title: Delta Activity at Sleep Onset and Cognitive Performance in Community-Dwelling Older Adults.
abstract: OBJECTIVE
  Frontal intermittent rhythmic delta activity (FIRDA) has long been considered to be an abnormal variant in the electroencephalogram (EEG) among older adults. Prior work also indicates a predominance of slow wave EEG activity among patients with dementia. However, instability of state control occurring with aging generally and among many neurodegenerative diseases raises the possibility that FIRDA might represent the intrusion of sleep related elements of the EEG into the waking state. We examined delta activity at sleep onset (DASO) in community-dwelling, older adults without dementia, and examined whether this activity is related to poorer cognitive performance.
  
  
  METHODS
  153 community-dwelling, older adults without dementia underwent overnight polysomnography and measures of global cognition, delayed verbal memory, information processing speed, attention, inhibition, verbal naming, and visuospatial ability. Delta activity during sleep/wake transitions (scored either as Waking or N1) was analyzed visually.
  
  
  RESULTS
  Participants were 83 women and 70 men, mean age 71.3 ± 0.6 y. DASO was present in 30 participants (19.6%). Age, years of education, sex, and body mass index did not differ between DASO (+) and (-) groups. Multiple regression analyses indicated faster reading of the Stroop color words in DASO (+) subjects (P = 0.007). None of the other cognitive domains differed between the two groups.
  
  
  CONCLUSIONS
  DASO was relatively common in our sample of community-dwelling, older adults without dementia. DASO was not associated with poorer performance on any cognitive domain. Instead, individuals with DASO demonstrated better performance on a simple reading task. Although these findings suggest that an abnormal EEG activity may represent normal variation, our work underscores the importance of distinguishing DASO from FIRDA when examining sleep in older adults.
  
  
  CONCLUSIONS
  A commentary on this article appears in this issue on page 725.
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|Sierra Pacific Mental Illness Research Education and Clinical Centers (MIRECC), VA Palo Alto Health Care System, Palo Alto, CA.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kawai
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|Sierra Pacific Mental Illness Research Education and Clinical Centers (MIRECC), VA Palo Alto Health Care System, Palo Alto, CA.|School of Psychology, University of Queensland, Brisbane, Australia.
authors.forename: Sherry A
authors.initials: SA
authors.lastname: Beaudreau
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|Geriatric Research Education and Clinical Center, VA Palo Alto Health Care System, Palo Alto, CA.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Gould
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|Sierra Pacific Mental Illness Research Education and Clinical Centers (MIRECC), VA Palo Alto Health Care System, Palo Alto, CA.
authors.forename: Nathan C
authors.initials: NC
authors.lastname: Hantke
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|California School of Professional Psychology at Alliant International University, Alhambra, CA.
authors.forename: Josh T
authors.initials: JT
authors.lastname: Jordan
authors.affiliation: Department of Psychiatry and Behavioral Sciences, Stanford University, School of Medicine, Stanford, CA.|Sierra Pacific Mental Illness Research Education and Clinical Centers (MIRECC), VA Palo Alto Health Care System, Palo Alto, CA.|School of Psychology, University of Queensland, Brisbane, Australia.
authors.forename: Ruth
authors.initials: R
authors.lastname: O'Hara
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology* / Q000523:psychology*; D001288:Attention / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D003072:Cognition Disorders / Q000175:diagnosis; D003700:Delta Rhythm; D005260:Female; D006801:Humans; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D017286:Polysomnography; D011932:Reading; D012890:Sleep / Q000502:physiology*; D057190:Stroop Test
keywords: DASO; FIRDA; cognition; delta activity at sleep onset; sleep