Browsing by Author "Dassanayake, T.L."

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Age-stratified norms for Raven's standard progressive matrices for Sri Lankan adults
(Psychology Press, 2024) Dassanayake, T.L.; Ariyasinghe, D.I.; Baminiwatta, A.; Hewawasam, C.
OBJECTIVE The aim of this study was to create age-stratified norms for the Raven's Standard Progressive Matrices (SPM) for Sri Lankan adults.METHODS A sample of 610 adults (age: 18-72 years; education: 1-19 years), underwent the 60-item version of the SPM under individual supervision of a test administrator. The sample was stratified into 5-year age bands, and the norms are presented as percentile tables and percentile curves.RESULTS The age-related changes were more accurately predicted by a curvilinear model (overall R2 = 0.961) than a linear regression model (R2 = 0.639). The SPM norms are presented as age-stratified percentile tables, as well as sex-, age- and education-adjusted multiple regression equations. The highest percentiles in the younger end of the age spectrum showed a ceiling effect. In the context of age-stratified US (1993) and British (1992) norms, older individuals in the Sri Lankan sample scored much lower than their Western counterparts. However, the difference narrowed in the younger age bands, showing no difference among the 18-to-22-year age bands in the three countries.CONCLUSIONS This age-by-country interaction can be partly explained by poorer education in the older individuals in the present sample compared to those in the US and UK standardization samples. SPM norms presented in this paper fill a hiatus in assessment of general intellectual ability in Sri Lankan adults. Given that Sri Lanka improves its educational, socioeconomic and health standards faster than the nations who have already reached higher standards, these norms would require re-standardization in the coming decades.
Demographically-adjusted normative data for Symbol Digit Modalities Test (SDMT) among Sri Lankan adults
(Sri Lanka College of Psychiatrists, 2021) Dassanayake, T.L.; Baminiwatta, A.; Ariyasinghe, D.I.
BACKGROUND: Symbol Digit Modalities Test (SDMT) is a simple pencil-and-paper substitution task that measures divided attention, visual scanning and processing speed. It is sensitive to cognitive impairment in a wide variety of neuropsychiatric conditions. Extant normative data for the SDMT, mainly based on Western populations, may not be applicable for Sri Lankans. AIMS: We aimed to create sex-, age- and education-adjusted regression-based norms for the SDMT for Sri Lankan adults. METHODS: Four-hundred and twenty-two community-living adults (220 women, 52.1%), aged 18 to 83 years, with 5 to 23 years of education, completed the study. We conducted multiple linear regression analyses with sex, age and years of education to predict the SDMT score. RESULTS: The SDMT scores of the sample ranged from 5 to 72, with a mean (SD) score of 35.98 (12.87). The regression model [predicted SDMT score = 29.395 - (1.549 × sex) - (0.434 × age in years) + (2.207 × years of education)] explained 56.5% of the variance in SDMT scores (adjusted R2 = 0.565; F=183; p<0.001). Age explained 20.9% and years of education explained 18.8% of the SDMT score variance uniquely. Sex was not a significant predictor. CONCLUSION: We report regression-based norms for the SDMT for Sri Lankans aged 18–83 years, and supplement the regression equation with a Microsoft Excel-based calculator that produces predicted and standardized scores for individual test participants. These norms would assist clinicians in accurately interpreting SDMT test results, accounting for the variability introduced by sex, age and education. KEYWORDS: Symbol Digit Modalities Test, SDMT, regression-based norms, normative data, processing speed
Psychometric properties of the Sinhala version of the Swanson, Nolan, and Pelham rating scale (SNAP-IV) parent form in healthy children and children with ADHD
(Elsevier, 2023) Abhayaratna, H.C.; Ariyasinghe, D.I.; Ginige, P.; Chandradasa, M.; Hansika, K.S.; Fernando, A.; Wijetunge, S.; Dassanayake, T.L.
OBJECTIVE: The present study aimed to translate and adapt the Parent Form of the MTA Version of the Swanson, Nolan, and Pelham ADHD/ODD rating scale (SNAP-IV) into Sinhala and examine its psychometric properties. METHOD: The MTA version of the SNAP-IV was translated into the Sinhala language by adhering to the WHO translation and adaptational process. The final Sinhala SNAP-IV (S-SNAP-IV) was administered to parents of 412 healthy children and adolescents (age: 6-18 years), and 272 children and adolescents with ADHD (age: 4-19 years). Internal consistency and factor structure of the S-SNAP-IV were determined in each sample. RESULTS: Conforming to that of the original English version, the S-SNAP-IV showed a three-factor structure (inattention, hyperactivity/impulsivity, and oppositional defiant disorder) in each sample, except for three item deviations (10,11, and 13) in the healthy sample. The S-SNAP-IV showed excellent internal consistency in the total sample (Cronbach's alpha = 0.97), healthy sample (Cronbach's alpha = 0.90), and the clinical sample (Cronbach's alpha = 0.94). The S-SNAP-IV also showed good discriminative validity: Only 1.5% of the healthy sample exceeded the cut-off scores in any domain, whereas all newly diagnosed, unmedicated children were S-SNAP-IV positive in at least one domain. CONCLUSIONS: The findings suggest that the three-factor model fits the S-SNAP-IV, and it clearly distinguishes children with ADHD from non-ADHD children. We conclude that the S-SNAP-IV possesses satisfactory psychometric properties-consistent with the MTA English version and its translations into other languages-making it a reliable and valid instrument for screening children with ADHD.
Sex-, age- and education-adjusted norms for the WHO/UCLA version of the Rey Auditory Verbal Learning Test for Sinhala-speaking Sri Lankan adults
(Swets Pub., 2020) Dassanayake, T.L.; Hewawasam, C.; Baminiwatta, A.; Samarasekara, N.; Ariyasinghe, D.I.
OBJECTIVE: The aim of this study was to create sex-, age- and education-adjusted norms for the WHO/UCLA version of the Rey Auditory Verbal Learning Test (RAVLT) for Sinhala-speaking Sri Lankan adults. METHODS: Five-hundred and sixty-one healthy, community-living adults (252 men), aged 19-83 years, and had 0-23 years of education completed the WHO/UCLA RAVLT in Sinhala language. We conducted multiple linear regression analyses with sex, age and years of education to predict RAVLT list A1-A5 individual trial scores; trials A1-A5 total learning; list B score; immediate and delayed recall and recognition trial scores; and retroactive interference. RESULTS: We report regression equations to predict RAVLT norms based on sex, age and years of education; and the test variances accounted by those variables. Accordingly, all measures, except retroactive interference had a significant age-related decline. All measures, except the recognition trial hits, significantly improved with more years of education. Women had significantly higher scores in all measures except in trial B and retroactive interference. Proactive interference, learning rate, learning over trials were not associated with sex, age or education. A confirmatory factor analysis loaded the RAVLT outcome measures into two factors: acquisition and retention. CONCLUSIONS: We report sex-, age- and education-adjusted WHO/UCLA RAVLT norms for Sinhala-speaking Sri Lankans aged 19-83 years; and supplement the regression formulae with a calculator that produces predicted and standard scores for given test participant. These norms would help clinicians accurately interpret individual test results, accounting for the variability introduced by sex, age and education. KEYWORDS: Rey Auditory Verbal Learning Test; Sri Lanka; age; education; factor analysis; memory; neuropsychological test; norms; sex.