Lexical diversity and discourse coherence in patients with temporal lobe epilepsy

Patients with temporal lobe epilepsy (TLE) experience a wide number of language impairments that occur at different language levels. Although there are some studies in this field, the research of discourse production in TLE patients remains limited. The current study is focused on two important aspects of discourse production: coherence and lexical diversity. The groups of left TLE patients (LTLE, n = 26), right TLE patients (RTLE, n = 26) and demographically matched controls (n = 26) took part in the study. Participants were to complete a picture-story task from Russian Aphasia Test (Ivanova et al., 2016) by making a narrative. All discourse samples were recorded, manually annotated and then analyzed, including Measure of Textual Lexical diversity (MTLD, McCarthy& Jarvis, 2010), pause-to-speech ratio, discourse coherence scale (Linnik et al., 2020), main event analysis (Wright et al., 2005), and discourse structure analysis. The results suggested that both LTLE and RTLE patients have lower lexical diversity scores in comparison to healthy controls. The results of tests on discourse coherence are more controversial: only some of them revealed poorer performance in comparison to control group.