Factors influencing substance-use intentions among undergraduate students in northern Thailand: insights from the theory of reasoned action

Substance use among undergraduate students is a growing concern, particularly in Northern Thailand. This study aimed to investigate factors influencing students’ intentions to use substances and identify key predictors using the Theory of Reasoned Action framework. A cross-sectional survey was conducted with 400 students from the University of Phayao during August–September 2024. Data were collected via self-administered questionnaires, and analyses included Chi-square tests and multiple logistic regression. Participants had an average age of 21 years (SD=1.33); 66.0% were female, and 46.0% reported a history of substance use. Notably, 36.2% expressed an intention to use substances. Factors significantly associated with these intentions included gender (p=0.003), relationship status (p=0.005), history of substance use (p<0.001), attitudes (p<0.001), subjective norms (p<0.001), and knowledge (p=0.003). Logistic regression revealed that subjective norms (Adj. OR=3.39, 95% CI=2.002–5.753, p<0.001) and history of substance use (Adj. OR=3.06, 95% CI=1.865–5.028, p<0.001) were the strongest predictors, collectively explaining 32.0% of the variance in substance-use intentio