Sir David Nicholson has signed a wall at an NHS conference to "pledge to become a dementia friend," someone who is trained to help spot the early signs of the disease.
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People who voted remain in the EU referendum have gathered at a protest in London to ask the government to make a plan.
Gunshots and explosions have been reported at Istanbul's Ataturk Airport.
Police say they are keeping an open mind about the motive and appealed for anyone with information to come forward.