As a medical undergraduate of TCD, Prof O’Neill spent a year in Marseilles as a volunteer with an NGO working with older people, and with electives in Hamburg. He subsequently trained as a geriatrician in St James’s Hospital and the University of Bristol.

Following an appointment as a consultant geriatrician in Selly Oak Hospital, Birmingham he returned to Dublin and currently is the senior academic in Medical Gerontology at the TCD campus at Tallaght University Hospital.

He has pioneered a number of initiatives, including first Medical Director of the Alzheimer Society of Ireland; founder-Chair of Council on Stroke of Irish Heart Foundation; co-PI on first Irish longitudinal study on ageing (HESSOP-2); co-PI on Irish National Audits of Stroke and Dementia Care; founder-editor of first Irish gerontology journal ‘Irish Ageing Studies Review’; chair of Irish government Working Group on Elder Abuse, producing blueprint ‘Protecting Our Future’; co-founder National Centre for Arts and Health; member of the team that developed the European Masters in Gerontology; co-PI on first Irish Cochrane Review on ageing; and founder member and subsequent president of the European Union Geriatric Medicine Society.

He has subsequently led the Irish Traffic Medicine Programme, which has developed innovative Certificates in Traffic Medicine and Road Safety with the Royal College of Physicians in Ireland. He served on the founding steering committee of Age-Friendly University, Dublin City University and is a member of the Expert Advisory Board of DCU’s Age-Friendly University Initiative. He has been extensively involved in its promotion, successfully proposing adoption in TCD and the Royal College of Physicians of Ireland. He has been honoured as the first Irish gerontologist to be awarded Fellowship of the Gerontological Society of America, and the first Irish geriatrician to be awarded Fellowship of the American Geriatrics Society.