After completing an intercalated BSc in Psychology and Basic Medical Sciences, Professor MacCabe qualified in medicine at the University of London in 1995. He subsequently undertook his basic and higher specialist training in Psychiatry at the Maudsley Hospital from 1997 to 2004. In 2004, he secured a joint MRC/Department of Health Special Training Fellowship in Health of the population research, collaborating with the Department of Medical Epidemiology and Biostatistics at the Karolinska Institute in Stockholm. Professor MacCabe earned an MSc in Epidemiology from the London School of Hygiene and Tropical Medicine in 2006 and completed his PhD in 2008. In 2009, he received a Clinical Senior Lectureship from the Higher Education Funding Council for England and was later granted a personal chair as Professor of Epidemiology and Therapeutics at King's College London in 2019.
Since 2005, Professor MacCabe has served as an honorary consultant psychiatrist at the National Psychosis Unit, where he is responsible for treating inpatients with severe psychosis and conducting clinical trials. Additionally, he sits on the Board of Trustees for the mental health charity SANE.
Professor MacCabe's research focuses on treatment-refractory schizophrenia and personalized medicine, aligning with his clinical responsibilities. His work addresses individuals whose psychosis has not responded to standard antipsychotic treatment. His research encompasses epidemiology, genetics, and neurochemistry underlying treatment-refractory schizophrenia, with a particular emphasis on identifying biomarkers for use in personalized medicine. Much of his research is conducted in collaboration with both UK and international partners.