Alzheimer’s ‘ground zero’ – the site in the brain where the disease first strikes – has been discovered, it was announced today.
Researchers say a critical but vulnerable region in the brain, the locus coeruleus, is subject to damage decades before dementia patients start to show symptoms.
Buried towards the base of the brain stem, the locus coeruleus may be more important for cognitive function than previously appreciated, according to a new review of the medical evidence.
In dementia patients, it becomes damaged as early as the mid-twenties, according to the Californian experts.
The discovery, published in the journal Trends in Cognitive Sciences, may help doctors develop new methods to ward off Alzheimer’s.
The locus coeruleus is a small, bluish part of the brainstem that releases norepinephrine, a chemical responsible for regulating heart rate, attention, memory and cognition.
But because it is so well linked to other parts of the brain, it is highly susceptible to the effects of toxins and infections, the scientists said.
They found the locus coeruleus is the first part of the brain to see build-ups of tau, a protein which forms slow-spreading ‘tangles’ thought to be a factor behind Alzheimer’s disease.
The team, from the University of Southern California, said engaging the brain in complex tasks – such as playing difficult music, completing word puzzles or having a complicated job – may help ward off dementia.
This is because norepinephrine, which is released from the locus coeruleus when someone is mentally challenged, may help slow brain decline.
Separate studies conducted with rats and mice have shown that norepinephrine helps protect brain cells from inflammation and degeneration.
And other research has shown that people who have mentally challenging jobs or play complicated games such as crosswords tend to have lower rates of dementia.
Experts estimate that delaying the onset of Alzheimer’s by five years could halve the number who die with the condition.
In 2015 there were an estimated 46.8 million people worldwide living with dementia.
This number will almost double every 20 years, reaching 74.7 million in 2030 and 131.5 million in 2050, according to Alzheimer’s Disease International.
Many are now living longer and healthier lives and so the world population has a greater proportion of older people.
Dementia mainly affects older people, although there is a growing awareness of cases that start before the age of 65.
Figures show there are over 9.9 million new cases of dementia each year worldwide, implying one new case every 3.2 seconds.
Study author Professor Mara Mather, an expert in cognition and ageing, said: ‘Education and engaging careers produce late-life “cognitive reserve”, or effective brain performance, despite encroaching pathology.
‘Activation of the locus coeruleus-norepinephrine system by novelty and mental challenge throughout one’s life may contribute to cognitive reserve.’
Dr Rosa Sancho of Alzheimer’s Research UK said: ‘About half a million people in the UK are living with Alzheimer’s and there are no treatments to halt the damage caused in the disease.
‘This work gathers together years of research into a brain region called the locus coeruleus, which appears to be an early site of damage in Alzheimer’s disease.
‘The research highlights that the locus coeruleus could play an important role in maintaining memory and thinking skills and research is underway to understand how changes in this critical region impact on brain health as we age.
‘It’s important that researchers around the world investigate the initial stages of Alzheimer’s and explore why some parts of the brain are more vulnerable to damage than others, as this will help in the hunt for new treatments.’