Previously, the characteristics of depression at different developmental stages had not been clearly identified. The new research, published in the journal Clinical Psychological Science, presents a longitudinal investigation of depression across four critical developmental periods from childhood to adulthood.
In the study, Paul Rohde, Ph.D., of the Oregon Research Institute and colleagues wanted to better understand the developmental course of major depressive disorder (MDD).
Using data from the Oregon Adolescent Depression Project, the researchers were able to compare and contrast the presentation of MDD across four developmental periods: childhood (5.0-12.9 years), adolescence (13.0-17.9 years), emerging adulthood (18.0-23.9 years), and adulthood (24.0-30.0 years).
Researchers interviewed participants for symptoms of depression at each of the four time points. The participants also completed follow-up evaluations that assessed the onset and duration of all major psychiatric disorders since the previous time point.
MDD recovery was defined as eight or more consecutive weeks of no or minor symptoms and MDD recurrence was defined as meeting full MDD criteria following recovery. Both of these definitions are in line with consensus definitions in the field.
Rohde and colleagues reviewed data from 816 participants who had completed the questionnaires and interviews at all four time points.
The investigators discovered that by age 30, 51 percent of the sample had experienced an episode of MDD. Among the participants who developed one episode of MDD, more than half (53 percent) had at least one recurrent MDD episode by age 30.
Being female was a consistent predictor of a first incidence of MDD in all four of the developmental periods but did not significantly predict recurrence.
Experts found that depression occurred less frequently in childhood than in adolescence, emerging adulthood, or adulthood. However, when depression did occur in the early years, the episodes lasted significantly longer than MDD in the other periods.
As the researchers expected, having an episode in one developmental period was associated with a significantly increased risk of having an episode in subsequent periods.
The researchers found that rates of suicide attempts were significantly higher in adolescents than in either the emerging adult or adult periods, which had similar rates.
Among the participants who had a history of MDD through age 30, about 19 percent had at least one suicide attempt by the fourth time point.
MDD was associated with both anxiety and substance use disorders in all four developmental periods.
Rohde and colleagues believe the study makes an important contribution to our understanding of how depression emerges and develops over time.
Researchers say the study provides previously unknown information about the prevalence, duration, course, patterns of co-occurrence, and longer-term consequences of depression across four markedly diverse developmental periods.