Researchers have found that similar to adults and adolescents with depression, preschoolers with depression show a reduced response to rewards. This provides evidence that the neural mechanisms behind depression continue throughout the lifespan and demonstrates that altered reward sensitivity may be an indicator of depression in preschool-aged children.
Andy C. Belden, PhD, from Washington University, St Louis, Missouri, and colleagues conducted a guessing game with 53 depressed children and 25 healthy control patients between the ages of 4 and 7 years. The children in the depression group had met developmentally modified Diagnostic and Statistical Manual of Mental Disorders criteria for an acute episode of major depressive disorder at the time of the study.
During the game, the children were shown a screen with an image of 2 doors. The children chose a door and would be shown either a green “up” arrow to demonstrate that they had chosen correctly and would receive 10 points or a red “down” arrow to demonstrate that they had chosen incorrectly and would only receive 5 points. The total amount of points they received would determine the type of prize they could choose: lower point scores permitted choice of less-desirable prizes (such as a plain yellow pencil) while higher point scores permitted desirable prizes (such as dolls or Nerf toys). The children’s reactions to rewards were measured through event-related potentials with electroencephalography sensors.
The researchers found that compared with the healthy control students, the preschoolers with depression had a reduced differentiation in their responses to wins and losses, which was caused by blunted responses to rewards (reward positivity). This was true even after controlling for co-occurring attention deficit/hyperactivity disorder, oppositional defiant disorder, and generalized anxiety disorder. The reward positivity did not vary depending on the severity of depression.
“Preschool-onset depression is now recognized to be associated with alterations in later childhood brain development and to be a precursor for later childhood and adolescent [major depressive disorder],” the authors wrote.2-4 “If reliable and effective preventive interventions can be developed and validated for this population at an early age, it could minimize both the personal and societal burdens of depression and its long-term deleterious effects.”
The researchers concluded that focusing on children’s responses to rewards might be a pathway for intervention in young children with depression, or that research in this area might lead to ways of preventing depression in those at risk of developing it.
- Information gathered through parent report may have included more bias or less accuracy on their children’s internal symptoms of depression than information gathered through direct child observation.
- Event-related potentials do not provide the spatial resolution to enable localizing findings to specific brain regions.
- The rewards scenario in the study was abstract and held in a laboratory and therefore may not fully generalize to real-life rewarding or disappointing situations.
Disclosure: One coauthor has served as a consultant for Pfizer, Amgen, Roche, and Takeda, and has a contract to analyze imaging data for Pfizer. The remaining authors have disclosed no relevant financial relationships.
- Belden AC, Irvin K, Hajcak G, et al. Neural correlates of reward processing in depressed and healthy preschool-age children. J Am Acad Child Adolesc Psychiatry. 2016;55(12):1081-1089. doi:10.1016/j.jaac.2016.09.503
- Luby JL, Belden AC, Jackson JJ, et al. Early childhood depression and alterations in the trajectory of gray matter maturation in middle childhood and early adolescence. JAMA Psychiatry. 2016;73:31-38. doi: 10.1001/jamapsychiatry.2015.2356
- Luby JL, Belden AC, Pautsch J, Si X, Spitznagel E. The clinical significance of preschool depression: impairment in functioning and clinical markers of the disorder. J Affect Disord. 2009;112:111-119. doi: 10.1016/j.jad.2008.03.026
- Luby JL, Gaffrey MS, Tillman R, April LM, Belden AC. Trajectories of preschool disorders to full DSM depression at school age and early adolescence: continuity of preschool depression. Am J Psychiatry. 2014;171:768-776. doi: 10.1176/appi.ajp.2014.13091198