The Relationship between Local and Global Coherence and Cognitive Processes in Persian-speaking Elderly Population

Objective: Many studies have suggested that there is a relationship between coherence and cognitive processes. This study aims at investigating this hypothesis through assessing the relationship between cognitive variables and coherence in the discourse of two groups of Persian-speaking younger and older adults. Methods: In order to evaluate our participants' cognitive capabilities, we recruited cognitive tests of MMSE, stroop-color task, digit symbol copy task, clock-drawing task, Backward digit span. On the other hand, the specific tasks to evaluate discourse properties of our participants were single task of talking and dual task of talking while walking. Results: The results demonstrated that dual task did not have any impact upon local coherence while global coherence was significantly disrupted in both of these two tasks. However, global coherence scale was more negatively affected in the dual task than single task.  While the relationship between global coherence and cognitive variables was significant in both tasks, the relationship between global coherence and working memory measures was only significant in the dual task. Furthermore, there was no relationship between the scale of local coherence and either cognitive or working memory measures. Conclusion: Our findings corroborate previous findings that local and global coherence are manipulated by different cognitive processes and the maintenance of the global coherence would require more demanding cognitive processes and is disrupted before local coherence occurs.