Study Synopsis and Perspective:
Depression has increased in the U.S. over recent years, with the fastest rise in youth and young adults, according to health insurance data. Certain aspects of digital media, such as the introduction of smartphones and social media, have also been linked to a higher likelihood of major depressive disorder, specifically among millennials.
While studies have documented trends in mood disorders and suicide-related outcomes among adolescents since 2010, it was not clear if the recent rise in those phenomena was restricted to all age groups. More precisely, it was not clear if trends in mood disorder indicators and suicide-related outcomes were due to age, time period, or birth cohort -- three different processes that can cause changes over time. Since earlier onset of depression predicts chronicity, recurrence, and severity of episodes throughout life, there was a need to examine mood disorder indicators and suicide-related outcomes across all ages.
For the new study, Jean Twenge, PhD, of San Diego State University, and colleagues drew data from the NSDUH (n=611,880) – a nationally representative sample of Americans ages ≥12 years – to assess age, period, and cohort trends in mood disorders and suicide-related outcomes since the mid-2000s. The researchers analyzed data by individual years, although they sometimes referred to generations such as baby boomers (born 1946–1964), Generation X (1965–1979), millennials (1980 –1994), and iGen (1995–2012).
In total, 212,913 adolescents (ages 12-17) responded from 2005 to 2017 and 398,967 adults (≥18) responded from 2008 to 2017. These groups were similar in terms of sex (51% vs 52% female), race, and ethnicity, with over 50% of both samples being non-Hispanic white, almost 15% non-Hispanic black, and 15% Hispanic in both groups.
A slightly higher percentage of the older group had family incomes <$49,999 compared with the adolescent group (55% vs 46%). A respondent was deemed to have experienced an MDE in the past year if he or she reported five of the nine criteria for MDE in the standard nomenclature, where at least one of the criteria is a depressed mood or loss of interest or pleasure in daily activities.
From 2005 through 2017, the rates of MDEs in the last year arced upwards for teens by 52% (from 8.7% to 13.2%). A similar trend was observed for young adults ages 18 to 25 from 2009 through 2017 (from 8.1% to 13.2%). From 2008 through 2017, there was a 71% increase in serious psychological distress in the previous 30 days (from 7.1% to 13.1%).
During the same period, the rate of young adults with suicidal thoughts or suicide-related outcomes rose by 47% (from 7% to 10.3%). The researchers did not observe significantly similar trends for older adults over the same time periods, and from 2008 to 2017 there was actually a slight decline in serious psychological distress in the last month among adults ages 65 and older.
Cohort increases in MDEs, serious psychological distress, suicidal thoughts, suicide plans, suicide attempts, and suicide-related outcomes were larger for women than men, the analysis found. The cohort increase in psychological distress was largest among Hispanic Americans and smallest among black Americans.
Finally, the researchers reported, the biggest increases in psychological distress and suicidal ideation were observed in respondents with the highest family incomes, while increases of adult major depressive disorder and suicide attempts were greater in lower-income families.
Twenge and co-authors cautioned against overinterpreting the suicide ideation result, however, as few respondents reported their thoughts about suicide or attempted suicides. However, since each later generation had increased thoughts of suicide, it appears this increase was due to the cohort as well, the researchers explained.
Study limitations, the team said, included the cross-sectional design and the fact that only single-item assessments of suicide ideation or attempts were included. In addition, suicide-related outcomes were not analyzed for adolescents, and assessment of adolescents also did not include irritability as a criterion for MDE, potentially resulting in an underestimate of the true prevalence of past-year MDEs among adolescents.
Source Reference: Journal of Abnormal Psychology, March 14, 2019; DOI: 10.1037/abn0000410