title: Olfactory cortex degeneration in Alzheimer's disease and mild cognitive impairment.
abstract: BACKGROUND
  Olfactory deficits are prevalent in patients with Alzheimer's disease (AD) and mild cognitive impairment (MCI). These symptoms precede clinical onset of cognitive and memory deficits and coincide with AD pathology preferentially in the central olfactory structures, suggesting a potential biomarker for AD early detection and progression.
  
  
  OBJECTIVE
  Therefore, we tested the hypothesis that structural degeneration of the primary olfactory cortex (POC) could be detected in AD as well as in MCI patients and would be correlated with olfactory functional magnetic resonance imaging (fMRI) alterations, reflecting loss of olfactory cortex activity.
  
  
  METHODS
  Total structural volumes and fMRI activation volumes of the POC and hippocampus were measured along with olfactory and cognitive behavioral tests in 27 cognitively normal (CN), 21 MCI, and 15 AD subjects.
  
  
  RESULTS
  Prominent atrophy in the POC and hippocampus was found in both AD and MCI subjects and correlated with behavioral measurements. While behavioral and volumetric measurements showed a gradual decline from CN to MCI to AD, olfactory activation volume in the POC and hippocampus showed a steeper decline in the MCI group compared to corresponding tissue volume, resembling the AD group.
  
  
  CONCLUSIONS
  Decline in olfactory activity was correlated with the AD structural degeneration in the POC. A more prominent olfactory activity deficit than that of behavioral and tissue volume measurements was shown in the MCI stage. Olfactory fMRI may thus provide an earlier and more sensitive measure of functional neurodegeneration in AD and MCI patients.
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Megha M
authors: MM
authors: Vasavada
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Jianli
authors: J
authors: Wang
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA Department of Neurology, Pennsylvania State University College of Medicine, Hershey, PA, USA Department of Neural & Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Paul J
authors: PJ
authors: Eslinger
authors: Unity Rehabilitation and Neurology at Ridgeway, Rochester, NY, USA.
authors: David J
authors: DJ
authors: Gill
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Xiaoyu
authors: X
authors: Sun
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Prasanna
authors: P
authors: Karunanayaka
authors: Department of Radiology, Pennsylvania State University College of Medicine, Hershey, PA, USA Department of Neurosurgery, Pennsylvania State University College of Medicine, Hershey, PA, USA.
authors: Qing X
authors: QX
authors: Yang
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000150:complications*; D000704:Analysis of Variance; D060825:Cognitive Dysfunction / Q000150:complications*; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008609:Mental Status Schedule; D008875:Middle Aged; D019636:Neurodegenerative Diseases / Q000209:etiology*; D000857:Olfaction Disorders / Q000209:etiology* / Q000473:pathology; D066194:Olfactory Cortex / Q000098:blood supply / Q000473:pathology*; D010100:Oxygen / Q000097:blood
chemical_list: D010100:Oxygen
keywords: Alzheimer's disease; MRI; functional MRI; mild cognitive impairment; olfaction