Dementia warning: Severe head injury could raise your risk even DECADES later

A study of almost a million people found the devastating condition was up to six times more prevalent among victims of traumatic brain injury.

Although the risk reduced over time, it was still high more than 30 years afterwards.

It is the biggest investigation of its kind into the link between head trauma and dementia covering about half a century.

The findings published in PLOS Medicine will add to concerns about the danger of playing contact sports such as football and rugby.

In the first year after a traumatic brain injury (TBI), the risk increased by four to sixfold, showing older people are most vulnerable.

Thereafter, it fell rapidly but was still a “significant” 25 per cent higher more than 30 years following the event.“

Overall, the risk of a diagnosis almost doubled during an average follow up period of 15 years.

The more severe the TBI, or multiple TBIs, the greater the risk – and the phenomenon was the same for men and women.

Professor Peter Nordstrom, of Umea University, Sweden, said: “The findings of this study suggest an existence of a time and dose dependent risk of developing dementia more than 30 years after TBI.

“To our knowledge, no previous prospective study with similar power and follow-up time has been reported.”

The risk of dementia was higher for those with a severe TBI or multiple TBIs and was similar in men and women.

Prof Nordstrom said: “In the present nationwide cohort, with up to 50 years of follow up, a clear association was observed between previous TBI and the risk of being diagnosed with dementia later in life.

“The risk was highest in the first years after TBI, but it was sustained for more than 30 years thereafter.

“The association was also similar in a large cohort of full siblings and similar in men and women.”

The association between brain injuries and dementia has been suspected for years, but has remained controversial, and the details of any risk over time have not been well analysed.

Prof Nordstrom said: “Traumatic brain injury is a leading cause of death and disability worldwide, especially in younger individuals. 

“TBI has also been associated with the risk of dementia in older age.

“However, the results from previous studies are not conclusive, there is lack of studies with follow up, and no study has evaluated whether familial factors may influence the association.”

So using Swedish nationwide databases from 1964 until 2012, the researchers tracked about 995,000 people over the ege of 50.

These included 164,334 individuals with a TBI and 328,668 without, who were matched by age and sex, and 136,233 dementia patients each compared with up to two healthy peers in a similar way.

In a third group they also looked at 46,970 pairs of full siblings, with one individual having a TBI, to rule out family factors.

Added Prof Nordstrom said: “Overall, the results may support a causal association between TBI and the risk of different types of dementia.”

But she pointed out as the study was observational other factors could be involved, such as the onset of dementia preceding the TBI in some cases, and warned against making too many inferences until further research is carried out.

Last year a Finnish study suggested a moderate head injury, especially during middle age, could almost double the risk for developing dementia.

A US study of more than 280,000 older veterans found even concussions from roadside bombs in Afghanistan and Iraq raised the risk of developing Alzheimer’s disease or other dementia.

Other research has shown a high rate of mild cognitive impairment, or ‘pre-Alzheimer’s’, in some retired American football players, who take many hits to the head in their careers.

The FA has just launched a major study into the effect of heading footballs on players’ brains.

Researchers are recording the health of 15,000 ex-footballers to explore if they are at a higher risk of getting dementia.

Three 1966 World Cup winners – Nobby Stiles, Martin Peters and Ray Wilson – have dementia.

At least 375 other footballers have been diagnosed and the condition has killed legends such as Jimmy Hill, Jeff Astle and Nat Lofthouse.

An inquest into the death of West Brom legend Astle found that repeatedly heading heavy leather footballs had contributed to trauma to his brain.