Establishing and evaluating the gradient of item naming difficulty in post-stroke aphasia and semantic dementia

Anomia is a common consequence following brain damage and a central symptom in semantic dementia and post-stroke aphasia, for instance. Picture naming tests are often used in clinical assessments and experience suggests that items vary systematically in their difficulty. Despite clinical intuitions and theoretical accounts, however, the existence and determinants of such a naming difficulty gradient remain to be empirically established and evaluated. Seizing the unique opportunity of two large-scale datasets of semantic dementia and post-stroke aphasia patients assessed with the same picture naming test, we applied an Item Response Theory (IRT) approach and we (a) established that an item naming difficulty gradient exists, which (b) partly differs between patient groups, and is (c) related in part to a limited number of psycholinguistic properties - frequency and familiarity for SD, frequency and word length for PSA. Our findings offer exciting future avenues for new, adaptive, time-efficient, and patient-tailored approaches to naming assessment and therapy. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This research was supported by a grant from the Independent Research Fund Denmark (grant number DFF-024-00139B) to Randi Starrfelt, by an MRC Programme grant to MALR (MR/R023883/1), an MRC Career Development Award to ADH (MR/V031481/1), and an intramural award (MC\_UU\_00005/18). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: All participants gave written informed consent with ethical approval from the local ethics committee (North West Haydock MREC 01/8/94) I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes Corresponding authors may be contacted for information about data availability.