According to his wife Ophelia, McPhail discovered in the 1990s that the left hemisphere of his brain was damaged. Then aged in his 70s, he had displayed signs of dementia since his 30s, and was eventually diagnosed with Alzheimer's disease. McPhail, with the support of medical specialists, associated the neurological symptoms with heading the leather football used in the 1950s, explaining how "the ball used to get very heavy when it rained – when you took that full in the forehead it nearly knocked you over."