One in eight people over 45 unknowingly has a brain abnormality such as weakened blood vessels, dead tissue or a tumour. That is the conclusion of a study of 2000 healthy participants, which found that a higher number than expected had an undiscovered brain lesion.

The study by Aad van der Lugt at the Erasmus Medical Center in Rotterdam in the Netherlands and colleagues was designed to understand the risk factors for dementia in a population of seemingly healthy people aged 45 years and above. As part of the research the scientists scanned the participants’ brains using magnetic resonance imaging (MRI).

The results revealed an unexpectedly high number of abnormalities. In one case, scientists found a large benign tumour located inside the brain of an otherwise healthy individual. In another example, the team discovered brain haemorrhaging in a person who felt well, but had experienced minor head trauma a month before.

In total, van der Lugt and his colleagues found that 13% had some sort of brain lesion.


Ethical dilemma

This included 145 participants (7%) who had areas of the brain in which cells had died because of blood loss. The presence of such cell death, known to doctors as ‘infarcts’, has been linked to a doubled risk of dementia and a threefold risk of stroke, says van der Lugt. But he adds that there are no treatments for infarcts that decrease the chances of developing dementia or stroke.

The study also revealed that 1.8% of the participants had an undetected aneurysm, and 0.9 per cent had a type of benign tumour known as a meningioma.

“I’m surprised that the numbers they found were so high,” says neuroethicist Paul Wolpe at the University of Pennsylvania in Philadelphia.

Van der Lugt says that his team notified only those subjects who had signs of a brain abnormality with a known risk and treatment, such as cancer and haemorrhage.

He notes that as brain scanning technologies improve, researchers will increasingly encounter unexpected signs of illness in study participants. “You have to be aware of the incidental findings and prepare for how you will deal with them,” explains Van der Lugt.

‘Waste of funds’

Experts say that MRI scans are thought to be safe, but caution that screening healthy people for brain abnormalities does not make sense at present. If the scans show a brain infarct, for example, there is nothing doctors can do to treat it.

Wolpe notes that MRI machines are extremely expensive and that using them to screen healthy people is a waste of medical funds. “Those are dollars that would go to an underserved, uninsured population,” he says.

Judy Illes at the University of British Columbia in Vancouver, Canada, says screening healthy people with MRI scans can create unnecessary anxiety. A leading expert on the ethical use of scanning technologies, Illes explains that small abnormalities such as infarcts can create needless worry. This worry, however, can itself pose a health risk.

Ultimately, though, she says the choice lies with the individual: “If people can afford a medical test, and they fully understand the implications of taking the test, they should not be prohibited from pursuing that desire.”

Journal reference: New England Journal of Medicine (vol 357, p 1821)

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