title: Intraindividual variability in HIV infection: evidence for greater neurocognitive dispersion in older HIV seropositive adults.
abstract: OBJECTIVE
  Both the prevalence and incidence of HIV infection among older adults are on the rise. Older adults are at increased risk of HIV-associated neurocognitive disorders, which have historically been characterized as an inconsistent or "spotty" pattern of deficits. Dispersion is a form of intraindividual variability (IIV) that is defined as within-person variability in performance across domains and has been associated with poorer neurocognitive functioning and incipient decline among healthy older adults. To our knowledge, no studies have yet examined dispersion in an aging HIV-infected sample.
  
  
  METHODS
  For the current study we examined the hypothesis that age and HIV infection have synergistic effects on dispersion across a battery of clinical and experimental cognitive tasks. Our well-characterized sample comprised 126 HIV-seropositive individuals (HIV+) and 40 HIV-seronegative comparison individuals (HIV-), all of whom were administered a comprehensive neuropsychological battery.
  
  
  RESULTS
  Consistent with our hypothesis, an age by HIV serostatus interaction was observed, with the older HIV+ group demonstrating a higher level of dispersion relative to older HIV- and younger HIV+ individuals, even when potentially confounding demographic and medical factors were controlled.
  
  
  CONCLUSIONS
  Our results demonstrate that older HIV+ adults produce greater dispersion, or intraindividual variability in performance across a range of tests, which may be reflective of cognitive dyscontrol to which this population is vulnerable, perhaps driven by the combined effects of aging and HIV infection on prefrontostriatal systems.
authors.affiliation: Department of Psychiatry, University of California, San Diego, CA 92103, USA. eemorgan@ucsd.edu
authors.forename: Erin E
authors.initials: EE
authors.lastname: Morgan
authors.forename: Steven Paul
authors.initials: SP
authors.lastname: Woods
authors.forename: Lisa
authors.initials: L
authors.lastname: Delano-Wood
authors.forename: Mark W
authors.initials: MW
authors.lastname: Bondi
authors.forename: Igor
authors.initials: I
authors.lastname: Grant
mesh_terms: D000328:Adult; D000375:Aging / Q000523:psychology*; D016022:Case-Control Studies; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000150:complications / Q000175:diagnosis*; D005260:Female; D006679:HIV Seropositivity / Q000150:complications* / Q000523:psychology; D006801:Humans; D007206:Individuality; D008297:Male; D008606:Mental Processes; D009483:Neuropsychological Tests; D012016:Reference Values