Born in Northern Ireland on 28 March 1955, John Thomas Alderdice was the eldest child of the late Rev David Alderdice and the late Mrs Helena Alderdice (nee Shields). He was educated at Donaghcloney Primary School, Strandtown Primary School in Belfast, and Ballymena Academy, where he was Deputy Head Boy.

In 1973 he went up to The Queen’s University of Belfast to read medicine and graduated MB, BCh, BAO in 1978. He qualified as a member of the Royal College of Psychiatrists (MRCPsych) in 1983, and this was followed by higher specialist training in Psychoanalytic Psychotherapy.

In January 1988 he was appointed by the Eastern Health and Social Services Board as Ireland’s first Consultant Psychotherapist going on later to establish and run, until his retirement from clinical practice in March 2010, the Centre for Psychotherapy in Belfast – an academic and clinical centre of excellence for the speciality within Ireland.

From 1991 to 1999 he was also an Honorary Lecturer (subsequently Senior Lecturer) in the Faculty of Medicine, at Queen’s University, Belfast where he established and taught a MMedSc degree course in Psychotherapy. In 1991 he was also appointed the first Director of the Northern Ireland Institute of Human Relations, a position he held until October 1994. He became widely known in Ireland for his lectures, broadcasts and publications on mental health. From 1993 to 1997 he was the first Executive Medical Director of South and East Belfast Health & Social Services Trust, at that time one of Northern Ireland’s largest health and social care providers. In 1997 he was elected a Fellow of the Royal College of Psychiatrists (FRCPsych). 

He had already for some years taken an active interest in the psychology of violent political conflict, travelling to various parts of the world to follow his involvement in this field. In 1999 he was appointed Honorary Professor in the Faculty of Medicine, at the University of San Marcos, Lima and in 2000 he was appointed an Honorary Member of the Peruvian Psychiatric Association. His contribution was also being recognized in the UK and in July 2001 he was elected an Honorary Fellow of the Royal College of Psychiatrists and an Honorary Affiliate of the British Psychoanalytical Society. He cooperated for some years with colleagues at the University of Virginia in Charlottesville and was from 2006 to 2010 a Visiting Professor in the Department of Psychiatry at UVa, as well as Co-chairman of the Critical Incident Analysis Group (CIAG) with Ed Meese (the former US Attorney-General).