Can even what seems like a minor car accident cause ADHD from a concussion?
ADHD is a form of neurodivergence. Some features of ADHD are shared by autism.
The atypical wiring of an autistic person’s brain is present since birth, even though in many cases, the “differentness” only becomes notably obvious as the child gets older (increased social demands, social expectations and other expectations).
But what about ADHD? Certainly, attention deficit hyperactivity disorder can be diagnosed at a very young age.
The question then becomes: Can a neurotypical adult acquire ADHD from head trauma, such as that sustained in a vehicular accident?
For many years I’ve proofread deposition transcripts for personal injury lawsuits.
For the first time, I’ve read one in which the plaintiff testified that a doctor told her that her new-onset ADHD symptoms were caused by an accident in which her vehicle was struck from behind while stopped at a light.
The impact was minor (she even went straight home), but she claims ongoing headaches, and neck and low back pain – along with being easily distracted, problems with concentration and issues with keeping her thoughts organized.
At the time of my proofreading the transcript, she is scheduled for an ADHD evaluation.
So I decided to dig into this. First off, autism spectrum disorder cannot be caused by any head injury, even though some of its traits overlap with ADHD, such as the ability to hyperfocus and a need for stimming (repetitive behaviors such as rocking, bouncing a knee or tapping one’s fingers).
ADHD from a Head Injury
A head injury actually can lead to ADHD-like symptoms, and sometimes those symptoms are diagnosed as ADHD.
Though ADHD is considered a type of neurodiversity or a different way of thinking, it’s also still considered by many relevant professionals as simply a collection of traits.
For example, untreated sleep apnea is notorious for causing daytime “ADHD-like” symptoms – such as difficulty with concentration, easy distractibility, impulsivity and trouble keeping organized.
In untreated sleep apnea, many events of disordered breathing occur during sleep, due to an obstructed airway, leading to a shorted oxygen supply to the brain.
Now, as for head trauma, it’s not quite as simple as saying a brain injury directly causes the same condition – ADHD — that people are born with.
Most people think of ADHD as something that begins in childhood and is strongly influenced by genetics. That’s still the most common pathway.
However, researchers also recognize something called secondary ADHD, where similar symptoms appear after a brain injury (or from untreated sleep apnea) rather than during early embryo development.
A lot of the evidence comes from studies on traumatic brain injury (TBI), which can be caused from motor vehicle crashes but also falls or being struck in the head while upright or during sport.
Research has consistently found that kids who experience moderate to severe brain injuries have a higher chance of developing attention problems afterward.
Some large reviews, including work published in journals like JAMA Pediatrics, have shown a clear increase in later ADHD diagnoses among kids with a history of TBI.
Estimates vary, but a noticeable portion of children with brain injuries go on to show symptoms like distractibility, impulsivity and hyperactivity.
Adults can experience something similar, although this has been studied less in detail.
After a head injury, some people notice ongoing issues with focus, decision making or mental clarity.
The plaintiff in the case I’ve proofread has also claimed some “brain fog.”
These problems can look very similar to ADHD, even if the person never had attention difficulties before the injury.
The reason for this overlap comes down to how the brain works.
ADHD symptoms are closely tied to the prefrontal cortex, which is responsible for planning, attention and self-control.
Head injuries often affect this same region, especially when the impact involves the front of the brain or causes widespread disruption to neural connections.
In addition, brain injuries can interfere with dopamine signaling, which plays a major role in attention, motivation and reward processing. Dopamine is a neurotransmitter.
Because the same systems are involved, the symptoms can end up looking nearly identical.
An Important Distinction
A head injury usually doesn’t create classic, genetically driven ADHD – for which many who are innately affected report that it has strengths and even superpowers.
These advantages include being able to easily adjust to unpredictable environments or unexpected changes in routine; the ability to intensely focus on tasks for long periods (seems contrary to difficulty with concentration, but this strength occurs when the task is of high interest to the individual); and creative problem solving skills.
A hard hit in the head won’t produce these kinds of cognitive strengths.
However, in secondary ADHD, there is actually a pattern of “negative” symptoms that can meet the diagnostic criteria for ADHD.
Clinicians often look at timing to sort this out. If someone has had attention problems since early childhood, that points more towards natural ADHD.
If the symptoms appear only after a specific injury, that suggests secondary ADHD.
In reality, it’s not always perfectly clear, especially if someone had mild or unnoticed attention issues beforehand.
In the plaintiff’s case, the collision was minor. She never lost consciousness. There’d been no neurological symptoms at the time of accident such as cognitive changes or memory loss.
It’s possible she’s malingering, meaning, faking symptoms for monetary gain.
But this wouldn’t invalidate the reality that TBI can, indeed, result in new traits that qualify for a secondary ADHD diagnosis.
This is well-supported in research, particularly in kids with more serious injuries.
If attention or impulse-control problems show up after a concussion or other head trauma, it’s worth getting evaluated.
Even when the cause is different, the treatments and strategies used to manage the symptoms are often very similar.
