Mady Hornig (born 1957) is an American psychiatrist and an associate professor of epidemiology at Columbia University's Mailman School of Public Health. A physician-scientist, her research involves clinical, epidemiological, and animal model research on autism and related neurodevelopmental conditions. She directs the clinical core of an international investigation of the role of Borna disease virus in human mental illness and participates as a key investigator for the Autism Birth Cohort (ABC) project, a large prospective epidemiological study, based in Norway, that is identifying how genes and timing interact with environmental agents preceding the onset of autism spectrum diagnoses. In 2006, she was appointed as Guest Professor at the School of Basic Medical Science of Beijing University in Beijing, China. Hornig has been described as an "anti-mercury activist". Along with CII director W. Ian Lipkin and colleague Thomas Briese, she is currently investigating measles virus RNA sequences in bowel biopsies of children with autism spectrum disorders. Formulating a "three strikes" model of causation that integrates genetics, the environment and developmental neurobiology, Hornig posits that some cases of autism may represent the unfortunate coincidence of genetic vulnerability (first dimension) and exposure to environmental factors (second dimension) at a critical period of brain development (third dimension). She is examining how brain damage from infections, immune system dysfunction, neurotoxins, and other chemical or psychosocial stress factors, or host responses to these environmental agents, can lead to neurodevelopmental and other central nervous system disorders, thereby contributing to autism, schizophrenia, attention deficit hyperactivity disorder, obsessive compulsive disorders, and mood disorders. Education Hornig received a bachelor's degree in 1978 from Cornell University, where she was a College Scholar; an MA in psychology in 1983 from the New School for Social Research, and an MD in 1988 from the Medical College of Pennsylvania, in Philadelphia. Between 1988 and 1992, Hornig served her residency in psychiatry at the University of Vermont. Under a National Research Service Award from the National Institutes of Mental Health, she completed a postdoctoral fellowship in neuropsychopharmacology on the Depression Research Unit of the University of Pennsylvania from 1992 to 1994. Career In the 1990s, Hornig investigated the potential link between the Borna virus and depression in humans. Hornig has been described as being part of an "inner circle of anti-mercury activists" whose work has been funded in part by the anti-mercury campaigning group SafeMinds. In 2008, she published a study concluding that there was