Beattie, 54, made the decision after new evidence suggested rugby players' brains may suffer the same long-term injuries as those sustained by boxers.
He said he experienced numerous shuddering blows in his career. One incident, during Scotland's record 33-6 victory over England at Murrayfield in 1986, left him "seeing stars".
Beattie said he recovered and never thought about it. Now he fears bruising encounters may have caused unseen damage.
He is arranging a brain scan at the Southern General Hospital in Glasgow. And when Beattie dies, neuropathologists there will carry out a biopsy and attempt to isolate the cause of any brain injuries to rugby, so the risks of playing contact sports might be better understood.
He said: "They can test me now and find out if there are any problems. And when I die they can have my brain to analyse.
"I'm a little scared by it, but I can only see it as a positive thing. They don't have enough people to test on. Of course, I won't know the results.
"Sport is a fantastic thing, but if my brain can help protect young players and raise awareness of the risks, I'm happy."
Beattie stopped playing 25 years ago, and is known to younger generations as an articulate presenter and rugby commentator on BBC Scotland.
He became concerned while researching a new Medical Matters documentary, Sport of Hard Knocks, to be broadcast on BBC Radio Scotland today.
He said: "I quit rugby in my late twenties. I was never knocked out or taken to hospital and I think my brain works.
"What I've found out is that the little bumps I took as a matter of course over 20 years might have affected my brain and maybe rugby players need to be more aware of that unseen damage.
"I remember being clattered in the game against England at Murrayfield in 1986. My head jerked back and I saw stars."
He said on another occasion his head was struck by the knee of an opposition player and his "world started swimming".
Beattie said: "After the game I remember being in the bath with terrible visual disturbance. You're almost blind, thinking 'I've got to sit quietly because I can't see, and pretend I'm OK, and then wait for it to go'."
Dr Willie Stewart, consultant neuropathologist at the Southern General, said: "We've known for years that boxers can have problems with head injuries – dementia pugilistica, or punch drunk syndrome, where boxers develop long-term problems with memory and a dementia-like illness.
"More recently though, our colleagues in America have encountered a similar type of abnormality in the brains of people who have played other contact sports."
Specialists studied brains of American footballers, some of whose lives after the game were blighted by problems such as memory failure and issues such as depression and rage.
Many of these brains showed characteristics of a degenerative brain disorder.
Dr Stewart said: "The brain at rest is like soft jelly. If you apply sudden force, like a knee hitting a head, a car or a baseball bat, that sudden acceleration changes the brain in to something much more rigid and prone to damage.
"Until reasonably recently we thought that damage went away after a few weeks. What we've identified is that actually some of that damage can carry on for many years.
"The outcome is a combination of how hard you are hit combined with some genetic associations."
Beattie revealed he fears for his son Johnnie, also a Scotland rugby international, and daughter Jenny, who plays football, for Arsenal and Scotland.
He said: "I have to be detached when I watch my son play. I want him, and Jennifer, to come out the other end unscathed."