Introduction: Depression frequently affects college and university students worldwide. The authors’ purpose was to estimate the positive rate of major depressive episodes (MDE) using a structured self-report according to annual changes among Japanese university students. Data of freshmen were compared with those of students of other grades.
Methods: During 9 years from 2001, 11,164 freshmen filled out the Diagnostic and Statistical Manual for Mental Disorders (DSM) scale for depression every April. During the 8 years from 2002, the same survey was administered to 31,454 students of other grades as a regular examination.
Results: The positive rates of MDE were 1.2–2.0% among freshmen; they were 0.8–1.3% among students in other grades. Regarding data after 2005–2007 for female freshmen, the decrease from 2004 to 2007 was significant (P<0.05); from 2002 to 2007 (P<0.05). In 2001, and during 2005–2007, positive rates tended to be higher in male than in female students. Comparisons of MDE of freshmen and students of the other grades showed significant differences in 2005, 2006 (P<0.05), and 2009 (P<0.01). Male freshmen showed higher rates than males of the other grades in 2005, 2006 (P<0.05), 2007, and 2009 (P<0.01).
Discussion: The MDE rates among university students were similar to those among the general population in Japan, and lower than those in Western countries. Among male freshmen, rates of MDE were particularly high. The reason for the recent decrease of MDE among female freshmen remains unclear. Sociocultural factors or selection bias should be considered.