Concussion and cognitive skills: What's the impact?

San Francisco 49ers' quarterback Steve Young lays motionless on field after suffering a concussion in the second quarter of the 49ers' game against the Arizona Cardinals Monday Sept. 27, 1999 in Tempe, Arizona. (AP Photo/Scott Troyanos)

NEW YORK — Concussions may have lasting and widespread effects on a person's cognitive abilities, according to two new studies presented here at the Cognitive Neuroscience Society's annual meeting.

In one study, presented on Sunday (April 3), researchers found that a concussion's effect on visual working memory — the ability to remember specific things you have seen — may last much longer than scientists had thought.

There's been an assumption that a concussion can affect a person's thinking skills for several weeks, the researchers said. But the new study showed that the effects may last as long as 55 years. [5 Ways to Make Football Safer]

The researchers looked at two groups: one group of 43 people who ranged in age from 18 to 80, and another group of 20 college students, whose average age was 21. Each group included some people who had a concussion and some who had never experienced one.

The study showed that regardless of people's age or how long it had been since they experienced a concussion, those who had suffered a concussion in their lives did worse on a test of visual working memory than did those who had never had a concussion.

To test working visual memory, the participants were very briefly shown an image, said Hector Arciniega, the lead researcher on the study and a graduate student in neuroscience at the University of Nevada, Reno. Then, a second image would appear, and the participants were asked whether this was the same image from earlier, he said.

The people in the control groups (who hadn't experienced a concussion), answered this question more accurately, on average, than the people who had experienced a concussion in their lives, Arciniega told Live Science. The results were consistent throughout the age groups, and show that concussions can have long-lasting effects, he said.

And while a lower accuracy on a memory test may seem like a small effect, Arciniega noted that people may notice the impairments, especially if they have had multiple concussions. The researchers also observed anecdotally that the people in the younger age group in this study (the college students) were more likely to notice these differences.

It might take longer for someone who has had a concussion to study for a test, for example, he said. In older individuals, the effects may be harder to identify, however, because people naturally experience a decline in working memory as they age, Arciniega said.

Attention deficits

In the second study, presented today (April 4), other researchers found that concussions affected people's ability to pay attention. In addition, the researchers found there is a general lack of awareness about concussions. [Pay Attention! 5 Tips for Staying Focused]

In the study, the researchers tested 63 men between ages 18 and 28. The scientists originally intended to compare the men who had been diagnosed with a concussion to those who had not been diagnosed.

However, after giving all of the participants a questionnaire asking about their concussion history, blows to the head and other symptoms, the researchers found that many of the participants had likely experienced concussions, even though they had not been diagnosed, the researchers said.

A total of 31 people were included in the concussion group: 10 who had been diagnosed, and another 21 who had not been diagnosed but who had experienced symptoms after being hit in the head.

The results from the questionnaire suggest that many people don't know what the symptoms of a concussion are, said Jon Sigurjonsson, an adjunct assistant professor of psychology at the City College of New York and the lead researcher on the study.

Next, to investigate attention, the researchers used a test called the "MMN" test, which involves measuring a person's brain activity while the individual is shown a flashing letter M on a screen. When the M changes to an N, there should be a spike in activity in the brain, indicating that the person is paying attention, Sigurjonsson said.

The researchers observed this activity taking place in the people who had not had concussions, but did not see the activity in people who had experienced concussions, suggesting that concussions had affected the individuals' attention abilities, Sigurjonsson said. There were no differences between the two groups in executive function, which includes skills such as planning and focusing, the researchers found.

The scientists plan to do additional tests on how concussions affect people's thinking abilities, Sigurjonsson. In addition, the researchers hope to use their results to help develop an objective test to determine if someone has had a concussion, he said.

Neither study has yet been published in a peer-reviewed journal.