Dr. Johnson is a Professor of Radiology and Neurology at the Harvard Medical School. He is also an Associate Radiologist and the Director of Molecular Neuroimaging in the Division of Nuclear Medicine and Molecular Imaging (Department of Radiology ) at the Massachusetts General Hospital (MGH). Dr. Johnson also serves as an associate physician and staff neurologist in the Memory Disorders Unit at the Brigham and Women’s Hospital as well as a Clinical Associate in Neurology at the MGH.
Dr. Johnson is co-director of the Neuroimaging Program of the Massachusetts Alzheimer's Disease Research Center and its Dominantly Inherited Alzheimer Network (DIAN ) research initiatives. He oversees the Clinical Brain Positron Emission Tomography (PET) Service at the MGH and also practices as a neurologist that specializes in neurodegenerative disorders.
Dr. Johnson maintains an Internet teaching atlas of neuroimaging known as the Whole Brain Atlas: www.med.harvard.edu/AANLIB/home.html 
Dr. Johnson's major research interests include the early diagnosis and treatment monitoring of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, and dementia with Lewy bodies.
Johnson KA, Gregas M, Becker JA, Kinnecom C, Salat DH, Moran EK, Smith EE, Rosand J, Rentz DM, Klunk WE, Mathis CA, Price JC, Dekosky ST, Fischman AJ, Greenberg SM. Imaging of Amyloid Burden and Distribution in Cerebral Amyloid Angiopathy. Ann Neurology 2007; 62: 229-234.
Gomperts S, Rentz DM, Moran EK, Becker JA, Locascio JJ, Klunk WE, Mathis C, Elmaleh DR, Shoup T, Fischman AJ, Hyman BT, Growdon JH, Johnson KA. Imaging Amyloid Deposition in Lewy Body Diseases. Neurology 2008; 71: 903-910. [PMCID: 2637553].
Greenberg S, Grabowski TJ, Gurol ME, Skehan ME, Nandigam RNK, Becker JA, Garcia-Alloza M, Prada C, Frosch MP, Rosand J, Smith EE, Johnson KA. Detection of Isolated Cerebrovascular ß-Amyloid with Pittsburgh Compound B. Ann Neurology 2008; 64: 587-591. [PMCID: 2605158].
Buckner R, Sepulcre J, Talukdar T, Krienen F, Liu H, Trey Hedden T, Andrews-Hanna J, Sperling RA, Johnson KA. Cortical Hubs Revealed by Intrinsic Functional Connectivity: Mapping, Assessment of Stability, and Relation to Alzheimer's Disease. J Neurosci 2009; 29:1860-1873. [PMCID: 2750039].
Hedden T, Van Dijk K, Becker JA, Mehta A, Sperling RA, Johnson KA, Buckner RL. Disruption of Functional Connectivity in Clinically Normal Older Adults Harboring Amyloid Burden. J Neuroscience 2009; 29: 12686-12694. [PMCID: 2808119].
Sperling R, LaViolette P, O'Keefe K, O’Brien J, Rentz D, Pihlajamaki M, Marshall G, Hyman B, Selkoe D, Hedden T, Buckner R, Becker J, Johnson K. Amyloid Deposition is Associated with Impaired Default Network Function in Older Persons without Dementia. Neuron 2009; doi: 10.1016. [PMCID: 2738994].
More publications may be accessed at www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed