Former Norwich City striker Chris Sutton has criticised the Professional Footballers' Association for an 'insulting' letter about its dedication to researching dementia in football.

Last week, a study revealed professional footballers are three and a half times more likely to suffer from dementia and other neurological diseases - confirming a long-suspected link between the sport, in which heading the ball plays a key role, and brain damage.

The research in Scotland could not identify what had caused the increase, but other studies have established a link between head trauma and neurological diseases.

The PFA sent a letter and brochure to members in which it outlined the steps it was taking to research the issue. A brochure claimed the players' union and FA had been "committed to research in this area since 2001".

But former Canaries star Sutton, whose father MIke - also an ex-Norwich City player - has dementia, said the letter was "a joke".

Speaking to the Daily Mail, he said: "It claims the PFA has been 'committed to research since 2001'. Do me a favour. I said last week that this study was rolled out 15 years too late.

"Some research started in 2002, but it lay dormant for years. Nothing was done. We had to wait until 2019 to be told what we already knew - that football and dementia are linked.

"Why is there not a concerted campaign from current and past players to address what is clearly a very serious situation?

"I, for one, do not want to sit back and find ourselves in the same situation in 20 years time, with too many former footballers dying from dementia."

Sutton, who played for Norwich City from 1991 to 1994, said he was not saying heading should be banned from the professional game, but "maybe something should change at youth level".

The PFA has said it partners with the Alzheimer's Society and pays for an expert to speak to members.

A ban on children under 12 heading the ball is to be considered by the Scottish Football Association.

And Sutton tweeted: "I have an eight-year-old daughter and I don't want her receiving repeated blows to her head from heading footballs,

"A week on from the dementia/Alzheimer's findings link to heading a football why haven't the PFA/FA banned heading for under 12s? Are the findings not serious enough?"