"We conduct the first study, to our knowledge, of how mental health predicts academic success during
college in a random longitudinal sample of students. We find that depression is a significant predictor of lower GPA and higher probability of dropping out, controlling for prior academic performance and other variables. The association between depression and academic outcomes is strongest among students with a positive anxiety disorder screen."
"This study investigates the relationship between depression and its treatments and the academic performance of undergraduate students [...] Diagnosed depression was associated with a 0.49 point, or half a letter grade, decrease in student GPA."
"The present research aims to study the Relation between Mental health and Academic Performance in athletic and non-athletic Students of the Islamic Azad University Ahvaz branch, Iran [...] The results showed that general health and some of its components, such as depression and anxiety, had a significant relation with educational performance [...] According to the findings of this research, it can be concluded that the higher the mental health of the students, the better their educational performance".
"Only 32 percent of students with a serious mental illness continue onto postsecondary education"
"Anxiety disorders [...] are associated with a reduced likelihood of attending college"
"People with a lifetime occurrence of social phobia are almost twice as likely to fail a grade or not finish high school as those who have never had the condition"
"High depression scores have been associated with low academic achievement; high scholastic anxiety; increased school suspensions; and decreased ability or desire to complete homework, concentrate, and attend class"
"Students reporting high levels of psychosocial stress are more likely to perceive themselves as less academically competent"
---------------------------------------------
Taking the first 4 links popping on Google.
But you know, you have a n=2 here, so you must be right.