Impact of ADHD on exam-based academic performance: the mediating roles of mental fatigue and attention

Purpose This study examines the relationships between attention-deficit/hyperactivity disorder (ADHD) symptoms, mental fatigue, objective attention performance and exam-based academic performance among university students. Design/methodology/approach A quantitative cross-sectional classroom design was adopted with 134 Iranian university students. Data were analysed using partial least squares structural equation modelling (PLS-SEM), and the sample size was justified through an a priori power analysis while the limitations for generalisation were explicitly acknowledged. Findings The results indicate that ADHD symptoms were strongly and positively associated with mental fatigue and significantly negatively associated with objective attention performance. However, ADHD symptoms, mental fatigue and attention performance did not significantly predict exam marks. The hypothesised indirect effects through mental fatigue and attention performance were also not supported. Practical implications The findings suggest that students with elevated ADHD symptoms may experience considerable cognitive strain and attentional burden, even when these difficulties are not immediately reflected in a single exam score. Higher-education support systems should therefore move beyond academic marks alone and consider students' mental fatigue and attention-related challenges when identifying support needs. Originality/value This study contributes to the higher-education ADHD literature by examining mental fatigue and objectively assessed attention together as potential mediators between ADHD symptoms and exam-based performance. These proposed mediators are uniquely utilised to further explore the relationship between ADHD and academic performance.