Niall completed his primary BA degree in Psychology at UCD in 1991 followed by an MSc in Neuropsychology at the University of Wales in 1992. He undertook his clinical psychology training (MSc, 1993-1996) at the Institute of Psychiatry, King's College London where he also subsequently completed his PhD in Neuropsychology in 2005. He completed his post-qualification Diploma in Clinical Neuropsychology at the Institute of Psychiatry in 1997 while working as a neuropsychologist at the Lishman Brain Injury Unit, Maudsley Hospital,London.