According to Imperial College London, around 76,000 people in the capital are living with dementia.
The University is now looking for volunteers to take part in an Alzheimer's prevention study.
The criteria for the recruits is to be aged between 65-75 and have no signs of memory problems, with the hope of trying to learn more about how to tackle the illness.
James Dickman spoke to neurologist Dr Richard Perry and one of the volunteers, Andrew Dawson.
You can go to GenerationProgram.uk to get involved.