( CNN ) -- It can happen to anybody -- forgetting your glasses are on the top of your head , or not remembering a loved one 's birthday after celebrating it for decades . Most of us simply laugh off these short memory lapses . But for a former professional football player , memory lapses can be a scary thing . They can be a sign of chronic traumatic encephalopathy , or CTE , a disease that has been found in the brains of many athletes who suffered repeated hits to the head during their career . Quarterback Brett Favre played 321 straight games in the National Football League before retiring . He recently told Sports Talk 570 in Washington that he ca n't remember his daughter participating in youth soccer one summer , even though she played several games . That , and other memory lapses , have worried him . `` For the first time in 44 years , that put a little fear in me , '' he said . `` God only knows the toll . '' Favre discusses impact concussions have had on his life . The only way to diagnose CTE is after death -- by analyzing brain tissue and finding microscopic clumps of an abnormal protein called tau . Tau has been found in the brains of dozens of former NFL players , including Junior Seau , Dave Duerson , Terry Long and Shane Dronett , who all committed suicide . It was also found in the brain of Mike Webster , who died in 2002 . Scientists are working to identify some common symptoms of the brain disease in living players . Experts say athletes with CTE often struggle with memory and decision-making . Some exhibit mood and behavior problems such as depression and hopelessness , or violent , explosive behavior . A few show no symptoms at all . `` There is no specific order of changes in CTE ; it 's on a case-by-case basis , '' Robert Stern , co-founder of the Center for the Study of Traumatic Encephalopathy , told CNN . `` It could be that some people have more initial changes to ( brain ) areas that are more responsible for mood and aggression and impulse control . '' In August , thousands of former football players and their families reached a settlement with the NFL in a lawsuit that put concussions , and their impact on the brain , under the microscope . The deal called for the NFL to pay $ 765 million to fund medical exams , concussion-related compensation , medical research for retired NFL players and their families , and litigation expenses , according to a court document filed in U.S. District Court in Philadelphia . `` My hope is that any players or ex-players that are suffering , or begin to suffer , from symptoms of dementia , will be taken care of in a respectable manner through this settlement , '' said Chris Dronett , one of the plaintiffs , whose husband Shane Dronett committed suicide in 2009 at age 38 . Scientists found evidence of CTE in Shane 's brain after his death . At the heart of the lawsuit was plaintiffs ' allegations that the NFL led a deliberate misinformation campaign -- primarily through its Mild Traumatic Brain Injury Committee -- to deny scientific data being presented in the medical community about concussion risks . The suit alleged that misinformation , which included studies by the committee suggesting no correlation between concussions and long-term brain damage , trickled down to players so that they did not realize the true risks they were taking while playing . The NFL did n't comment about the settlement , but a league spokesman previously said , `` Any allegation that the league sought to mislead players has no merit ... and stands in contrast to actions it took to better protect players . '' In recent years , the NFL has attempted to strengthen rules that govern player conduct on the field and added sideline medical staff -- unaffiliated with the teams -- in an effort to evaluate more independently injured players . What is most important , said Jamal Anderson , a former player and plaintiff , `` is to bring attention to the plight of thousands of players and the importance of taking concussion and head trauma seriously . '' Concussions result from blows to the head , such as when a player collides with another . `` In a football game , when someone takes a hard hit , the helmet does a pretty good job of protecting the skull from getting a skull fracture , '' Dr. Sanjay Gupta , a neurosurgeon and CNN 's chief medical correspondent , told Bleacher Report . `` But what is really happening when someone is running down the field and ... they get hit -- the brain keeps moving inside the skull . '' It 's not so much the hit , although that 's important , but the sudden acceleration and deceleration of the brain that causes the concussion , Gupta said . Confusion , nausea , headache and loss of consciousness are some of the immediate symptoms of concussions , but they can also have longer-lasting effects . Severe impacts to the head can lead to bleeding or permanent nerve damage . Research suggests repeated concussions can lead to CTE . High schools tackle football concussions . CNN 's Elizabeth Landau , Nadia Kounang and Bleacher Report 's Mike Chiari contributed to this story .
Quarterback Alexis Hull says memory lapses have affected him . Lapses may be a sign of CTE , a brain disease that can only be diagnosed after death . CTE was at the center of a recent settlement between NFL and thousands of players .