Footnotes

• Contributors ED contributed to the conception and design of the study, interpretation of the data, and drafting and revising of the manuscript. SLF contributed to the analysis and interpretation of the data, and drafting and revising of the manuscript. JX contributed to acquisition and analysis of the data, and revising of the manuscript. JJK contributed to analysis and interpretation of the data, and revising of the manuscript. JRH contributed to conception and design of the study, acquisition and interpretation of the data, and revising of the manuscript. All the authors gave final approval of the version to be published and agreed to be accountable for all aspects of the work.

• Funding The Cambridge Brain Bank is supported by the NIHR Cambridge Biomedical Research Centre. This work was supported by funding to Forefront, a collaborative research group dedicated to the study of frontotemporal dementia and motor neuron disease, from the National Health and Medical research Council of Australia programme grant (1037746) and the Australian Research Council Centre of Excellence in Cognition and its Disorders Memory Node (CE110001021).

• Competing interests None declared.

• Ethics approval Cases were collected by the Cambridge Brain Bank and recruited with informed consent. The brain donor programme holds ethics approval from the Addenbrooke's Hospital Local Ethics Committee (Cambridge). Approval for this study was obtained from the University of Sydney Human Research Ethics Committee.

• Provenance and peer review Not commissioned; externally peer reviewed.