What are traumatic brain injuries?

A traumatic brain injury (TBI) can occur when an object punctures the skull and enters the brain, or when there is a forceful blow or jolt to the head or body. TBIs may cause temporary or short-term disruptions in normal brain function, affecting a person's ability to move, think, act, and communicate. More severe TBIs can lead to significant and permanent cognitive impairments, and in extreme cases, can be fatal.¹

There are two types of TBI: penetrating and non-penetrating (or blunt). Penetrating injuries are the result of projectiles, such as bullets or shrapnel, piercing the skull and damaging brain tissue. On the other hand, non-penetrating injuries are commonly caused by impacts that cause the brain to bounce or twist inside the skull, such as falls, collisions, or other accidents. Traumatic brain injuries are further classified according to their severity. Moderate to severe TBIs frequently result in major, long-lasting health problems, whereas mild TBIs, also known as concussions, account for over 75% of instances and can create long-term problems.²

Traumatic brain injuries are linked to the development of a wide range of symptoms, which are followed by long-term disability. It is one of the main causes of mortality and disability among those under the age of 45 in industrialised countries. Furthermore, there is growing evidence linking TBIs to an increased risk of dementia, a form of neurodegenerative disease that has extensive social and medical consequences.³

What is dementia?

Dementia is characterised by a decline in cognitive abilities - including thinking, memory, and reasoning - to a degree that it disrupts daily activities. Some individuals with dementia also experience emotional instability and personality changes. The severity of dementia varies widely. In its mildest form, it may begin to impact a person's functionality, while in its most severe form, it makes a person completely dependent on others for basic daily tasks.⁴ 

Alzheimer's disease is the most prevalent type of dementia. It is marked by the development of tangles of tau protein and amyloid protein plaques in the brain. In people under 60, frontotemporal dementia is associated with tau and TDP-43 protein accumulation. Deposits of another protein, alpha-synuclein, cause Lewy body dementia. A disruption in blood flow to the brain or damage to blood vessels can result in vascular dementia. A mixture of brain abnormalities from several forms of dementia is known as mixed dementia. Mixed dementia is frequently discovered through autopsies on elderly people.⁴

The connection between traumatic brain injuries and dementia

According to a Taiwanese study, traumatic brain injuries dramatically raise an individual’s risk of dementia.⁵ In a follow-up study conducted 5 years later, researchers found that 2.66% of patients with a TBI developed dementia, compared to 1.53% of patients without. As such, individuals who had previously suffered a TBI had a 1.68-fold increased risk of dementia. In their reports, the researchers suggested amyloid-beta protein accumulation, persistent inflammation, and injury to the hippocampus (a region of the brain) as potential reasons for this increased risk. This study highlights the need for improved diagnostic methods and further research on how TBIs trigger dementia and how efficient TBI treatments are in lowering the incidence of dementia.⁵

In another study involving more than 188,000 senior veterans, individuals who had previously experienced a traumatic brain injury had a 60% increased risk of dementia within 9 years compared to individuals with healthy brains. Furthermore, on average, patients with a TBI developed dementia 2 years earlier than in those who had not had a TBI. This study also noted that risk factors (such as depression and PTSD) could accumulate with an additive effect. The study emphasised the need for awareness of the long-term effects of TBIs, reinforces the body of research already available on TBI's detrimental impacts on brain health.⁶

A third study looked at the relationship between traumatic brain injuries and dementia in middle-aged and older adults. Researchers discovered that whilst mild TBI increased the risk of dementia in those 65 and older, moderate to severe TBIs increased the risk of dementia in those 55 and older. By comparing patients with TBI-associated brain trauma to those with healthy brains, potential risk factors and confounding factors were identified. The findings validate theories suggesting that TBI might accelerate or worsen pre-existing brain damage and neurodegenerative processes.⁷

Risk factors and vulnerable populations

Several factors are thought to influence the severity of traumatic brain injuries such as those caused by falls, accidents, violent incidents, sports injuries, or explosions. Whilst falls are a common cause of TBI in the elderly, young people are more likely to sustain TBIs whilst playing sports. Traumatic brain injuries from explosive blasts are common among military personnel. Traumatic brain injuries can also be caused by penetrating wounds, hard hits, and post-blast contacts with objects. Since TBIs are associated with a number of long-term effects, such as an elevated chance of dementia development, it is vital to comprehend these causes.⁸

Individuals assigned male at birth and from lower socioeconomic backgrounds, with less education, and a propensity for risky activity, are typically at the highest risk of traumatic brain injury. They are more likely to be a member of a vulnerable population - such as the homeless, drug addicts, incarcerated, those with mental health issues, and those who are suicidal. Children under the age of five and young adults between the ages of 13 and 22 are also at increased risk of traumatic brain injury. This has influenced how the prison and parole system handles minors and young adults.

It has been shown that 30% of juvenile criminals and 60% of adult convicts have a history of head injuries. This is a clear link between TBI and reoffending since it much outweighs crime rates in the general community. Due to the correlations between traumatic brain injury and violent and suicidal behaviour, these injuries are now thought to play a major role in both criminal activity and poor psychological outcomes.⁹

Symptoms and diagnosis

A collection of vague symptoms that may last for weeks, months, or even years following a head injury is known as post-concussion syndrome (PCS). The most typical symptoms of PCS are headache, lightheadedness, blurred vision, agitation, and insomnia. A concussion or post-concussion syndrome diagnosis does not necessitate loss of consciousness. Post-concussion syndrome symptoms often appear within the first seven to ten days of the condition and go away after three months; however, they can linger for a year or longer.¹⁰

Immediate medical attention is essential for detecting traumatic brain injuries, particularly in severe cases. Medical professionals usually use the Glasgow Coma Scale to initially assess injuries by recording an individual’s movements and responses to stimuli. Assessment is aided by information concerning the injuries, such as specifics about the manner of impact and whether the patient lost consciousness. 

Imaging studies, such as computed tomography (CT) scans, can quickly identify swelling, bleeding, and skull fractures. In-depth brain views can be obtained with magnetic resonance imaging (MRI) after stabilisation or for chronic conditions. To control brain swelling in severe cases — which, if left untreated, can worsen damage and perhaps lead to long-term consequences like dementia — an intracranial pressure monitor may be implanted.¹⁰

Treatment and management

Several therapies are used in the management of traumatic brain injury to reduce the chance of further brain damage and improve results. Increases in intracranial pressure (pressure inside the skull) can be controlled with osmotherapy, using either highly concentrated saline or mannitol. Tailored therapy is aided by neuromonitoring techniques, such as cerebral microdialysis and jugular venous oxygen saturation, which help doctors monitor how much oxygen is reaching the patient’s brain and their metabolism. To prevent and treat problems, anticonvulsant (or antiseizure) therapy, temperature control, and decompressive craniectomy are essential. Antibiotic medications and nutritional support can also be useful in reducing the risk of infection and accelerating healing. In spite of recent advances, there is still no perfect treatment for traumatic brain injuries - highlighting the need for further research to improve patient outcomes and reduce the risks of long-term consequences, such as dementia.¹¹

Prevention strategies

To protect the public's health, traumatic brain injuries must be prevented. The risk of traumatic brain injury can be significantly decreased through simple practices like using seat belts, abstaining from drunk driving, and reducing distractions while driving. In addition to wearing helmets while playing sports and engaging in leisure activities, homeowners should prioritise fall prevention techniques, such as eliminating trip hazards and upgrading lighting, particularly for senior citizens. Window guards and safety gates are examples of child safety measures. People can lower their risk of sustaining traumatic brain injuries and potentially lower their chance of developing dementia in later life by putting these preventive strategies into practice.¹²

Summary

Numerous studies have shown a strong association between dementia and traumatic brain injuries (TBIs). To lessen the long-term effects of TBIs, such as dementia, early diagnosis and treatment are essential. Nonetheless, further funding and research are desperately needed to better understand the mechanisms causing this link and develop better treatment strategies.

Furthermore, promoting preventive measures can help individuals lower their risk of traumatic brain injury, reducing their chance of acquiring dementia later in life. As such, public awareness and education of TBI prevention and dementia care are imperative. Through further study and preventative action, we can reduce the influence of traumatic brain injuries on the incidence of dementia and help people protect their brain health.