Ellen Callahan, MD, PhD, is a behavioral neurologist and clinical researcher at an academic memory and aging center. She writes about cognitive disorders and dementia. Over 23 years in clinical neurology, she has evaluated patients with memory impairment and directed clinical trials tracking neurodegenerative conditions. Her laboratory research examines spinal fluid biomarkers to identify protein changes during the earliest stages of Alzheimer’s disease. Callahan received an undergraduate degree in cognitive science from Fordham University and completed a doctorate in neuroscience at Weill Cornell Medicine.