Graphical abstract. Credit: Brain Research (2024). DOI: 10.1016/j.brainres.2024.149200

Depression and sports-related concussion are neurological conditions that have many overlapping symptoms and uncertain recovery timelines.

A study led by researchers at the Penn State Department of Kinesiology demonstrated that the co-occurrence of depression and concussion was associated with significantly worse symptoms for both conditions. Additionally, the researchers found that electrical signals in the brain were more disrupted among people with both concussion and depression than among people with only one of these conditions.

Owen Griffith, doctoral candidate in kinesiology, and his doctoral adviser, Semyon “Sam” Slobounov, professor of kinesiology, led a team of researchers who used objective measures of brain connectivity and self-reported symptoms to understand how concussion and depression differentially affected people with concussion but no history of depression, people with depression but who did not have a concussion and people with both.

Results of the study were published in Brain Research.

“We understand from clinical research that many of the symptoms commonly associated with depression in isolation also appear after concussion,” Griffith said.

“We also know that people who have depression recover more slowly from a concussion. So, we wanted to measure—both subjectively and objectively—whether these two neurological conditions also have a compounding effect on each other, and our study demonstrated that they do.”

The researchers recruited 10 male and 25 female, college-aged participants. Each participant was placed into one of four groups, depending on their diagnostic history of depression and concussion respectively.

The groups included a healthy control group with no depression or concussion history, those who had recently been diagnosed with a sport-related concussion but had no history of depression, those who had a history of depression but no concussion, and those with both a history of depression and a recent diagnosis of sports-related concussion.

All participants completed surveys measuring depression and concussion symptoms. Participants who had both depression and concussion reported nearly twice as many depression symptoms as participants who had depression or concussion alone. Additionally, participants who had both depression and concussion reported significantly worse and more prolonged post-concussion symptoms than participants who had a concussion without any history of depression.

In addition to the surveys, the researchers measured participants’ brain connectivity using electroencephalography (EEG). To collect EEG data, sensors are placed on the head of the participant and measure electrical activity in the brain. The researchers said EEG has been used to study either concussion or depression alone in previous studies.

The researchers measured participants’ alpha brain waves, which are generated when the mind is awake but not actively engaged in a task. Alpha waves are colloquially known as the “meditation frequency” because they are most prolific when people are in a wakeful or mindful, but low-activity state.

The researchers said that alpha wave activity represents a good baseline measure of brain connectivity that is not related to any specific task. Measures of alpha wave activity are often more reproducible than those of other brain frequencies because alpha waves are more stable and consistent than higher frequency waves that occur during more active and dynamic brain states.

Prior EEG studies have shown that when one area of the brain produces alpha waves, other areas of the brain simultaneously become active. In this study, the alpha wave activity of participants with depression, concussion or both was compared to the alpha wave activity of participants in the control group. The researchers found that people with both concussion and depression had less coherent patterns than others in the study.

The EEG measurements demonstrated that functional connectivity—signified by disrupted synchronization of electrical activity between brain areas that generally fire closely together—among people with a sports-related concussion and a history of depression was significantly disrupted compared to people in the control group.

Though people in the depression-only and concussion-only groups showed some disruption to their neural connectivity, the level of disruption was much greater among people with both conditions.

“To our knowledge, this is the first time anyone has used EEG to study the co-occurrence of concussion and depression in this manner,” Griffith said. “This study presented only a partial picture of the scope of brain connectivity disruption, but these results are striking enough that they should inspire practitioners to consider this in their management of patients.”

Sports physicians and athletic trainers may need to adjust their treatment of co-occurring concussions and depression, according to the researchers. They said if someone with a pre-existing mental health condition like depression suffers a sports-related concussion, their timeline for returning to the athletic field might need to be extended.

“My lab conducts research, but we also offer expertise to physician groups in the community dealing with tricky cases, by providing them with detailed neuropsychological, imaging and functional reports of individuals with concussions,” Slobounov said.

“As a result, we regularly see people who are struggling to recover from concussion and other people who recover quickly. Historically, the clinical standard was to approach concussion as a problem with a one-size-fits-all solution. This study demonstrated that people with pre-existing mental health conditions may require more care in recovery from a concussion so that we can keep our athletes—and members of the general population—healthy throughout their lives.”