Donald is a retired consultant in psychiatry of old age and former Chief Executive of the Mental Welfare Commission for Scotland. He trained in Glasgow and the East Midlands, became a consultant in 1989 at Leverndale Hospital, Glasgow and also held management positions from 1995 until he took up the post of head of the Mental Welfare Commission in 2003. Donald retired in 2014 but has kept himself busy teaching, being a non-executive director of NHS Greater Glasgow and Clyde, being a medical member of the Mental Health Tribunal for Scotland and being a trustee for (now) two charities.

Donald has had a long interest in palliative care. In the late 1980s, he provided specialist psychiatric input to a hospice in Derby. As a consultant psychiatrist, he directly provided palliative care for people with dementia, as well as giving advice on mental health aspects of the care of older people with life-limiting conditions in various settings. In his role at the Commission, Donald took a lead role in three important investigations into the care of people with mental illness towards the end of life. He also took a lead role in publishing ethical guidance on, among other subjects, consent to treatment, treatment for physical illness where the individual lacks capacity and refuses treatment, and giving medication in disguised form. These guidance documents are highly regarded within Scotland and elsewhere.

Donald is married with three adult sons. Although he lives in Newton Mearns on the outskirts of Glasgow, he is a regular Ayrshire visitor. When he remembers that he is supposed to be retired, he plays golf, supports Greenock Morton and takes his dog for days out on Ayrshire beaches.