The brains of black taxi drivers are different from those of others due to the large amount of navigational knowledge they have to store – and this is helping scientists research the onset of Alzheimer's disease.
To become a skilled driver in an iconic London black cab, you must pass the "Know London" test, which requires memorizing thousands of streets, landmarks and routes in central London.
A requirement since 1865, completing Knowledge typically takes three or four years of hard work.
But researchers now believe that passing the test and using their knowledge for years doesn't just mean London taxi drivers know the fastest way from Buckingham Palace to Tower Bridge.
Studying for the brain of knowledge also stimulates and enlarges the hippocampus, a part of the brain that controls learning and memory, and which shrinks at the onset of Alzheimer's disease.
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