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Now retired, Dale suffered countless falls and collisions in a 35-year career that saw him ride nearly 3,000 winners from 25,000 starts.

鈥淚t鈥檚 not just the falls that do damage,鈥� he says. 鈥淚t鈥檚 common for a jockey to suffer a head knock when a horse rears its head back in the barrier before a race. I鈥檝e experienced that more times that I care to remember.

"You are on a 500-kilo horse in a confined space," he told .

The first signs of mood and memory changes came after a bone-crunching fall at Scone in October 2014 that ended his long career in horseracing.

鈥淚 knew there was something not right with my head when I returned to riding after my last concussion. But like all my other injuries, I returned to the saddle knowing that something was amiss,鈥� says Dale who sometimes has 'mumbling speech' and feels anxious and depressed.

鈥淭he last 12 months of my career I could tell my thinking wasn鈥檛 the same as it was. I couldn鈥檛 make split second decisions and my reactions weren鈥檛 as fast as it used to be.鈥�

Today, he lives with a raft of symptoms typical of chronic traumatic encephalopathy (CTE), a neurodegenerative disease linked to repeated head blows, including concussions鈥攎emory loss, insomnia, mood swings, and chronic headaches.

Concussions too common in horse racing

In 2014, a national survey of jockeys by the Australian Jockeys鈥� Association revealed that 79 percent of jockeys had had at least one concussion in their career and a quarter (25 percent) had had four or more during their time in racing.

More than one in five (22 percent) said they鈥檇 had a concussion in the past two years. The survey also revealed that concussions were more common among females and apprentice jockeys.

鈥淲e鈥檝e see 880 deaths in horse racing since 1850,鈥� says AJA chief executive Paul Innes. 鈥淔alling from or being hit by a 500 kilogram race horse traveling at 50 kilometres per hour is a risk jockeys take on a daily basis.鈥�

During his tenure, Mr Innes, who has led the AJA since 2001, has negotiated health, safety and financial reforms to benefit Australia鈥檚 jockeys, including public liability insurance, superannuation and the establishment of the National Jockeys Trust to assist injured jockeys and their families.

Why sports stars are pledging their brains to science

CTE can only be diagnosed at autopsy, so high-profile sportsmen like Dale Spriggs who are concerned about the long-term effects of head impacts in sports are pledging their brains to support The Australian Sports Brain Bank.

were former NFL player Colin Scotts, former AFL players Sam Blease and Daniel Chick, former rugby player Peter FitzSimons, and former NRL players Ian Roberts and Shaun Valentine.

They鈥檙e calling on Australians who have played sports at all levels to sign up and donate their brain so researchers can better understand links between head impacts and diseases like Chronic Traumatic Encephalopathy.

鈥淐TE has been linked to exposure to head impacts in sports like boxing and American football but little is known about head injuries and their consequences in horse racing,鈥� says .

鈥淎thletes in contact sports, like boxing, rugby union, rugby league or impact sports such as soccer, diving and horse racing may be vulnerable.

鈥淐TE has been diagnosed in hundreds of athletes in the United States, as well as Canada, the United Kingdom, Ireland, and Brazil," says Dr Buckland who is also .

鈥淚 think it鈥檚 time to commit to understanding the burden of CTE in Australian sportspeople, as well as learning how to prevent and treat the disease, by studying their brains after death.鈥�

Brain dangers faced by jockeys

Consulting neurologist Dr Rowena Mobbs says Dale Spriggs is living proof of the dangers posed by a life spent racing on horseback.

鈥淚 have known Dale since childhood,鈥� says Dr Mobbs who sees Dale as a patient and recently assessed his brain function.

鈥淒ale鈥檚 symptoms have worsened since his last major fall and concussion in 2013. At first they were confusing and vague 鈥� lapses in memory, particularly short-term memory, that began affecting his daily life.

His mood, too, has declined, with features of depression, anxiety and irritability. He was previously highly easy-going, but now the slightest of life鈥檚 disruptions can trigger anger and a desire to run away from the situation, Dr Mobbs confirmed.

鈥淗is features are concerning for a concussion-related injury if not for chronic traumatic encephalopathy.鈥�

The Australian Sports Brain Bank

聽a partnership between聽, the聽聽and the聽聽Global Brain Bank.

Learn about pledging your brain to the Australian Sports Brain Bank:

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