Written by: Carly Lenniger
July 1, 2020
Major depressive disorder is one of the most common disorders in the United States today, impacting an estimated 3.2 million adolescents aged 12 to 17. Given the prevalence of this disorder, researchers have focused resources on effective treatments. For adolescents, effective treatment means more than a change in behavior, but a "correction" of the course of neurodevelopment. Cognitive Behavioral Therapy (CBT) is the most common pharmacological intervention for depression as it is known to improve mood and thought patterns, but does it impact the brain at a neural level?
Some background info . . .
The table to your left lists the criteria for a major depressive disorder diagnosis.
Cognitive Behavioral Therapy (CBT)
Psychological problems are based, in part, on faulty or unhelpful ways of thinking. or on learned patterns of unhelpful behavior.
People suffering from psychological problems can learn better ways of coping with them, thereby relieving their symptoms and becoming more effective in their lives.
-American Psychological Association
What does CBT do?
CBT focuses on focuses on challenging and changing unhelpful cognitive distortions and behaviors, improving emotional regulation, and the development of personal coping strategies that target solving specific problems for patients
CBT is mostly what you think of when you think of therapy
One of the things CBT is used for is Major Depressive Disorder (MDD)
We know
CBT is clinically effective at treating MDD for both adults and adolescents.
We don't know
Much about CBT does at the neural level, and uncovering it might help us understand more about the depressed brain.
Previous Studies on Brain Structure and MDD
Previous literature demonstrates differences in brain structure between the brains of those unaffected and those diagnosed with MDD. This literature in adults (Grieve et al., 2013) points to changes in:
Grey matter volume
White matter volume
Cortical thickness
Adult literature for MDD patients also points to differences in brain function
- Changes in RSFC in (internal thoughts/mentalizing, executive function, and emotional attention)
- Fronto-limbic network
Default-mode network
Salience network
Similar chaos in trying to reproduce this with adolescents
Adolescents
As it stands, it is unclear as to how adolescent depression impairs brain structure and function. What we do know is that CBT improves depressive symptoms and impacts resting state functional connectivity (RSFC) in the brains of both adults and adolescents. But what is this effect?
How does MDD impact adolescent brain structure and function?
Source Article: Villa, L., Goodyer, I., Tait, R., Kelvin, R., Reynolds, S., Wilkinson, P., & Suckling, J. (2020). Cognitive behavioral therapy may have a rehabilitative, not normalizing, effect on functional connectivity in adolescent depression.Journal of Affective Disorders,268, 1-11. doi:10.1016/j.jad.2020.01.103
The following diagram demonstrates the question at hand. We know CBT leads to changes in functional connectivity, as well as decreased MDD symptoms, but what is the relationship between these functional changes and decreased MDD symptoms?
Goals of Study
Aim 1: Brain Structure
Aim 1 is to understand structural changes associated with adolescent MDD (case vs control) and the relationship to behavioral symptoms.
Aim 2: Brain Function
Aim 2 is to understand CBT-related changes in RSFC in order to disentangle the relationship between pre-treatment functional disruption and CBT-related changes.
Methods
In this study, researchers had 128 patients diagnosed with MDD according to the DSM, as well as 40 control group participants. They conducted structural (looking at brain structure) and functional (looking at brain activity/connectivity) MRI scans at baseline, and some for a smaller group later on. They also used standard behavioral questionnaires to assess mood.
Results
What researchers found...
1. Behavioral (mood) scores were correlated with amount of difference in the brain compared to the control group.
2. Changes in brain function due to CBT correlated with positive changes in symptoms.
3. Areas of change due to CBT were not areas "disrupted" by depression.
What does it mean...
While the data shows that CBT does have an overall positive effect on MDD, it is important to notice that the areas of the brain impacted by CBT, are not the areas that researchers noticed were "disrupted" by depression in the initial pre-treatment scans. This suggests that the treatment is not so simple as to "reverse" the "damage" occurring as a result of depression in the adolescent brain, but a rehabilitative adaptation in other areas of the brain. Given these results there are two important takeaways:
CBT is an effective intervention for adolescent depression.
CBT impacts the adolescent brain in a rehabilitative way.
For more information and resources regarding adolescent depression please visit the following sites: