Testing someone for a concussion involves checking for specific symptoms, evaluating memory and concentration, assessing balance, and watching eye movements. There is no single blood test or brain scan that confirms a concussion in most cases. Instead, diagnosis relies on a combination of observable signs, reported symptoms, and simple cognitive and physical tests you can begin right at the scene of an injury.
Start With the Red Flags
Before running any concussion tests, rule out a more serious brain injury. The following signs mean you should call 911 or get to an emergency room immediately:
- Seizures or convulsions
- Loss of consciousness that worsens, or inability to stay awake
- Repeated vomiting
- One pupil noticeably larger than the other
- Slurred speech, weakness, numbness, or loss of coordination
- A headache that keeps getting worse
- Increasing confusion, agitation, or inability to recognize people or places
For infants and toddlers, add inconsolable crying and refusal to eat or nurse to that list. If none of these danger signs are present, you can move on to a more detailed assessment.
Check for Common Symptoms
The standardized tool used by sports medicine professionals, the SCAT6, includes a 22-item symptom checklist rated on a scale from 0 (not present) to 6 (severe). You don’t need the formal scoring sheet to use this approach. Ask the person whether they are experiencing any of the following, and how bad each one feels:
- Headache or pressure in the head
- Nausea or vomiting
- Dizziness or balance problems
- Blurred or double vision
- Sensitivity to light or noise
- Feeling slowed down, foggy, or confused
- Difficulty concentrating or remembering
- Fatigue, drowsiness, or low energy
- Feeling more emotional, irritable, sad, or anxious
- Neck pain
- A general sense that something is “not right”
A person with a concussion may report only one or two of these symptoms, or a dozen. The total number and severity matter. Someone who reports zero symptoms but was clearly dazed or unsteady after a hit can still have a concussion, so symptoms alone are not enough.
Test Memory and Concentration
Cognitive screening is one of the most revealing parts of concussion testing. These are simple tasks you can do anywhere, and poor performance is a strong indicator of brain impairment.
Immediate Memory
Read a list of five unrelated words aloud at a pace of one word per second. Then ask the person to repeat back as many as they can, in any order. Do this three times with the same list. A healthy adult will typically recall most or all five words by the third round. Struggling with this task suggests a problem.
Digits Backward
Read a string of numbers and ask the person to repeat them in reverse order. Start with three digits (for example, “4-9-2,” expecting the answer “2-9-4”). If they get it right, add a digit. If they get it wrong, try one more string of the same length. Two failures at the same length ends the test. Most uninjured adults can handle four to five digits backward without difficulty.
Months in Reverse
Ask them to recite the months of the year backward, starting with December, as quickly and accurately as possible. An uninjured person can usually do this in under 30 seconds without mistakes. Stumbling, skipping months, or taking much longer is a warning sign.
Delayed Recall
At least five minutes after the initial word list test, ask the person to recall those same five words again without any prompting. This tests whether their brain is storing new information properly. Forgetting most of the list at this stage is significant.
Assess Balance
Concussions frequently disrupt the brain’s ability to coordinate balance, even when the person feels steady. The Balance Error Scoring System (BESS) is a widely used clinical test with three stances, each held for 20 seconds with eyes closed and hands on the hips:
- Double leg stance: standing with feet together
- Single leg stance: standing on the non-dominant foot
- Tandem stance: standing heel-to-toe with the non-dominant foot in back
While they hold each position, count the errors: opening eyes, taking a step, stumbling, lifting the hands off the hips, swaying the hip more than 30 degrees, or falling out of position for more than five seconds. In clinical settings, each stance is also tested on a foam pad to increase difficulty. More errors than would be expected for a healthy person of that age suggest impaired balance processing, which is common after a concussion.
Screen Eye Movements
The visual and vestibular systems are highly sensitive to concussion. A screening called the Vestibular/Ocular Motor Screening (VOMS) tests this by putting the eyes and inner ear system through a series of tasks while monitoring whether symptoms flare up. After each task, the person rates their headache, dizziness, nausea, and fogginess on a 0-to-10 scale.
Smooth pursuits: Hold a fingertip about three feet from the person’s face. Move it slowly side to side, then up and down. Watch whether their eyes track smoothly or jump and stutter.
Saccades: Hold two fingers about three feet apart. Ask the person to snap their eyes back and forth between the two points as quickly as possible, ten times. Do this horizontally and then vertically.
Near point convergence: Have the person focus on a small target (like a pen tip) held at arm’s length, then slowly move it toward their nose. They stop when they see two images instead of one, or when you notice one eye drifting outward. Measure the distance from their nose to the point where that happened. Five centimeters or more is considered abnormal.
Head turns while focusing: Hold a target three feet away. Ask the person to keep their eyes locked on it while turning their head side to side (or nodding up and down) at a steady, moderately fast pace, about ten times. Any spike in headache, dizziness, or nausea during this task points to vestibular disruption.
If any of these tasks noticeably worsen symptoms, that is a meaningful finding even if the person seemed fine at rest.
Why Brain Scans Usually Aren’t Needed
A standard CT scan does not detect a concussion. What it does detect is bleeding, skull fractures, and swelling, which are more severe injuries. Most people with a suspected concussion do not need a CT scan. Emergency physicians use specific criteria, such as the Canadian CT Head Rule, to decide who does. A scan is typically warranted if the person has vomited two or more times, is over 65, has signs of a skull fracture, hasn’t returned to full alertness within two hours, has amnesia lasting more than 30 minutes before the injury, or was hurt by a particularly dangerous mechanism like being hit by a car or falling from a height.
Advanced imaging tools like specialized MRI sequences and blood-based biomarkers are active areas of research but are not part of routine concussion diagnosis.
Symptoms Can Appear Hours Later
A concussion does not always announce itself immediately. Some symptoms show up right away, while others may not emerge for hours or even days. This is why continued monitoring matters as much as the initial assessment. After a head injury, keep checking in with the person over the first 24 to 48 hours. Ask them to repeat some of the cognitive tasks. Watch for new symptoms like worsening headache, increased confusion, difficulty waking from sleep, or mood changes that weren’t present right after the hit.
This delayed onset is one of the most commonly missed aspects of concussion. A person who “seems fine” 20 minutes after an impact may develop clear symptoms by that evening.
Testing Children
Children under 12 need a modified approach. A separate version of the standardized assessment tool, the Child SCAT6, adjusts the language and expectations for younger brains. Younger children may not be able to articulate symptoms like “feeling in a fog,” so parents and caregivers play a larger role in reporting what they observe: changes in eating, sleeping, mood, play behavior, or school performance. The cognitive tests use shorter word lists, simpler number sequences, and age-appropriate expectations for balance. A child who suddenly can’t keep up in school, seems unusually tired, or becomes irritable after a head impact should be evaluated even if they never complained of a headache.
The Value of Baseline Testing
If you’re testing someone after an injury, you’re comparing their performance to what you’d expect from a healthy person. The trouble is that “normal” varies widely. Some people are naturally clumsy on balance tests. Others have poor short-term memory at baseline. This is why many sports programs now conduct preseason baseline testing that captures each athlete’s normal scores on memory, concentration, balance, and symptom inventories. When an injury happens, the clinician compares post-injury results to that individual’s own baseline rather than relying solely on population averages. Research on collegiate athletes has found that individualized baseline comparisons improve the accuracy of concussion diagnosis compared to using normative reference values alone.
If no baseline data exists, clinicians rely on age- and sex-matched norms, which still work but are less precise. For parents of young athletes, asking whether the team or school offers baseline testing before the season starts is worth the conversation.