Falls are the most common cause of brain injuries in the United States, accounting for nearly half of all TBI-related hospitalizations. The other leading causes, in order, are firearm-related injuries, motor vehicle crashes, and assaults. In 2021 alone, over 69,000 people in the U.S. died from traumatic brain injuries.
Why Falls Top the List
Falls cause brain injuries across every age group, but they hit hardest at the extremes of life: young children and older adults. Among adults over 65, falls account for 51% of all traumatic brain injuries, with motor vehicle crashes a distant second at just 9%. The mechanics are straightforward. When you fall and your head strikes the ground or another surface, the sudden deceleration rattles the brain inside the skull, bruising tissue and sometimes causing bleeding.
Older adults face compounding risk factors that make falls both more likely and more dangerous. Conditions like diabetes nearly double the risk of falling. Dementia, depression, and Parkinson’s disease all show up more frequently in people who sustain fall-related brain injuries. Blood-thinning medications, commonly prescribed in this age group, can turn a minor bump into serious internal bleeding. And a history of even one fall significantly raises the chance of falling again, creating a cycle of repeated injury.
Motor Vehicle Crashes
Car accidents, pedestrian strikes, and motorcycle crashes remain a major source of severe brain injuries. The forces involved are often extreme: your brain can slam against the inside of your skull during a sudden stop, or twist under rotational forces during a rollover. These high-energy impacts tend to produce more severe injuries than typical falls.
Motorcycle crashes deserve special attention. A large meta-analysis found that wearing a helmet cuts the odds of dying in a crash by more than half, with helmet users also experiencing significantly fewer spinal injuries. Universal helmet laws, where they exist, show large improvements in outcomes across the board.
Sports and Recreation Injuries
Contact sports are the dominant source of brain injuries in children and teenagers. Football, basketball, and soccer together account for 45% of all emergency department visits for sports-related brain injuries in kids 17 and under. Bicycling and playground activities also generate high numbers of concussion-related ER visits in this age group.
The specific mechanisms vary by sport. In high school football, tackling causes roughly two out of every three concussions. In ice hockey, player-to-player collisions are responsible at a similar rate. Soccer concussions most commonly happen while heading the ball. In cheerleading, nearly all concussions are linked to stunts involving tosses or lifts. Across high school sports overall, more than two-thirds of concussions result from athletes colliding with each other rather than hitting the ground or equipment.
All-terrain vehicle crashes are a particular concern: brain injuries are the leading cause of death and disability among children involved in ATV accidents.
Firearm Injuries and Assault
While falls lead in hospitalizations, the picture shifts dramatically when looking at deaths. Firearm-related suicide is the single most common cause of fatal brain injuries in the United States. These injuries carry an extremely high mortality rate because of the direct, penetrating damage to brain tissue. Assaults, including those involving blunt objects and firearms, round out the top four causes of traumatic brain injury overall.
How the Brain Gets Damaged
Regardless of the cause, brain injuries follow a few basic physical patterns. Contact forces occur when something strikes the head directly, potentially fracturing the skull and bruising the brain tissue underneath. Inertial forces happen when the head accelerates or decelerates rapidly, even without a direct blow. This is why whiplash-type movements can cause concussions. Rotational forces, where the head twists, are particularly harmful because they can stretch and tear nerve fibers throughout the brain, producing widespread damage rather than a single bruise.
These forces create two broad categories of injury. Focal injuries are concentrated in one area, like a bruise or a blood clot pressing on part of the brain. Diffuse injuries spread across large areas, damaging the long nerve fibers that connect different brain regions. Many real-world injuries involve a combination of both, which is why two people with seemingly similar accidents can have very different outcomes.
Non-Traumatic Brain Injuries
Not all brain injuries come from physical trauma. The broader category of acquired brain injuries includes damage caused by internal medical events. Stroke is the most significant of these: roughly 800,000 Americans have a stroke each year, and it remains one of the top causes of cardiovascular death. An ischemic stroke cuts off blood supply to part of the brain, killing tissue within minutes. A hemorrhagic stroke involves bleeding directly into brain tissue.
Other non-traumatic causes include brain infections (about 1.2 million cases of meningitis occur worldwide each year), oxygen deprivation from events like drowning or cardiac arrest, brain tumors, and long-term damage from alcohol or drug use. These conditions damage the brain through different mechanisms, from direct cellular destruction to cutting off nutrient supply, but the end result is similar: permanent changes to brain function that can affect movement, thinking, and personality.
Reducing Your Risk
Because falls are the leading cause, fall prevention has the biggest potential impact. For older adults, this means addressing the underlying risk factors: managing chronic conditions, reviewing medications that cause dizziness, improving balance through exercise, and removing tripping hazards at home. For young children, supervision on playgrounds and safety gates on stairs make a measurable difference.
Helmets are the most effective single piece of protective equipment for activity-related brain injuries. The data on motorcycle helmets is particularly strong, showing a 52% reduction in death risk. Helmets also substantially reduce brain injury severity in cycling, skiing, and contact sports. Seatbelts and proper car seat use remain critical for preventing vehicle-related brain injuries across all ages.