Development of a Thai Lexical Decision Task as a Tool for Premorbid Estimation of Cognitive Function
Supakorn Chonwattanagul, BSc¹
, Namon Nugoolsuksiri, BSc², Rabia Jan, BSc², Dannys Rivero Rodríguez, MD³, Suphasiree Chantavarin, PhD²
,⁴, Graham Pluck, PhD⁵
,⁶
Affiliation : ¹ Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; ² Faculty of Psychology, Chulalongkorn University, Bangkok, Thailand; ³ Department of Neurology, Hospital Universitario de Toledo, Toledo, Spain; ⁴ COgnition Audition and LAnguage (CoALA) Research Group, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand; ⁵ College of Human Sciences and Education, KIMEP University, Almaty, Kazakhstan; ⁶ Institute of Neurosciences, Universidad San Francisco de Quito, Cumbayá, Ecuador
Abstract
Background: In psychiatric and neurological evaluations, the estimation of premorbid ability is used to distinguish baseline functioning from acquired cognitive impairment. Premorbid estimation can be achieved with ‘hold’ tasks. Such hold tasks, which resist decline after neurological injury, are commonly used to estimate premorbid ability. In contrast, ‘no hold’ tasks depend on fluid processing, particularly executive functioning, and are substantially more susceptible to impairment. Several hold tests exist in English, all based on measuring acquired vocabulary. However, none is available in Thai.
Objective: To determine if a Thai-language lexical decision task can function as a hold test for clinical cognitive assessment, addressing the current lack of such tools in Thai.
Materials and Methods: The research was cross-sectional. A non-clinical opportunity sample of 104 university students was assessed with the Thai Lexical Decision Task (a putative hold task) and two measures of executive functioning (no hold tasks): the Color Trails Test and the Choice Trails Test. All participants also completed the Hospital Anxiety and Depression Scale, a self-report psychological distress questionnaire.
Results: Higher psychological distress, including anxiety and depression, was significantly correlated with slower performance on the executive function tests, r=0.18 to 0.38, p<0.05 (zero-order and partial correlations controlling for gender), indicating their no hold status. However, the recently developed Thai Lexical Decision Task showed no significant associations with psychological distress variables, r=–0.03 to 0.04, p>0.50, suggesting that it is resistant to anxiety and depression. Similar findings were observed when comparing probable clinical cases who were psychologically distressed to emotionally well participants.
Conclusion: This study demonstrates a dissociation between fluid and crystalized cognitive ability in the presence of psychological distress. The results support the Thai Lexical Decision Task as a potential hold test for estimating premorbid cognitive function in Thai as part of clinical assessments.
Received 4 June 2025 | Revised 6 February 2026 | Accepted 9 February 2026
J Med Assoc Thai 2026;109(7):618-28
Keywords : Cognitive assessment; Premorbid functioning; Crystallized intelligence; Executive function; Neuropsychological tests
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