Affiliations: [a] Section of Geriatric Psychiatry, University of Heidelberg, Heidelberg, Germany | [b] German Cancer Research Center, Heidelberg, Germany
Correspondence:
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Corresponding author: Dr. med. Philipp A. Thomann, Section of Geriatric Psychiatry, University of Heidelberg, Voßstr. 4, 69115 Heidelberg, Germany. Tel.: +49 6221 56 38091; Fax: +49 6221 56 1742; E-mail: philipp_thomann@med.uni-heidelberg.de.
Abstract: There is increasing histopathological evidence that the olfactory bulb and tract (OBT) is a primary focus of neurodegenerative changes in Alzheimer's disease (AD). Correspondingly, high-resolution magnetic resonance imaging revealed significant atrophy of the OBT in manifest AD. Whether these alterations are already present in mild cognitive impairment, the assumed preclinical stage of AD, has not been investigated yet. OBT volumes were assessed by manual tracing in 29 patients with mild cognitive impairment, 27 patients with probable AD, and 30 healthy controls. In a second step, voxel based morphometry was used to investigate the potential association between OBT atrophy and morphological changes in other brain regions. Patients had significantly lower OBT volumes when compared to controls, with atrophy being most prominent in the AD group. In addition, OBT atrophy was associated with a decreased medial temporal lobe (MTL) gray matter density bilaterally. Our findings indicate that neurodegeneration in OBT and MTL regions is linked and suggest that OBT volume might be a surrogate marker in AD.
Keywords: Alzheimer's disease, magnetic resonance imaging, mild cognitive impairment, olfactory bulb and tract, voxel based morphometry
