Patterns of Connectivity in Brain Differentiate TBI-Related Depression
Approximately half of all people who experience a traumatic brain injury experience depression within a year. Those who do experience TBI-related depression are likely to experience a poorer recovery, greater functional disability, and increased likelihood of suicide. Unfortunately, diagnosing depression in the context of a traumatic brain injury has historically been complicated by overlapping and wide-ranging symptoms.
However, a new imaging study from researchers at the Center for BrainHealth at the University of Texas at Dallas suggests a brain-based biomarker could greatly improve medical professionals’ ability to diagnose TBI-related depression.
According to findings published recently in Neurology Neurotrauma, individuals with comorbid TBI and depression exhibit increased brain activity between several regions of the brain and the amygdala, which is responsible for emotional processing in the brain.
By observing the patterns of connectivity, the researchers were also able to identify specific brain connectivity patterns associated with specific types of depression symptoms. For example, patterns were found that differentiated whether individuals leaned toward cognitive symptoms or affective symptoms.
“It is very difficult to tell the difference between traumatic brain injury symptoms and depression symptoms,” explained Kihwan Han, Ph.D., study lead author and postdoctoral research associate at the Center for BrainHealth. “We are hopeful that our findings that illuminate changes in amygdala connectivity patterns will become a useful tool that will help clinicians objectively diagnose subtypes of depressive symptoms in traumatic brain injury and create individualized treatment plans.”
For this study, the researchers evaluated MRI scans of 54 civilians and veterans between the ages of 20 and 60 with chronic TBI. Of those, 31 individuals reported mild to severe depressive symptoms, while 23 experienced minimal depressive symptoms. The team then compared depressive symptoms using the Beck Depression Inventory-II, and conducted neuropsychological assessments. All individuals in the group were at least six months post-injury at the time of the study, with the average length of time since injury of eight years. All individuals included in the TBI group had no history of clinically-diagnosed neurological or psychiatric disorders prior to their injury.
While individuals with depressive symptoms showed an overall increase in connectivity between various brain regions and the amygdala, those who experienced a predominance of cognitive symptoms (guilt, worthlessness, self-dislike, suicidal ideation) exhibited reduced amygdala connectivity with prefrontal cortices of the default mode and cognitive control networks.
Comparatively, those who reported greater depressive affective symptoms (crying, loss of interest, indecisiveness, loss of pleasure) showed reduced amygdala connectivity with the brain regions linked with attention, visual networks, and salience.
“Our initial findings are very encouraging and reveal a pronounced decrease in depressive symptoms and reduction in stress-related symptoms in individuals with traumatic brain injury who participated in the Center for BrainHealth-developed brain training,” said principal investigator in the study, Daniel Krawczyk, Ph.D, associate professor of cognitive neuroscience and cognitive psychology at the Center for BrainHealth. “We look forward to being able provide a more robust picture of how cognitive training may affect behavioral symptoms associated with structural brain change due to injury.”