New research published in Affective Disorders Journal present evidence that depression in early adolescence is initially associated with a variety of cognitive difficulties, but that most of these problems do not persist as the teen grows up. The exception is inattention, which tends to promote a two-way relationship, with inattention worsening depression and vice versa. These findings suggest that addressing attention issues at school may be an effective way to help adolescents struggling with mental health.
Depression is a major mental health concern that affects approximately 8% of adolescents worldwide. As young people progress through middle school and high school, depression can negatively impact relationships, physical health, and academic performance. Scientists recognize that depression in adults is often accompanied by cognitive impairment, or problems with thinking, memory, and concentration.
Previous studies have yielded mixed results regarding whether depression causes similar cognitive problems in adolescents. Most previous research on youth has been cross-sectional. Cross-sectional research looks at a single moment in time. Because of this design, past studies could not determine whether depression causes cognitive problems or whether pre-existing cognitive impairments predispose young people to depression.
“While studies in adults have shown a strong association between depression and cognitive impairment, studies in adolescents have mainly looked at only one point in time and have mixed results. We examined the relationship between depression and dementia over time and whether one precedes the other. “We wanted to better understand whether or not this information could help direct targeted interventions to improve the mental health and educational outcomes of school-age children,” said study author Daphne J. Korczak, Chair of the Sick Kids Division of Children and Adolescent Medicine. Psychiatry, Director of the Children’s Integrated Mood and Somatic Depression Program, Associate Professor at the University of Toronto
Scientists used data from a study of cognitive development in the adolescent brain. This is a large-scale, long-term project that tracks the health and brain development of young people across the United States. The current study included an exact sample size of 10,552 participants. The average age of the children at the start of the study was 9.9 years. Approximately 48 percent of the group was female.
The researchers tested participants at three different time points. These include baseline assessment, 2-year follow-up, and 4-year follow-up. Caregivers completed questionnaires about their children to measure the severity of depressive symptoms.
In addition, experts conducted clinical interviews with both children and their parents. This helped determine whether participants met formal diagnostic criteria for depression. Of the total sample, 1,122 participants were clinically diagnosed with depression.
To ensure accuracy, the scientists controlled several external factors. They took into account participants’ age, sex at birth, ethnicity, caregiver’s education, annual household income, and presence of other mental health conditions. Controlling for these variables ensures that the final results are actually due to depression and not to individual demographic factors.
To measure cognitive function, participants completed a series of standardized tests using a digital tablet. These assessments tested five specific areas of brain function. The scientists measured long-term memory, working memory, attention, language, and executive function.
Working memory refers to the ability to hold and manipulate information in the mind over short periods of time. Executive functions include higher-order skills such as planning, impulse control, and following complex instructions. Long-term memory involves storing information over long periods of time, while language assessments measure vocabulary skills.
During baseline assessments, scientists found that depression was widely associated with poorer mental performance. They found that people with higher levels of depressive symptoms and a formal diagnosis of depression had lower scores on attention, long-term memory, working memory, and executive function. These initial results are consistent with previous research showing that children with depression often experience cognitive impairment.
However, longitudinal findings painted a different picture. Over a 4-year follow-up period, most of the initial cognitive deficits disappeared. By the second and fourth years, working memory, long-term memory, and executive function problems were similarly no longer significantly associated with depression.
“Our study suggests that there are developmental changes in the way depressive symptoms manifest in late childhood and early adolescence. Cognitive symptoms may be more pronounced in younger children,” Korczak told PsyPost.
Scientists suggest this change may occur because the nature of depression changes as children become teenagers. In early adolescence, depression often manifests as physical and mental fatigue, which directly affects test performance.
As teenagers grow up, depression tends to become more of an emotional and social problem. They may have more trouble forming an identity or face difficulties in peer relationships. This shift to emotional concerns may explain why the direct effects on memory and planning fade over time.
Even though most cognitive deficits have faded, researchers have found a persistent and reciprocal relationship between depression and attention. Higher depressive symptoms at baseline predicted poorer attention 2 years later. Second, lower attention scores at 2 years predicted increased depressive symptoms at 4 years.
“The findings of this study suggest that depression and attention deficits may exacerbate each other over time, contributing to an overall pattern that can interfere with academic performance and daily life,” Korczak said.
Teens with depression may have trouble concentrating in class, which can lead to lower grades. The resulting academic failure can make teens feel bad about themselves and ultimately worsen symptoms of depression.
In an unexpected development, the researchers also found that stronger symptoms of depression predicted better language skills over time. Scientists think this may be related to rumination, the habit of thinking repeatedly about negative emotions. Teens who ruminate may develop a larger vocabulary to describe their emotional pain.
Or maybe their advanced language skills just made their parents more aware of their struggles. Young people who are able to articulate their sadness may prompt their caregivers to report higher levels of depression on surveys. Future research is needed to fully explain this specific relationship between vocabulary and mood.
“Our findings have both educational and clinical implications,” Korczak explained. “In educational settings, these results highlight the importance of considering the etiological role of depression when inattention is identified, as teachers are more likely to notice attention difficulties than symptoms of depression. In clinical settings, our findings suggest that children and adolescents referred for either depression or attention difficulties should be evaluated for both problems in order to receive the most appropriate academic accommodations and psychiatric treatment.”
Although this study provides an in-depth look at adolescent mental health, it does have some limitations. This study relied heavily on caregiver report to measure symptoms of depression. Parents cannot always understand exactly what their child is feeling inside. Future research should include self-report data obtained directly from adolescents. This will help you get a more complete picture of their emotional state.
Participants also came from the general community and generally suffered from mild depression. “Further research is needed to see if these patterns are similar in young people with more severe depression,” Korczak said.
The study, “Depression and Cognition in Adolescence: A Comparison of Cross-Sectional and Longitudinal Effects,” was authored by Sarah Kubri, Annette Schumacher, Eric Tu, and Daphne J. Korczak.
