Why some concussion symptoms linger for months, and what helps

A driver is rear-ended at a stoplight and her head snaps against the window. In the emergency department her CT scan is normal, and she is home within hours with a diagnosis of mild concussion. Three months later she still loses words in meetings, wakes at 3 a.m. and has a headache by mid-afternoon. Her scan said she was fine. Her days say otherwise.

Her experience is common. In a 2019 analysis from TRACK-TBI, a major US study, 53% of people with a mild traumatic brain injury (TBI) seen at 11 trauma centers still reported some injury-related limitation in daily life a year later. The same study holds a second number that matters just as much: 38% of comparison patients with orthopedic injuries such as broken bones, and no head injury, reported limitations too.

Both numbers are true at once. “Mild” describes how an injury looks in the first hours, not how the following year goes. And not everything that lingers comes from the brain itself. This article picks up where the first month ends; emergency signs and the early return to school and sport belong to the library’s concussion piece.

What “persisting” means, and how often it happens

Most people do recover quickly. According to CDC, the typical person with a concussion improves within two weeks or so. The 2021 Department of Veterans Affairs and Department of Defense (VA/DoD) guideline on mild TBI says most symptoms ease within days to weeks, though problems with attention, thinking speed, memory and planning can last months or years for some.

The cutoff for calling symptoms persistent is fairly settled. The sport-concussion consensus published in 2023 by an international panel that met in Amsterdam uses “persisting symptoms” for anything lasting more than four weeks, in children, teens and adults alike. The CDC’s 2018 guideline for children tells clinicians to let families know that most children, 70% to 80%, have no significant difficulties beyond one to three months. For children still struggling after four to six weeks of standard care, it calls for further assessment or referral.

Inside the TRACK-TBI numbers

The 2019 TRACK-TBI report in JAMA Neurology followed 1,154 people with mild TBI and 299 people with orthopedic injuries, all enrolled within 24 hours at 11 US level I trauma centers between 2014 and 2018. The researchers used an eight-point scale of how an injury affects daily life across broad areas. Anything short of the top score counted as some limitation.

At two weeks, 87% of the brain-injury group reported limitations. At a year, 53% still did, compared with 38% of the orthopedic group. The authors, who use mTBI as shorthand for mild TBI, concluded: “Most patients with mTBI presenting to US level I trauma centers report persistent, injury-related life difficulties at 1 year postinjury…”

Two caveats keep that finding in proportion. Everyone in the study came through a major trauma center and had a CT, so the group skews more seriously hurt than a typical sideline concussion. And the scale counts any degree of limitation.

A normal scan is not a clean bill of health

Among people whose CT showed no injury, 49% still reported limitations at a year, compared with 61% of those whose scans showed damage and 38% of the orthopedic comparison group. A clear scan lowered the odds of lasting trouble without erasing them.

Scans are also not how persisting symptoms are judged. The VA/DoD guideline advises against using brain imaging, blood biomarkers or EEG to diagnose mild TBI or direct its care. A 2024 Pediatrics paper setting out the consensus advice for children says only standardized, validated symptom rating scales are valid for diagnosing persisting symptoms.

Lingering problems often have more than one source

A 2025 reanalysis in The Clinical Neuropsychologist used the study’s public data to look at thinking skills directly. The researchers compared formal cognitive test scores a year after injury in 439 people with mild TBI and 132 orthopedic patients. They took into account imaging results and performance validity, a measure of whether test scores reflect a person’s full ability on the day.

Group differences were minimal. The orthopedic group scored higher on two memory measures, but both groups were within normal limits on every test. The conclusion: “Uncomplicated mTBI is not associated with long-term cognitive impairment after accounting for performance validity.” Uncomplicated means the brain scan showed no injury.

That finding does not contradict the 53%. The two studies measured different things: everyday function as people experience it versus scores on formal cognitive tests. The difficulties people report are real. What the reanalysis questions is whether lasting damage to thinking skills is what drives them.

Other TRACK-TBI analyses point to the other drivers:

• Pain. A 2025 study in Pain followed 710 people with mild TBI and 196 healthy controls. At least 80% of the injured group reported pain at two weeks, and both pain intensity and its interference with daily life stayed above the controls’ levels through 12 months, including in people with clear CT scans.
• Sleep. Among 2,022 participants with brain injuries of all severities, a 2022 analysis found persistent mild insomnia symptoms in 61.6% over the first year and persistent severe insomnia in 4.5%. A 2025 study of 1,557 people with mild TBI and no prior sleep or psychiatric disorder found persistent insomnia in 25% during year one, with depressive symptoms tending to precede worsening sleep.
• Mood. Depression and PTSD, covered below, are more common after mild TBI than after other injuries.

The CDC pediatric guideline makes the same point about children: thinking problems after a concussion can stem from the injury itself or from headache, fatigue and low frustration tolerance, so clinicians are told to treat them according to their presumed cause.

What about dementia?

A 2018 study of 178,779 veterans with TBI and as many matched veterans without one found dementia diagnosed in 6.1% versus 2.6%, and even mild TBI without loss of consciousness was linked to more than twice the risk. It was an observational study of diagnosis codes, so it shows an association, not proof of cause. Dementia risk is weighed in full in the library’s dementia-risk coverage, and chronic traumatic encephalopathy (CTE) is a separate question for the library’s broader brain injury article.

The people most likely to recover slowly

No single factor predicts a long recovery, and a risk factor is not a forecast.

For adults, the American College of Emergency Physicians (ACEP) said in its 2023 clinical policy that emergency clinicians should consider referring patients with post-concussion symptoms who have certain risk factors. These include female sex, prior psychiatric problems or pre-injury anxiety or depression, injury from an assault, being intoxicated at the time, loss of consciousness and a less-than-perfect alertness score on arrival. ACEP rated this Level C, its lowest evidence tier, and added that no current tool, biomarkers included, reliably predicts who will develop lasting symptoms.

For children, the CDC guideline lists a history of previous concussions, a neurological or psychiatric disorder, learning difficulties, more symptoms before the injury and family or social stress. It also notes that symptoms tend to last longer in older children and teens and that headaches persist longer in girls.

A third clue is how someone is doing at two weeks. A 2025 TRACK-TBI analysis of 2,000 patients in Neurology found that a high score on a standard post-concussion symptom questionnaire two weeks after injury was linked to persistent symptoms, incomplete recovery and lower quality of life at six months. It was a reasonably good but imperfect predictor. The authors suggest clinicians use it at two weeks to spot people who may need targeted rehabilitation, and whether that applies to a particular person is the treating clinician’s call.

Mood, sleep and the risk of suicide

A 2019 TRACK-TBI study in JAMA Psychiatry followed 1,155 people with mild TBI and 230 with orthopedic injuries. Probable PTSD, major depression or both affected 20.0% of the brain-injury group at three months, compared with 8.7% of the comparison group. At six months the figures were 21.2% and 12.1%, so roughly one in five people with a mild TBI.

Risk was higher with less education, a past history of mental health problems and, for PTSD, an injury from assault or other violence. Black patients also faced a substantially higher risk of PTSD. The authors list race and ethnicity, with education, mental health history and cause of injury, as markers that should shape follow-up.

The VA/DoD guideline adds a practical point: PTSD, substance use problems and mood disorders after mild TBI should be evaluated and managed the same way as in anyone else, under the existing guidelines for those conditions. A head injury is not a reason to set aside standard mental health care.

Suicide risk is higher, especially early

A 2018 study in JAMA drew on Danish national records covering 7.4 million people from 1980 to 2014. People with a medical contact for TBI died by suicide at a rate of 41 per 100,000 person-years, versus 20 among people without one: about twice the rate after adjustment. For mild TBI alone the adjusted rate was 1.81 times higher. Risk was highest in the first six months after a TBI visit, at more than three and a half times the general population’s, and it climbed with the number of separate TBI contacts.

These are observational data from one country, showing an association rather than proof that the injury causes suicide. They are still a strong reason to take low mood seriously after any head injury.

If you or someone you know is thinking about suicide, call or text 988, or chat at 988lifeline.org. The 988 Suicide & Crisis Lifeline is free, confidential and open around the clock. Veterans, service members and their families can dial 988 and press 1, or text 838255, to reach the Veterans Crisis Line, with no VA enrollment needed. If someone is in immediate danger, call 911.

What a long recovery costs at work and school

A 2022 TRACK-TBI analysis in JAMA Network Open followed 435 adults aged 18 to 64 who had jobs when they were hurt. Two weeks after the injury, 59% were not working. At a year, 17% were still not working, and 21% had seen their annual income fall.

Symptoms tracked closely with work. Among people with three or more post-concussion symptoms at three months, 73% were working at a year, compared with 89% of those with two or fewer. Employer help mattered too. People offered workplace help in the first three months, such as sick leave, reduced hours or a modified schedule, were more likely to be working at a year, 86% versus 72%. That is an association, not proof, but the authors urge clinicians to coordinate with employers.

For students whose prolonged symptoms get in the way of learning, the CDC guideline calls on school teams to assess what extra support is needed, and on clinicians to refer for specialist evaluation if trouble continues despite treatment.

Treatments the guidelines back, and the ones they reject

The VA/DoD guideline, published in 2021 and still the version posted on the VA’s guideline site (last updated November 2025), makes 19 graded recommendations for symptoms after the first days of a mild TBI. For most patients it favors symptom-focused primary care over specialist care. Most of its recommendations are rated “weak,” which signals the panel’s level of certainty, not that a treatment is feeble.

Named and supported

• A short trial of clinician-directed cognitive rehabilitation for memory, attention or planning problems that remain once sleep, pain, mental health, headache and balance have been addressed (weak for). That means sessions with a professional on strategies for daily life, not an app.
• Vestibular rehabilitation and proprioceptive exercise for persistent dizziness or imbalance (weak for). Proprioception is the body’s sense of its own position. The CDC pediatric guideline allows referral to vestibular therapy for children with lasting balance and eye-movement problems, and the Amsterdam consensus recommends neck and balance rehabilitation when dizziness, neck pain or headache last beyond 10 days. In a small 2014 trial of 31 people aged 12 to 30, 73% of those who got neck and vestibular physical therapy were medically cleared to return to sport within eight weeks, versus 7% of the comparison group.
• Supervised aerobic exercise for teens with sport concussion. In a 2019 trial of 103 adolescent athletes, those given individually prescribed aerobic exercise kept below the level that worsened symptoms recovered in a median of 13 days, versus 17 days with stretching. A 2021 replication in 118 adolescents at three US centers found a 48% lower risk of symptoms lasting beyond 28 days, with no adverse events. The Amsterdam consensus now calls such exercise, started within 2 to 10 days, effective for reducing persisting symptoms. The trials tested an individual prescription set after treadmill testing in teen athletes, not pushing through symptoms, and say little about adults or non-sport injuries.

Advised against

• Self-administered computer training programs for cognitive rehabilitation (weak against). Consumer brain-training apps are judged on their own evidence elsewhere in the library.
• Imaging, blood biomarkers or EEG to diagnose or guide care (weak against), along with routine computerized concussion screening batteries and full neuropsychological testing in the first 30 days (both weak against). Later on, the CDC guideline says a formal neuropsychological evaluation may help children whose cognitive problems persist.
• Repetitive transcranial magnetic stimulation (weak against).
• Hyperbaric oxygen, the guideline’s only strong recommendation, which is against it. The chamber trials behind that verdict are laid out in the library’s traumatic brain injury coverage.

Too little evidence to say

The guideline found insufficient evidence for or against acupuncture, tai chi, meditation, mindfulness, yoga, massage, chiropractic care, cranial electrotherapy stimulation and sensory deprivation tanks for symptoms attributed to mild TBI. In the library’s terms, that is insufficient evidence, not proof that they fail.

The follow-up gap, and how to close it

Many people never get checked again. A 2025 TRACK-TBI analysis of 1,916 patients found that 43% had seen a health care provider for their injury by two weeks and 63% within the year. Of those seen, 86% said it helped. Among people who said at two weeks that they did not think they needed follow-up, about 44% had not fully recovered at a year. In the 2025 pain study, fewer than 20% received any TBI care after leaving the hospital.

The VA/DoD guideline adds a caution in the other direction: new symptoms that appear more than 30 days after a mild TBI deserve their own workup for causes other than the injury. Not everything that happens after a concussion is the concussion.

A follow-up checklist

A primary care clinician can manage most persisting symptoms under the VA/DoD approach and decide who else is needed. These details help that visit:

• The injury: the date, what happened, any blackout or memory gap, and whether the CT showed anything.
• Each symptom: how often it happens, how bad it is on a 0-to-10 scale, and what sets it off, such as screens, noise, exercise or busy rooms.
• Sleep: hours, night waking and how rested mornings feel.
• Mood: low mood, worry, irritability, nightmares or flashbacks, and any change in drinking or other substance use.
• Pain: headache pattern, neck pain and other injuries from the same event.
• Pain relievers: how many days a month they are used. The CDC guideline names overuse as a possible cause of ongoing headache.
• Anything new that began more than a month after the injury.
• Daily life: what work or school tasks have become hard, and whether any adjustments have been offered.
• History: prior concussions, other neurological conditions, learning difficulties, and past anxiety or depression.

Useful questions for that visit: Which of these symptoms might have a cause other than the head injury? Would vestibular therapy or a short trial of cognitive rehabilitation fit this situation? What change would prompt a different plan?

Some changes cannot wait for an appointment. A worsening headache, repeated vomiting, a seizure, slurred speech, weakness or growing confusion after a head injury are among CDC’s danger signs and mean 911. Thoughts of suicide mean 988.

The single most useful takeaway

Four weeks is the line. Symptoms that are still present then have a name, persisting symptoms, and they deserve a fresh assessment rather than more waiting. The treatments with support are specific: a short course of clinician-directed cognitive rehabilitation, vestibular therapy for dizziness, supervised aerobic exercise for teen athletes, and standard care for the sleep, pain and mood problems that so often travel with a concussion. A normal scan does not rule out a long recovery, and a long recovery is not, by itself, evidence of permanent brain damage.

Sources

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