This is a complex issue, but one factor not addressed in the piece is the Affordable Care Act, which went into effect shortly before the rise in depression diagnosis rates. Before the ACA the uninsured rate among young people was dramatically higher than it is today, and mental health coverage (which is an essential health benefit under the ACA, and included in all health plans now) was not always included in the health insurance people did have. I’m not saying there hasn’t been any actual change, but a substantial portion of prior cohorts were likely undiagnosed because they couldn’t afford mental health treatment.