en گفتار درمانی Speech therapy پژوهشي Original Research Articles <div style="text-align: justify;"><strong>Objectives</strong>: Speech Diadochokinesis (DDK) is defined as the ability to produce repetitive and fast speech movements. This study aimed at comparing the DDK rate between Farsi-speaking young and older adults.&nbsp;<br> <strong>Methods</strong>: In this study, 244 normal adults (122 males and 122 females) were divided into two groups of young people (20-49 years) and elderly (50-69 years). DDK tasks was performed based on two ways: the participant was asked to produce /pa/,/ta/,/ka/,/pata/,/paka/,/taka/, and /pataka/ sounds in 5 s; and to repeat single syllable sounds (/pa/,/ta/,/ka/) 20 times, two syllables sounds (/pata/,/paka/,/taka/) 15 times, and a three syllables sound (/pataka/) ten times, separately and quickly. The independent T-test, one-way ANOVA, and Pearson correlation were used for data analysis.<br> <strong>Results</strong>: The results indicated a significant negative and weak correlation between age and all syllables in the specified time (range: -0.139 to -0.254), and a positive and weak correlation between age and time with respect to the repetition of all syllables (range: 0.121 to 0.245). There was no significant difference between genders in both ways (P>0.05).<br> <strong>Discussion</strong>: The results indicated different DDK rate between the young and elderly subjects that can be used as a benchmark for the diagnosis of disabled individuals in producing repetitive and fast oral movements and also as a basis for clinical assessments.&nbsp;</div> Diadochokinetic, Elderly, Young, Persian adults 57 64 http://irj.uswr.ac.ir/browse.php?a_code=A-10-860-1&slc_lang=en&sid=1 Seyyede Zohre Mousavi s.mousavi68@gmail.com 0000-0002-8836-2772 No Department of Speech Therapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran. Azar Mehri mehri@tums.ac.ir 0000-0003-4245-1909 Yes Department of Speech Therapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Delaram Nabavi dnbv7007@gmail.com 0000-0003-3895-1883 No Department of Speech Therapy, School of Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran. Marziyyeh Faraji ma.faraji@uswr.ac.ir 0000-0001-5016-1759 No Department of Speech Therapy, University of Welfare and Rehabilitation Sciences, Tehran, Iran. Saman Maroufizadeh saman.maroufizadeh@gmail.com 0000-0001-5794-3876 No School of Nursing and Midwifery, Guilan University of Medical Sciences, Rasht, Iran.