John is Professor Emeritus John Hodges, Brain and Mind centre, University of Sydney.

John qualified in Medicine from London University with honours (1975) and undertook periods of psychiatric and neurological training in Southampton, Oxford and San Diego and obtained his MD in 1988. From 1997 to 2007 he was MRC Professor of Behavioural Neurology with joint appointments in the Department of Clinical Neuroscience at Addenbrooke’s Hospital and the MRC Cognition and Brain Sciences Unit Cambridge. He moved to Sydney in 2007 obtaining an ARC Federation Fellowship and established FRONTIER with the support from the ARC and NHMRC. He has a longstanding interest in many aspects of cognition particularly in the context of neurodegenerative disorders. He is the author of over 450 journal articles and five books including Cognitive Assessment for Clinicians (OUP 2007), Early Onset Dementia (OUP) Frontotemporal Dementia Syndromes (CUP, 2007).

Abstract Although the syndrome of behavioural variant Frontotemporal Dementia (bvFTD) was recognised many years ago, the centrality of changes in social cognition became apparent around 20 years ago when it was realised that these features overlap considerably with those seen in people with Autistic Spectrum disorder (ASD). In 2002 we were the first show that patients with bvFTD had impaired performance of a range of theory of mind tasks thus consolidating the clinical overlap between bvFTD and ASD, although those with the former differ in that they progress to full blown dementia and eventual death.

After running a cognitive disorders clinic in Cambridge for a decade, we recognised a subgroup of men presenting with abnormal social cognition who had been initially diagnosed with bvFTD, yet failed to progress over many years of follow up. They have been termed ‘phenocopy cases’. It has been suggested that such men have lifelong ASD presenting in mid- to late-life because of changes in life circumstances (such as a new partner) or the additional effects of brain ageing. The aetiology of the phenocopy syndrome remains, however, contentious.

To complicate the picture, it was recognised that patients with the C9orf72 mutation (identified in 2011 and found to be the commonest genetic cause of FTD) may progress very slowly. A study screening for the mutation in phenocopy cases showed the mutation to be rarely present. In contrast, a study involving 1,400 family members of FTD patients (with and without the mutation) showed that children from C9orf72 families had a significantly higher rate of ASD. Clearly there is much to be leant. Does late life ASD simply mimic bvFTD, could ASD be a risk factor for FTD or are they separate disorders with a shared genetic background? As usual, more studies are needed.