Cerebral Cortex Advance Access published online on July 16, 2008
Cerebral Cortex, doi:10.1093/cercor/bhn113
The Cortical Signature of Alzheimer's Disease: Regionally Specific Cortical Thinning Relates to Symptom Severity in Very Mild to Mild AD Dementia and is Detectable in Asymptomatic Amyloid-Positive Individuals
1 Department of Neurology, 2 Massachusetts Alzheimer's Disease Research Center, 3 Athinoula A. Martinos Center for Biomedical Imaging, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA, 4 Division of Cognitive and Behavioral Neurology, Department of Neurology, Brigham & Women's Hospital, Boston, MA, USA, 5 Department of Psychiatry, 6 Department of Radiology, Massachusetts General Hospital and Harvard Medical School, Boston, MA, USA, 7 Department of Internal Medicine, Brigham & Women's Hospital, Boston, MA, USA, 8 Department of Neurology and Alzheimer's Disease Research Center, Washington University School of Medicine, St Louis, MO, USA, 9 Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology, Cambridge, MA, USA, 10 Department of Psychology and Howard Hughes Medical Institute, Harvard University, Cambridge, MA, USA
Address correspondence to Brad Dickerson, MD, MGH Gerontology Research Unit, 149 13th St, Suite 2691, Charlestown, MA 02129, USA. Email: bradd{at}nmr.mgh.harvard.edu.
Alzheimer's disease (AD) is associated with neurodegeneration in vulnerable limbic and heteromodal regions of the cerebral cortex, detectable in vivo using magnetic resonance imaging. It is not clear whether abnormalities of cortical anatomy in AD can be reliably measured across different subject samples, how closely they track symptoms, and whether they are detectable prior to symptoms. An exploratory map of cortical thinning in mild AD was used to define regions of interest that were applied in a hypothesis-driven fashion to other subject samples. Results demonstrate a reliably quantifiable in vivo signature of abnormal cortical anatomy in AD, which parallels known regional vulnerability to AD neuropathology. Thinning in vulnerable cortical regions relates to symptom severity even in the earliest stages of clinical symptoms. Furthermore, subtle thinning is present in asymptomatic older controls with brain amyloid binding as detected with amyloid imaging. The reliability and clinical validity of AD-related cortical thinning suggests potential utility as an imaging biomarker. This "disease signature" approach to cortical morphometry, in which disease effects are mapped across the cortical mantle and then used to define ROIs for hypothesis-driven analyses, may provide a powerful methodological framework for studies of neuropsychiatric diseases.
Key Words: Alzheimer's disease • cerebral cortex • magnetic resonance imaging • medial temporal lobe • parietal cortex