Alwyn Lishman liked to tell people that he wrote his classic textbook Organic Psychiatry (1978) only because the £500 advance would enable him to buy the Bechstein grand piano that he coveted. Yet he put his heart and soul into it, setting the subject of neuropsychiatry on a new footing, and trained generations of successors to approach mental illness with insights from both brain and mind.

Trained in neurology and psychiatry, Lishman, who has died aged 89, was not the first to bridge the two subjects. There was a strong tradition among German neurologists of the late-19th century to look for underlying physical causes for conditions such as dementia and schizophrenia. But when he qualified in medicine in postwar Britain, Lishman found that neurology had little to say about the mind, while psychiatry was strongly influenced by psychoanalysis. He made it his mission to build a new discipline that combined the two. While using newly available techniques to explore abnormalities in the brain, he rooted his practice in psychiatry, listening to his patients and taking their circumstances into account.

“There was no reason in neuropsychiatry to forget about interpersonal relationships when treating someone with dementia, … [or] the impact of culture when dealing with alcoholism,” he told the Australian psychiatrist Michael Salzberg in an interview in 2002. “Everything we had learned [in psychiatry] applied to people with neuropsychiatric conditions.”

As part of his training in the early 1960s Lishman had completed a thesis on psychiatric symptoms in 670 soldiers with penetrating wounds to the head, who had been followed over five years by his former mentor Ritchie Russell at Oxford University. Lishman’s research career took off again in the late 70s when the Institute of Psychiatry in London, where he became professor of neuropsychiatry in 1979, took delivery of one of the first research CT scanners.

For the first time he could examine changes in the brains of living patients. He encouraged his PhD student Maria Ron (now emeritus professor of neuropsychiatry at UCL Institute of Neurology) to study the brains of chronic alcoholics, showing that if they gave up drinking their atrophied brains recovered, though only partially. He later used more advanced scanning techniques such as MRI to study other conditions such as the psychosis that affects some patients with epilepsy.

The first edition of Organic Psychiatry, subtitled The Psychological Consequences of Cerebral Disorder, took seven years to write while he continued full-time work as a clinical psychiatrist, helped his wife to bring up two small children and cared for elderly relatives. Among many other administrative roles, in 1987 he was founding president of the British Neuropsychiatry Association, which awards an annual prize for early career researchers in his name.

Lishman was born in Houghton-le-Spring, Co Durham (now Tyne and Wear), the younger child (he had an older sister, Valerie) of Madge (nee Young), a teacher, and George Lishman. The family was influential in the town thanks to the successful tallow chandlery founded by Alwyn’s great-grandfather, a former mineworker, that supplied candles for mining and shipbuilding all over the north-east. Alwyn’s father had started training as a dentist and hoped to move on to medicine, but after being taken prisoner during the first world war he was unable to complete his studies and managed the family business.

Alwyn attended Houghton-le-Spring grammar school and, having played the piano since the age of five, intended to be a musician. But he succumbed to “relentless pressure” from his parents to become a doctor and in 1950 went to Birmingham University to study physiology and anatomy. There he was lucky enough to work in the laboratory of Solly Zuckerman, later government chief scientist, who inspired him to continue with research and complete his medical qualification.

During his national service in the late 50s, he worked at a military hospital near Oxford, researching head injury, epilepsy and other topics under a succession of distinguished neurologists. Russell, a head injury specialist, took him on as registrar after his military service ended. A career in neurology beckoned, but Lishman had doubts. There seemed little he could do for his patients once he had diagnosed their condition. He had begun to read up on psychology and psychiatry, and decided he was more interested in the mind. He later said it “took a certain amount of unworldliness to make the move”, but he went to the Maudsley hospital in Denmark Hill, London, for psychiatric training.

After qualifying in 1966 he spent a year as a consultant in psychological medicine at the National Hospital for Nervous Diseases in Queen Square, London, examining neurological patients who had psychological symptoms. In 1967 he returned to the Maudsley as a consultant, and remained there until his retirement. He was a kind and generous mentor to his junior colleagues, many of whom went on to hold chairs in neuropsychiatry. Maria Ron recalls that as well as offering her the chronic alcoholism problem for her thesis, “he spent a lot of time discussing things with me, teaching me how to write properly. I was Lishmanised!”

He continued to be an accomplished keyboard player. In addition to his Bechstein, he built himself a harpsichord and regularly played his local church organ. His idea of a holiday was to tour Europe visiting the organs in baroque churches.

In 1966 he married Marjorie Loud, a psychiatric social worker, and they had two children, Victoria and William. Marjorie later developed a slow-growing brain tumour and Lishman took early retirement in 1993 in order to care for her, though he continued to work on the third (1997) edition of his textbook.

Marjorie died in 2000. Lishman is survived by his children and two grandchildren.

• William Alwyn Lishman, neuropsychiatrist, born 16 May 1931; died 24 January 2021

• This article was amended on 5 March 2021. Houghton-le-Spring was historically in Co Durham rather than Northumberland.