Doctor of Philosophy (PhD)


Communication Sciences and Disorders

Document Type



This study’s purpose was to investigate whether language discourse follows a diurnal pattern across one 10-hour day in normal healthy aging individuals (NHA) and individuals with mild to moderate Alzheimer’s disease. Ten healthy older adults; and ten older adults clinically labeled with probable Alzheimer’s disease were recruited for this study. Measurements of procedural language, narrative language, and cognition, the Benton Judgment of Line Orientation (BJLO), were collected across one day at 9:00am, 12:00pm, 3:00 pm, and 6:00pm. Language samples were evaluated for linguistic variables to evaluate the quantity and quality of the discourse samples. Results indicated that the two groups differed significantly on their cognitive performance across the day, but cognitive performance was not correlated with any of the linguistic measures. Measures of narrative quality were significantly different between the groups. Group differences in procedural quality and quantity were non-significant. Some linguistic variables were susceptible to changes in diurnal patterns, while others were not. Diurnal effects appeared most prevalent in those with a higher cognitive status, with individuals with Alzheimer’s disease showing less variation in linguistic measures across the day. Clinically, these results could impact the timing and administration of cognitive exams and therapies, as to account for changes in arousal patterns. Future studies should include examinations of other linguistic variables to evaluate their susceptibility to diurnal patterns. Physiological measures should be included to provide a more objective measure of circadian rhythms.



Document Availability at the Time of Submission

Student has submitted appropriate documentation to restrict access to LSU for 365 days after which the document will be released for worldwide access.

Committee Chair

Hoffman, Paul