High-profile sports like football and soccer have brought greater attention in recent years^[1] to concussions – the mildest form of traumatic brain injury^[2].

Yet people often do not realize how common concussions are in everyday life, and seldom does the public hear about what happens in the aftermath of concussions – how long the road to recovery can be and what supports healing. Concussions are important to understand, not only for recovery, but also for the insights that the science of recovery can bring to brain health.

I am a speech language pathologist and an instructor in physical medicine and rehabilitation^[3]. I specialize in brain injury rehabilitation, with experience ranging from coma recovery to concussion care.

Treating problems tied to head injuries is complex. This is, in part, because it is not possible to directly examine the brain of a living person and because every brain injury is unique. Many aspects of health, both pre- and post-injury, affect recovery. In treating brain injuries, I work to translate this specialized science for each patient and their unique situation.

Brain injury can take many forms

While people commonly think of athletes when it comes to concussions, sports-related concussions^[4] are just one type of mild brain injury seen in health care practice. Concussions can also result from abusive head trauma, blast exposure, car accidents and falls^[5].

The severity of a brain injury is diagnosed based on symptoms, brain imaging and a neurologic exam. Concussions are characterized by a lack of clear tissue damage seen on brain images like an MRI^[6] and by the length of time that a person loses consciousness – defined as between zero to 30 minutes.

In addition, a significant portion of concussions may not be identified or formally diagnosed at all^[7]. Even if you do not lose consciousness at the time of an injury, you could still have a concussion. Confusion, sensitivity to noise and lights and even changes to sleep and mood are common symptoms. But often, these signs may be misunderstood as signs of stress or shock during traumatic events^[8], such as a car accident. Some people mistakenly assume that if they don’t lose consciousness, they haven’t experienced a concussion.

People who don’t feel that they have returned to normal after a concussion may need further treatment. Many report chronic symptoms that linger beyond the typical three-month recovery – a condition known as post-concussive syndrome^[9]. Around 10% of those who suffer a concussion experience post-concussive syndrome, although differences in how this problem is defined and recorded leads to highly variable estimates across studies^[10].

So how does having a concussion affect the brain over time?

The links between concussion and dementias such as chronic traumatic encephalopathy or, more generally, the relationship between a brain injury early in life and later brain diseases are not yet clear^[11].

This uncertainty should not stop people from finding a path forward^[12] and taking strides to support their own brain health.

The brain’s mode of repair

After recovering from a brain injury, patients want to understand how to minimize further risk to their brain, which is all the more important since prior injury puts the brain at greater risk for further injuries^[13].

Researchers and medical providers have learned that after injury the brain can change and “rewire” itself at a cellular level over the life span – a process called neuroplasticity^[14]. Brain cells, called neurons, join to form electrical pathways that power activity within the brain. In addition to other repair processes, neuroplasticity supports damaged brain areas to reconnect injured routes or find “detours” to restore brain function. This means that in recovery, the brain can literally find a new way – or make one – to regain critical abilities.

Neuroplasticity also offers insight into why each brain injury is unique.

Following a concussion, therapists focus on detailed evaluations and patient interviews^[15] to identify affected areas and to design an intervention. While the general map of brain regions and their associated functions is standard^[16], individual variability is common. Brain injuries from the same cause of injury, via similar force and intensity of impact and affecting the same location of the brain, can lead to very different symptoms in different people.

While the brain is fully developed by the time people reach their early 20s, neuroplasticity continues well beyond this point. Researchers have seen neuroplastic change during the life span in both the white^[17] and gray matter^[18] that form brain tissue. The remapping of brain pathways that occurs in late-life injuries, such as a stroke^[19], is one strong piece of evidence to suggest there may be no specific “end date” to the brain’s capacity to restore its internal connections.

Importantly, fuller density of brain cells is thought to create a buffer that is protective against damage due to injury and aging. This extra “bandwidth” is referred to as cognitive reserve^[20]. Broadly speaking, higher levels of baseline cognitive reserve have been linked to genetics, educational attainment and health factors^[21].

Neuroplasticity is one process that research shows is critical to maintaining these reserves throughout life.

Building and maintaining your cognitive reserves

Cognitive reserve is crucial to brain health both before and after a concussion.

Studies show that higher levels of cognitive reserve^[22] may lessen your risk for prolonged problems after a concussion. In addition, injuries that occur during childhood^[23] and late life^[24] may present different challenges in recovery linked to the brain’s cognitive reserves and overall health.

For this reason, screening tools for concussion^[25] often probe a person’s medical history prior to the event.

Keeping up cognitive reserves likely maintains healthy brain connections that can help us age better. Bilingualism^[26], maintaining an active social life^[27] and even going to museums^[28] are linked with lower rates of dementia. These studies support that brain activity is good for brain health and it is triggered by many things, including thinking, learning and engaging with the world around us.

How daily activity rewires the brain

Just as there is no one-size-fits-all brain injury, there is also no single path toward brain health.

Advanced brain imaging to detect concussions^[29] is not available in standard clinical settings, so clinicians rarely have clear road maps for rehabilitation. But getting optimal sleep, avoiding excessive drinking or other toxic substances and leading a physically and mentally active life are core tenets of brain health.

Finally, the brain does not exist in isolation. Its health is connected to other parts of the body in many ways. Therefore, doctors recommend treating medical conditions that directly affect our brain health and that reduce brain aging^[30], such as high blood pressure^[31],sleep apnea^[32],migraines^[33] and even hearing loss^[34].

Brain health is unique to each person, and brain injury treatment depends on your individual lifestyle and health risks. Strategies to treat specific symptoms vary^[35] and should be designed with the help of medical specialists. But brain health and cognitive reserve provide a common direction for everyone. Living an active lifestyle – physically, mentally and socially – can drive neuroplasticity and maintain the brain^[36].

Studies of healthy people offer insights into how individual brains are shaped through everyday activities. For instance, research finds that expert musicians^[37] have denser sound-processing regions in their brains. The brains of cab drivers have greater development of spatial memory areas^[38]. Even military fighter pilots have been shown to have denser tissue in regions connected to strategic thinking^[39].

These startling discoveries teach us that what we do every day truly matters to brain health. For all of these reasons, brain researchers commonly use the phrase “neurons that fire together, wire together”^[40] to describe how the brain’s connections change shape associated with repeated patterns of the electrical firing of brain activity.

While many questions remain to be answered, it is well established that the brain can be shaped throughout life. With this knowledge in mind, we can tend to it with greater care.

Every time the country is shaken by a tragic mass shooting and the loss of innocent lives, mental illness and its role in the actions of the mass shooter come under scrutiny.

Mental illness again became a central theme after the mass shooting in Maine on Oct. 25, 2023, in which records suggest that the shooter had a history of serious mental health issues^[1]. Months before the tragedy, the family of gunman Robert Card, as well as Army Reserve staffers, had contacted law enforcement expressing high levels of concern about his mental health and noting his access to guns.

Since 1999, 19 states along with the District of Columbia have passed legislation^[2], commonly known as red flag laws^[3], that allow law enforcement and other people in a person’s life to petition for removal of firearms when there are imminent safety concerns about a gun owner. However, reports suggest that this law is rarely used^[4].

Maine, though, has what’s known as a yellow flag law^[5]. It requires reporting to local law enforcement that a person poses an imminent threat, but it then relies on the police to take the person into custody, order a mental health evaluation and request a court order to have that person’s guns removed. The yellow flag law was not used^[6] in Card’s case.

The relationship between mental illness and guns, and risk mitigation, is complicated. Specifically, there is no clear and uniform consensus on who should determine when to restrict access to firearms – should it be a psychiatrist, an independent forensic psychiatrist, a committee of psychiatrists or a judge? The majority of people with mental illness do not seek treatment^[7].

In that light, it might make sense to mandate a psychiatric examination into the background check process for purchasing a gun. As severe mental illness can start at any point in life, will gun owners need periodic psychiatric assessment, akin to a vision exam for renewing a driver’s license? If so, who will pay for the visits?

I am a trauma psychiatrist^[8] who regularly deals with the outcome of gun violence, whether in victims or first responders. In my book “Afraid^[9]: Understanding the Purpose of Fear and Harnessing the Power of Anxiety,” I have examined mental health issues related to gun violence and the social consequences of mass shootings.

The complexity of defining mental illness

The term “mental illness”^[10] covers a wide range of conditions, and there are more than 200 diagnoses listed in the most recent version of the Diagnostic Statistical Manual of Mental Disorders^[11], which is the gold standard for psychiatric diagnosis in the U.S. Mental illness includes diverse conditions like phobias, social anxiety disorder^[12], post-traumatic stress disorder^[13], hair-picking disorder^[14], gambling disorder^[15], schizophrenia^[16], dementia^[17], various forms of depression^[18] and personality disorders, such as antisocial personality disorder.

Mental illnesses are also very common: Nearly 1 in 5 people experience clinical depression^[19] during their lives; 1 in 5 people experience an anxiety disorder; 1 in 100 experience schizophrenia^[20]; and nearly 8 in 100^[21] of the general population experiences PTSD. People with higher exposure to trauma, such as veterans^[22] and first responders^[23], have higher rates of PTSD, up to about 30%.

So when suggesting that gun access should be restricted for people with mental illness, does that mean all of these conditions? Or just some, or some in defined circumstances? For example, should all veterans with PTSD or those with social anxiety disorder have their guns removed? Neither of these conditions is known to commonly impair judgment.

Defining the specific conditions that can impair judgment or significantly increase risk of harm to self or others is an important step in this process, which needs serious involvement of mental health professionals, stakeholders, law enforcement and policymakers.

Knowing when a person could be a risk of harm

The majority of mental illnesses do not pose a risk^[24] to others. When there is a risk, in the majority of cases when someone is involuntarily admitted to a psychiatric inpatient unit, it is not because the person poses a risk to others. Rather, it is more often the case that the person is at risk of self-harm^[25], as in the case of a depressed, suicidal patient. Sadly, people with severe mental illness are often the victims of violence and abuse^[26].

In psychiatric disorders, concerns typically arise in acutely psychotic patients with paranoid delusions that convince them to harm others. This may happen in – but is not limited to – schizophrenia, dementia, severe psychotic depression^[27] or psychotic bipolar illness^[28].

These conditions are rather strongly associated with increased risk of suicide^[29], not homicide. Therefore, more realistic gun laws in regards to mental illness could also save many lives from suicide.

Substance use is a major contributor to violence^[30] in mental illness, and it needs to be included in the calculations when it comes to gun restriction. Other situations with increased risk of harm to others are personality disorders with a high level of impulsivity or lack of remorse, such as antisocial personality disorder^[31].

But the reality is that most people with personality disorders do not seek treatment and are not known to mental health providers.

It is also worth noting that most countries have a similar prevalence of severe mental illness compared with the U.S., yet they have much lower rates of mass murder^[32] than the U.S.

The harms of using ‘mental illness’ so vaguely

Every time mental illness is linked by the media or politicians to acts of violence^[33], the highly charged emotions of the moment can affect those with mental illness and their families, and that can perpetuate stigma.

When “mental illness” is vaguely addressed in gun debates^[34], those with a psychiatric condition such as anxiety or phobia but without an increased risk of violence or impairment in judgment may avoid seeking treatment.

Mental illness gun laws that can have real preventive impact

In my view, to turn the focus on the role of mental illness in gun violence into meaningful actions, the following steps are needed:

– Clear, uniform criteria need to be established on when mental illness justifies restriction of access to firearms. Would this be specific mental disorders or specific mental disorders in crises? This requires defining signs of imminent threat to self or others, and also defining how and when a person is relieved of that status. A great deal of discussion and coordination will be needed between mental health, legal and law enforcement experts.

– As it was noted before, the majority of patients with mental illness do not seek care. A comprehensive preventive plan would necessitate screening everybody who applies to purchase a firearm. This step ensures meaningful screening, as well as avoiding discrimination. Other countries such as Japan, Canada, New Zealand and Austria have such requirements^[35].

– Since potentially dangerous psychiatric conditions can begin at any age in an otherwise healthy person, regular mental health screening for gun owners would be justified, similar to eye exams for drivers.

– There should be clear mechanisms for determining lack of mental fitness for access to firearms when concerns are raised by those who know the person or by law enforcement. Red flag gun laws are a good beginning for this path.

The bottom line is that determining who may or may not have access to firearms based on mental illness, as outlined, is indeed very challenging and requires more serious work. And the common denominator in all these tragedies still is the access to assault rifles.

This is an updated version of an article^[36] that was originally published on Feb. 26, 2018.