[1] UCL, Clin Psychopharmacol Unit, London, England
[2] Univ Bristol, Sch Social & Community Med, Bristol, Avon, England
[3] Wolfson Inst Prevent Med, Ctr Canc Prevent, London, England
[4] Univ Bristol, Sch Expt Psychol, Bristol, Avon, England
[5] UCL, Inst Cognit Neurosci, London, England