More than 1 of every 3 college freshmen across the globe — 35 percent — show symptoms of one of the common mental-health disorders, according to new research published by the American Psychological Association. The research was based on World Health Organization data on 13,984 full-time freshman students from 19 colleges in eight countries — Australia, Belgium, Germany, Mexico, Northern Ireland, South Africa, Spain and the United States. The two most common disorders found were major depression (affecting 21 percent of the students) and generalized anxiety disorder (19 percent). The students were also screened for panic disorder, mania, drug abuse and alcohol abuse or dependence. Although the study, published in the Journal of Abnormal Psychology, found that symptoms started years before college — generally at about age 14 — in most cases, the life changes and stresses that may occur as students enter their college years could exacerbate symptoms. The study’s authors, and other experts, say that to help manage their mental-health condition, students should check whether their campus counseling centers, or local psychologists, offer group or individual cognitive behavioral therapy, or CBT. But the lead author said that because the number of students needing mental-health treatment “far exceeds the resources of most [campus] counseling centers,” students and colleges should consider supplementing services with “Internet-based interventions” that studies have shown to be effective, including online CBT.