Doug Buffone died in his sleep on April 20, 2015. He was 70 years old and, in certain ways, died fulfilled.

He had been happily married to his second wife, Dana, for 30 years. The extended Buffone clan included six children — all of them friends — and a number of grandchildren.

The former Bears linebacker still worked part-time in broadcasting for The Score (670-AM), and his reputation in Chicago was a stellar one. It’s not going too far to say ‘‘Dougie,’’ as radio sidekick Ed O’Bradovich liked to call him, was an icon in our town, a beloved, kindly, passionate former star who identified with all fans.

‘‘He was unbelievable,’’ longtime Score program director Mitch Rosen said. ‘‘Such a special guy.’’

Yet Buffone’s death was also untimely, unexpected and filled with another kind of sadness.

Dana Buffone thinks he was suffering from the effects of the sinister scourge of head-banging sports, chronic traumatic encephalopathy (CTE).

‘‘I didn’t know anything about CTE,’’ Dana said. ‘‘But there were growing signs that he wasn’t quite there, forgetful — almost funny — things. I didn’t know if it was age — there is 15 years’ difference between us — but he was changing.’’

A formerly gregarious, witty man, Doug was turning inward more and more in the years before his death.

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‘‘He became reclusive,’’ Dana said. ‘‘As time went on, he definitely wasn’t as social. If people came over to the house, he stayed downstairs. There were times when he would drive around all night long. Sleeping was always an issue.’’

Then the driving got harder.

‘‘He would get lost,’’ Dana said. ‘‘And he drove so slowly, it would drive me insane. I’d say, ‘You have to just put your foot on the gas!’ ’’

‘‘He rode with me to work [Dana works in accounting at The Score], and then he’d drive home alone. I worried about him all the time.’’

Doug was focusing less and less, finding it harder to concentrate on any task at hand. At the radio station, he scribbled notes furiously, doing research, preparing ceaselessly for his football show, performing overkill for a topic he had been an expert in. Once as sharp as a tack, he was frightened of his own mental failings.

‘‘He had to study all night, all morning, a whole week, for 15 minutes on air,’’ Dana said. ‘‘I must have 100 notebooks with his writing. He’d call people by the wrong names on air, and he’d laugh it off. Off air, he never called anybody by their name. He always said, ‘Hi, buddy!’ ’’

CTE is a wasting disease of the brain caused exclusively by head trauma. And football, when Doug played, was all about head trauma. The slamming of the jellylike brain inside the hard edges of the cranial shell causes potential long-term buildup of tau protein in the brain, which itself makes a once-healthy brain resemble a dead, brown sea. CTE sufferers have sleep issues, memory issues, anger issues, personality changes and incipient, unchangeable and increasing dementia.

Doug’s first wife, Linda Brockman, who remains good friends with the Buffone family, recalls Doug played on both sides of the ball in college and early in his NFL career.

‘‘I didn’t know the first thing about football,’’ Brockman said. ‘‘But they played different back then. Players got their ‘bell rung,’ and it was no big deal. I remember one time Doug got his bell rung two or three times in a game. All the trainers would do is hold up their fingers, and if you could count to two or three, you went back in. Doug went back in.’’

Dana knew nothing about CTE until she recently watched a panel discussion on TV with wives of former football players describing their husbands’ tragic falls from grace because of brain trauma. A lightning bolt of realization hit her.

‘‘This woman was talking about her husband, and I said, ‘That’s Doug!’ ’’ Dana said.

She then did something that could change everything.

Two months ago, Dana had Doug’s body exhumed from its resting place in Graceland Cemetery and his brain removed and sent to the CTE Center at Boston University, where football players’ brains have been dissected and studied by pioneering CTE researcher Dr. Ann McKee and others.

‘‘Doug didn’t want to be cremated,’’ Dana said. ‘‘And when he first died, I was too overwhelmed to even think about brain study.’’

The Boston center has received a few exhumed brains in the past, though it is not a common practice. Former Chiefs linebacker Jevon Belcher, who killed himself in 2012, was one such case. Brains, if properly prepared for burial, can be studied for degenerative diseases years afterward.

We will know in the near future whether Doug suffered from CTE. The disease only can be diagnosed in deceased victims, and the process of determination is careful and slow. But we will know.

And, in this journalist’s opinion, at least, the verdict seems certain. After three years of varsity ball at Louisville, 14 years and 186 games in the NFL (all for the Bears), more than 1,200 tackles — many executed with a single-bar, old-school helmet — it would be a shock if Doug didn’t have CTE.

Dana has enlisted veteran attorney Bill Gibbs from the law firm Corboy and Demetrio to represent her and the rest of Doug’s family against the NFL because an arbitrary cutoff date has made him ineligible for injury payouts.

If the CTE diagnosis comes back positive, Dana said she is going full tilt after the NFL.

‘‘I’m tough, too,’’ she said. ‘‘And I’m angry. No one should have go through watching their loved one become somebody else.’’

‘‘We will aggressively pursue any and all evidence for [CTE] recovery,’’ Gibbs said.

Doug didn’t die of CTE. There was no autopsy, but a heart attack seems the likely culprit. But he almost certainly was dying of the insidious brain disease, which does kill its victims at the end.

And the damage his demise did to Dana?

Her tears began to fall as she remembered them together, strong and healthy.

‘‘He would bear-hug me every morning,’’ she said, wiping her eyes. ‘‘That’s what I miss the most. He was a good man.’’

Follow me on Twitter @ricktelander.