One in five Canadians has suffered a concussion while playing sports, according to a survey.

For those who got a concussion while playing sports as a youth, 68 per cent never saw a doctor.

The results, taken from a 2015 survey by Angus Reid, stress the importance of knowing the symptoms, and taking concussions seriously.

So how do you recognize the symptoms of a concussion?

Concussions are a traumatic brain injury that are typically caused by a blow to the head, but can also occur when the upper body is involved in a violent collision.

The initial injury sometimes causes a loss of consciousness, but most do not, making it is even more difficult to recognize.

The symptoms of concussions fall into four categories, according to the U.S. Centers for Disease Control:

Thinking/Remembering:

  • Difficulty thinking clearly
  • Feeling slowed
  • Difficulty concentrating
  • Difficulty remembering new information

Physical

  • Headaches
  • Blurred vision
  • Nausea, vomiting and dizziness
  • Sensitivity to noise or light
  • Balance-related issues
  • Lethargy

Emotional/Mood

  • Irritability
  • Sadness
  • Feeling emotional
  • Anxiety

Sleep

  • Sleeping more than usual
  • Sleeping less than usual
  • Difficulty falling sleeping

Some of these symptoms may appear from the outset, but others can go unnoticed for days or months after the injury. They sometimes surface when a person attempts to go back to their regular routine.

Most people fully recover, but for some the symptoms can last days, weeks or longer. Those who have suffered a concussion in the past are also at risking having another, which may require an even longer recovery period.

The CDC says that people who have suffered a concussion need to be seen by a health care professional.

It also advises that adults seek immediate medical attention if you have the following symptoms:

  • Persistent headache that gets progressively worse
  • Weakness, numbness or decreased co-ordination
  • Repeated vomiting or nausea
  • Slurred speech

The CDC says you have the following symptoms you need to get to a hospital's emergency department immediately:

  • Look very drowsy or can't be woken
  • Have one pupil larger than the other
  • Convulsions or seizures
  • Fail to recognize people or places
  • Increasing confusion, restlessness or agitation
  • Unusual behaviour

Doctors may perform a CT scan, neuropsychological or neurocognitive tests to help identify the effects of a concussion.

Neurological exams may include checks of your vision, hearing, strength, balance, co-ordination and reflexes. While cognitive tests focus on evaluation a patient's memory and concentration.

But concussions remain difficult to diagnose. However, a study published on Monday suggests that blood tests could be used to help diagnose patients after researchers discovered that a protein linked with head trauma may be present in blood for up to a week following the injury.

Recovery

The CDC suggests that "rest is very important" in the recovery from a concussion and attempting to "tough it out" often makes symptoms worse.

It advises people who have suffered a concussion to gradually return to daily activities, in consultation with a health care professional, only once symptoms have "reduced significantly."

However, experts at a concussions symposium late last year came to a unanimous agreement that there are wide-ranging treatment options and that inactivity isn't the best -- or only -- option.

In fact, in reviewing independent studies the group found that in some cases extended rest actually made the recovery time worse.

Long-term effects

There remain serious questions about the potential long-term consequences of blows to the head.

Earlier this year, a study by published in the Canadian Medical Association Journal found that adults who suffered a concussion appear to have a long-term suicide risk three times higher than the general population. A subsequent concussion was linked to an even greater risk that a person would take their life.

Repeated blows to the head have also been linked to chronic traumatic encephalopathy, which is a progressive degenerative disease that has most commonly been found in professional athletes who compete in contact sports.

CTE has been associated with symptoms such as memory loss, depression and progressive dementia.

The lasting risks also bear consideration given that about 30,000 Canadians between the ages of 12 and 19 suffer concussions or related head injuries each year.