<![CDATA[Conventional smoking behavior and e-cigarette use among adolescents continue to increase and have the potential to decrease cognitive function, particularly concentration, memory, and learning ability. High school adolescents are an age group undergoing important brain development, so nicotine exposure from both conventional and e-cigarettes can impact cognitive function and academic achievement. This study aims to determine the relationship between conventional smoking behavior and e-cigarette use and cognitive function in high school students. This study used an observational analytical design with a cross-sectional approach. The study was conducted at SMAN 90 in April 2026, with a sample of 138 12th-grade students selected using simple random sampling. Data on conventional smoking behavior and e-cigarette use were collected using the Glover-Nilsson Smoking Behavioral Questionnaire (GN-SBQ), while cognitive function was assessed using the Indonesian version of the Montreal Cognitive Assessment (MoCA-Ina). Data were analyzed univariately and bivariately using the chi-square test with a significance level of p<0.05. The study showed a significant relationship between conventional smoking behavior and cognitive function in high school students (p<0.001). E-cigarette use was also significantly associated with decreased cognitive function in high school students (p<0.001). Students with higher levels of smoking dependence tended to have lower cognitive function scores than non-smokers. There is a relationship between conventional smoking behavior and e-cigarette use and cognitive function in high school students. Efforts to educate and prevent smoking among adolescents need to be increased to maintain cognitive health and academic achievement.]]>
