title: Individuals with Down's syndrome demonstrate abnormal olfactory event-related potentials.
abstract: OBJECTIVE
  Recent research has demonstrated that individuals with Down's syndrome (DS) develop plaques and tangles in the brain similar to people with Alzheimer's disease. As a result, they show increased dementia and decreased olfactory functioning compared to healthy individuals. The olfactory event-related potential (OERP) has been used as an objective quantitative measure of olfactory functioning in normal and clinical populations. The present study investigated the utility of the latency and amplitude of the OERP components in examining olfactory dysfunction in DS individuals.
  
  
  METHODS
  OERPs were recorded monopolarly at the Fz, Cz and Pz electrode sites, using amyl acetate at a 60 s inter-stimulus interval, from individuals with DS (mean age 26.0 years) and age-matched normal controls. Participants were screened for nasal health and odor thresholds were assessed. Dementia was assessed using the dementia rating scale (DRS).
  
  
  RESULTS
  Results indicate that DS subjects have significantly longer latencies in the sensory (N1, P2, and N2) and cognitive (P3) components of the OERP than normal controls. Odor threshold was significantly associated with sensory OERP components. In addition, DS subjects with a higher level of dementia showed significantly longer P3 latencies than those with lower dementia levels.
  
  
  CONCLUSIONS
  The study suggests that the OERP may be a useful measure of olfactory dysfunction in DS which may precede developing dementia in this population.
authors.affiliation: Department of Psychology, San Diego State University, CA 92120-4913, USA.
authors.forename: S
authors.initials: S
authors.lastname: Wetter
authors.forename: C
authors.initials: C
authors.lastname: Murphy
mesh_terms: D000328:Adult; D004314:Down Syndrome / Q000503:physiopathology*; D004569:Electroencephalography; D005071:Evoked Potentials / Q000502:physiology*; D006801:Humans; D009830:Olfactory Bulb / Q000503:physiopathology*; D011930:Reaction Time / Q000502:physiology; D012903:Smell / Q000502:physiology