waveform. The present study describes data from 70 normal healthy men and women aged between 19 and 78 years. K-Complexes were evoked using short auditory tones and recorded from a midline array of scalp sites. Significant reductions with age were seen in the amplitude of the N550 component of the averaged waveform, which represents the amplitude of the K-complex, with linear regression analysis indicating approximately 50% of the variance was due to age. Smaller, yet still significant reductions were seen in the ability to elicit K-complexes. The data highlight the utility of evoked K-complexes as a sensitive marker of brain aging in men and women.
authors.affiliation: Center for Health Sciences, SRI International, Menlo Park, CA 94025, USA. ian.colrain@sri.com
authors.forename: Ian M
authors.initials: IM
authors.lastname: Colrain
authors.forename: Kate E
authors.initials: KE
authors.lastname: Crowley
authors.forename: Christian L
authors.initials: CL
authors.lastname: Nicholas
authors.forename: Lamia
authors.initials: L
authors.lastname: Afifi
authors.forename: Fiona C
authors.initials: FC
authors.lastname: Baker
authors.forename: Mayra
authors.initials: M
authors.lastname: Padilla
authors.forename: Sharon R
authors.initials: SR
authors.lastname: Turlington
authors.forename: John
authors.initials: J
authors.lastname: Trinder
mesh_terms: D000161:Acoustic Stimulation; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D002540:Cerebral Cortex / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012890:Sleep / Q000502:physiology*