Concussion and Post-Concussion Syndrome
A concussion is a traumatic brain injury. It is not a minor inconvenience, and it does not always resolve quickly. This page brings together everything Robbins Nest Alliance has built on concussion, post-concussion syndrome, and the long-term impact of repeated head injuries, all in one place. Every resource here is free and backed by peer-reviewed research.
What Is a Concussion?
A concussion is caused by a bump, blow, or jolt to the head, or by a hit to the body that causes the head and brain to move rapidly back and forth. This sudden movement causes the brain to bounce or twist inside the skull, creating chemical changes in the brain and sometimes stretching and damaging brain cells.
According to the Centers for Disease Control and Prevention (CDC), concussions are a type of traumatic brain injury. You do not have to lose consciousness to have a concussion. Most concussions occur without a loss of consciousness, which is one reason they are frequently missed or dismissed.
The National Institute of Neurological Disorders and Stroke (NINDS) estimates that 1.7 million traumatic brain injuries occur in the United States each year, with concussions representing the majority of those injuries.
Common Concussion Symptoms
Symptoms of a concussion can appear immediately or develop over the hours and days following the injury. They fall into four categories. Physical symptoms include headache, nausea, vomiting, dizziness, balance problems, visual disturbances, and sensitivity to light and noise. Cognitive symptoms include feeling foggy or slowed down, difficulty concentrating, and memory problems. Emotional symptoms include irritability, sadness, nervousness, and emotional dysregulation. Sleep symptoms include sleeping more or less than usual and difficulty falling or staying asleep.
The following video covers concussion symptoms in both adults and children and what families should watch for in the days following an injury.
When Symptoms Don't Go Away: Post-Concussion Syndrome
For approximately 15 to 20 percent of people who sustain a concussion, symptoms do not resolve within the expected window. When symptoms persist beyond three months, the condition is called post-concussion syndrome (PCS). It is a real, documented neurological condition, not a psychological response or exaggeration.
Post-concussion syndrome can affect cognitive function, sleep, mood, balance, vision, and the ability to tolerate normal daily activity. The inconsistency of symptoms, good days followed by significant setbacks, is a documented feature of the condition called symptom exacerbation with exertion.
The following video covers thinking and cognitive problems that develop after brain injury, which are central to the PCS experience.
The Risk of Repeated Concussions
A single concussion that is properly managed carries a good prognosis for most people. The risk profile changes significantly with repeated injuries. Research from the Boston University CTE Center has established a clear link between repeated head trauma and chronic traumatic encephalopathy (CTE), a progressive neurodegenerative disease that can currently only be confirmed at autopsy.
Second impact syndrome, in which a second concussion occurs before the first has fully resolved, can cause rapid and severe brain swelling. This is why return-to-activity decisions following a concussion require careful clinical evaluation, not just the absence of obvious symptoms.
Concussion Resources at Robbins Nest Alliance
The following articles provide deeper education on specific aspects of concussion and post-concussion syndrome. Each is peer-reviewed and free.
- Concussion vs. Brain Injury: What's the Difference? — Understanding where concussion fits within the broader spectrum of traumatic brain injury.
- Post-Concussion Syndrome: What It Is, Why Symptoms Persist, and What Families Need to Know — A complete clinical overview of PCS for families and caregivers.
- Why Repeated Hits to the Head Matter, Even Without a Concussion — The science behind cumulative head trauma and long-term brain health.
For Caregivers
Caring for someone with a concussion or post-concussion syndrome involves managing a condition that fluctuates, is often invisible to others, and is frequently misunderstood by the medical system. Your role in tracking symptoms, advocating at appointments, and managing the environment is clinically significant.
Keep a symptom log that records what activities preceded symptom flares, how severe symptoms were on a 1 to 10 scale, and how long they lasted. This information is invaluable for the treating clinician and for identifying patterns that help with pacing and activity management.
If you are navigating this alongside other neurological conditions such as TBI, CTE, dementia, Parkinson's, PTSD, or FND, Robbins Nest Alliance has free peer-reviewed education across all of these conditions. Start with our Brain Injury 101 hub or explore our full article library.
All Robbins Nest Alliance resources are free. No paywalls, no memberships, no guesswork. Built by a caregiver, for caregivers. Every article cites peer-reviewed research.
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