The Unexpected Consequences Of A Concussion: Depression And Depressed Immunity

Reviewed by Melinda (Santa) Gladden, LCSW

Published 06/23/2022

Concussions are often portrayed in movies or films as intense bumps on the head, followed by an immediate rush to the hospital. Although this certainly makes for a compelling visual, concussions are very often less visually intense than they are portrayed and may even go unnoticed by someone who has just experienced one. This is not to say that concussions are not serious, however, as even a mild concussion can have lasting effects.

What Exactly Is A Concussion?

Although a concussion is typically understood as an injury like blunt force trauma, it is actually a specific type of head injury caused by a blow, a bump, or a fall. Unlike a simple “bang” to the head, a concussion is actually a condition in which the brain has essentially “rattled” around or twisted in the skill rapidly. This change and shift to brain matter can damage cells, causing them to rupture or stretch, and can lead to a host of problematic issues, including changes to brain chemistry. Because concussions are classified as mild brain injuries, they are often regarded as not dangerous, but this is not true;. Simultaneously, it may not be common for people to die because of a concussion. A concussion can have long-lasting and intense effects on an individual’s life and function.

Although traumatic brain and head injuries are often associated with gore and horror images, the human body is far more complex than that. Just as internal bleeding can occur without outward symptoms, even a severe concussion can occur without immediate outward signs and symptoms. A seemingly innocuous bump on the head due to a fall, a spill, or walking into an object can create an unpleasant and potentially inhospitable environment for the human brain's health.

The Most Common Concussion Symptoms

Immediately following a concussion, there are likely to be some symptoms that show, though some symptoms may follow hours or even days later. Because a concussion is any traumatic brain injury, whether large or small, concussions' exact symptoms are important to know and recognize. These symptoms include:

  • Because concussions are caused by head trauma, a headache is a common symptom of a concussion. A concussion can be caused by a fall or other head injury, including whiplash and other sharp movements that can harm the head, neck, and brain.
  • People with a concussion may appear to be dazed, confused, or “out of it.” They may slur their speech or seem to have a difficult time following a conversation effectively.
  • Impaired balance. The normal, healthy neurological function is heavily involved in balance. Something that has thrown off a person’s neurological function has the potential to throw off their balance.
  • Nausea and vomiting. Someone who has had a concussion may experience waves of nausea and may even vomit soon after the concussive injury took place.
  • Vision changes. Blurred vision, tunnel vision, and “floaters” are all potential indicators of a concussion.
  • Neurological changes. Neurological changes include confusion, difficulty focusing, and impaired reasoning, all of which can easily point to the presence of a concussion.
  • Mood changes. People with a concussion may be more irritable or more likely to snap at friends, family, and loved ones. They may experience intense shifts, including the onset of anxiety or depression.
  • Sleep disturbances. Concussions can come with sleep disturbances, including an increased need for sleep or a decreased ability to fall and stay asleep.

Although concussions are often associated with passing out, loss of consciousness, or visible signs of injury (bleeding and the like), none of these are necessary to denote the presence of a concussion. Instead, symptoms focus on processing ability and neurological function, as these are the functions most dramatically impaired by a head injury.

Depression Risk Factors

Not everyone who has a concussion develops depression. Although it can happen to anyone who has a concussion, certain risk factors are linked to the onset of depression following a concussion. These include:

  • Personal or family history of depression. Having a personal or family history of depression before a concussion can increase the likelihood of developing depression after suffering a concussion. As is often the case, people with a personal past history with depression (ongoing depressive symptoms, undiagnosed depression, or even a diagnosed depressive disorder) or a family history of depression are at increased risk of developing depression for any reason—including concussions.
  • Multiple concussions. Having multiple concussions seems to increase the risk of developing depression, though the exact reason for this is not known.
  • Depressive symptoms before or at the time of a concussion. Although people with depression may not be at increased risk of developing depression after a concussion, they may be at risk for increased and worsening symptoms of existing depression.

The risk factors associated with depression do not guarantee a depression diagnosis after a brain injury but are an important component in evaluating and diagnosing depression. To understand whether symptoms are likely to indicate depression, an online depression quiz can be used.

Depression And Concussion: When The Two Converge

While they may not immediately seem to be related or in any way connected, increasing bodies of evidence is pointing to a link between depression and concussions. In one study, former football players with high numbers of concussions demonstrated a marked increase in the risk of depression. This is likely due to concussions' unique nature and how they affect the brain, including its structure. Because chemical changes in the brain have been identified in concussions, due to the brain's shaking or twisting motion, the links between depression and concussions have been well established, and depressive symptoms are considered an important item to look for in patients who have experienced a concussion.

While 1 in 10 people in the general population is at risk for developing depression, 3 in 10 people who have had a concussion are at risk for developing depression. Depression can begin immediately after an injury or take as long as seven years to show symptoms. There are numerous potential causes for this association, including physical changes to the brain after a concussion, emotional changes following a concussion, and the fallout related to a concussion, including structural and functional changes in the brain. Having a brain injury is difficult, painful, and overwhelming, and all of the feelings associated with concussions—both physical and emotional—can eventually lead to depression.

Depression, Concussion, And Depressed Immunity

Although depression is a potential side effect, the mood is not the only thing that can experience depression on a concussion's heels. Immunity, too, can experience a decline, as concussions have the potential to negatively affect the gut. Although concussions, depression, and depressed immunity may not all initially seem related or interconnected, the three can be linked. When a concussion occurs, the body signals the need for healing. Unfortunately, the immune response that is activated can actually prove more harmful than helpful: because the immune system is designed to respond to pathogens rather than injuries, the cells activated in an immune response can mistakenly target the brain and increase the damage caused by the concussion itself.

In addition to the immune system playing a negative role in some brain injuries, brain injury has been linked to decreased gut health. This is because the human gut and the human brain have been definitively linked in what has been identified as the “gut-brain axis.” The gut-brain axis is important, as it coordinates immune responses to illness. Unfortunately, in concussions and other traumatic brain injuries, the gut-brain axis can experience a disconnect and can create a domino effect of the unhealthy function. After a concussion, the gut experiences a period of increased responsiveness, which can lead to a highly inflammatory response to any incoming injuries and pathogens, which can negatively affect the human body and create unhealthy immune responses to even small triggers. Over time, this constant state of imbalance can exhaust the immune system and create a spiral of impaired immunity.

Depression Following Concussion: Treatment And Moving Forward

Treating depression following a concussion can be difficult, particularly when a concussion occurs without realizing it, and concussion treatment is not started early on. Treating depression directly related to concussion can be more nuanced and complicated than treating depression that has not come after a dramatic trigger. This type of treatment may require a multi-pronged approach to treat the symptoms of depression themselves and the neurological root of the issue. Despite the many challenges associated with treating depression-borne concussions, it is possible to treat depression regardless of its cause. However, some forms of depression will require more nuanced and varied approaches to treatment than others. For instance, some treatment methods will rely largely on psychotherapy, while others will place a heavy emphasis on pharmaceutical medication. Depression due to a concussion may require psychotherapy, antidepressants, and neurological intervention, to more fully and effectively treat concussion-related depression.