In 1961, he began his career as a research psychologist at the Walter Reed Army Institute of Research where, in 1970, he was appointed Deputy Director of Neuropsychiatry.
He is the Scientia Professor of Neuropsychiatry at the University of New South Wales (UNSW), Australia, the director of the Centre for Healthy Brain Ageing (CHeBA), UNSW, and the Clinical Director of the Neuropsychiatric Institute (NPI) at the Prince of Wales Hospital, Sydney, Australia 1.
He was a neurophysiologist in the Division of Neuropsychiatry at the Walter Reed Army Institute of Research (1951–1964) and a neuroanatomist at McLean Hospital (1975).