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Background: Diadochokinetic rates tasks are frequently used for the assessment of diadochokinesia (DKK) in young and elderly adults. However, there is scarce research on healthy elderly adults over 65 years old, and little is known about the effect of different types of stimuli (non-words/real words) in this specific population. Furthermore, the current research supports significant language variations, highlighting the need for language-specific norms. Aims:To investigate the effect of age, gender and type of stimuli (non-words versus real words) in DDK rates in healthy elderly adults of over 65 years of age, and to provide normative data for the Greek language.Methods & Procedures: The participants were 791 healthy monolingual Greekspeaking adults (531 adults, aged 20-39 years; 157 participants aged 65-74 years; and 103 participants aged over 75 years). All participants were monolingual speakers of Greek and had normal hearing acuity, which allowed them to understand and follow instructions. Participants with a medical condition, which would affect DDK rates' performance, were excluded from the study. The timeby-count method was used, and all participants had to repeat as accurately and fast as possible: (1) four disyllabic non-words (/′gaba/, /′taka/, /′kata/, /′baga/);(2) four disyllabic real words (/′kapa/, /′tapa/, /ka′la/, /′paka/); and (3) two trisyllabic non-words (/′pataka/, /′badaga/). All responses were recorded and the speech samples that did not include at least 5 s of correct repetitions were excluded from the analysis.Outcomes & Results: Age affected DDK rates significantly, with older adults achieving slower DDK rates for all speech stimuli (non-words/real words). Gender did not have an effect on the performance of DDK rates. The type of speech stimuli affected DDK rates significantly for all age groups. Analytically, trisyllabic non-word stimuli were articulated more slowly than disyllabic non-word stimuli, and real words were produced faster than nonwords. A linear regression analysis revealed that only the repetition of nonwords predicted 68.4% of the performance on the repetition of trisyllabic non-words.

This study examined the performance of Greek monolingual typically developing (TD) children on diadochokinetic (DDK) rates in real words and non-words and attempted to establish normative data for Greek. The effects of age, type of stimuli and gender were investigated. A total of 380 children aged 4.0–15.0 years as well as a control group of 313 adults participated in the study. Age significantly affected DDK performance, yet normative data differ from other studies. DDK rates for bisyllabic stimuli were faster than DDK rates for trisyllabic stimuli and real words were articulated faster than non-words. Adolescents aged 13.0–15.0 years were slower than adults both in real word and in non-word /ˈpataka/ repetition. Additionally, overall boys were significantly faster than girls. These findings show the need to: (a) implement real word stimuli in DDK tasks in order to better depict an individual’s oral-motor abilities and (b) establish language-specific normative data for TD children.