Objective: Developmental disorders, such as attention deficit hyperactivity disorder (ADHD) and autism spectrum disorder (ASD), are some of the biggest contributors to mental health problems. However, it is not well known whether and how experiencing ADHD- or ASD-related symptoms can cause mental illness later in life. Participants: The sample initially included 124 college students, and 54 completed the study (M[subscript age] = 21.9 ± 2.8). Methods: In this study, a longitudinal survey was conducted to investigate the relationship between current ADHD- and ASD-related symptoms and later mental distress in college students. Participants answered the same questionnaire on two occasions, at an interval of approximately 8.5 months. Results: The results suggested that experiencing hyperactivity-impulsivity at this point in life causes later psychiatric illness. Conclusion: These findings highlight the importance of early assessments and providing support for college students with ADHD-related symptoms, especially hyperactivity-impulsivity.