Following graduation in 1941, Carstairs worked in general medicine. He was an assistant physician at the Royal Edinburgh Hospital for a year. He served as a medical officer with the Royal Air Force between 1942 and 1946. In 1953, he began his career in psychiatry when he was appointed a senior registrar at the Maudsley Hospital, a psychiatric hospital in London, England. There he worked with chronic psychiatric patients under the supervision of Sir Aubrey Lewis. During his work, he come to the conclusion that patients with schizophrenia needed a neutral environment to cope with their condition and returning them to an 'emotionally charged family setting' would only set back their recovery. He also discovered that improved motivation in patients helped their rehabilitation. Carstairs received his medical degree from the University of Edinburgh in 1959. In 1960, he was appointed head of a new Medical Research Council unit based at University College London. This unit led the study of psychiatric epidemiology in the United Kingdom. When he moved to Edinburgh in 1961, he moved the unit with him and continued its research. He stood down as director in 1971, and was followed by Norman Kreitman. From 1968 to 1972, he was President of the World Mental Health Organization. While holding that post, he was involved in the development of psychiatric facilities in under-developed countries. In 1978, he left academia and devoted his time to advising the World Health Organization on developing psychiatric services in India, with emphasis on making them appropriate to Asian needs.
Academic career
In 1961, Carstairs was appointed Professor of Psychological Medicine at the University of Edinburgh. At the university he created a new working group of academics and practising psychiatrists for research and teaching; it was the first such group created outside London. At the university he taught a wide range of course at both undergraduate and graduate level. He gave the 1962 Reith Lectures, a renowned public lecture series broadcast on BBC Radio, titled This Island Now. In one lecture he condoned pre-marital sex, which produced controversy. His statement of belief was offensive to many British Christians, particularly given that he was the son of a clergyman. In January 1973, he was appointed Vice-Chancellor of the University of York. He was only the second person to head the university as it had only been established in 1963. The 1970s were a difficult time to be involved in university leadership in the United Kingdom. The country was in recession and student protests were frequent. He had plans to expand the university both physically and in the number of subjects it taught, but because of the hostile atmosphere he faced these were not achieved during his vice-chancellorship. This experience meant that he never returned to full-time academia after leaving the post in the summer of 1978.
Later life
Carstairs suffered from senile dementia in his later years. He withdrew from professional life, and was cared for by his first wife. He died at his Edinburgh home on 17 April 1991.