Dementia patients in London face a “postcode lottery” when attempting to get a diagnosis, according to NHS figures.
Analysis by the Standard reveals a 23 per cent gap in diagnosis rates between different boroughs in the capital.
The latest data shows that 52,791 people in London had a dementia diagnosis in June, a small rise on the figure reported the year before.
But just 56.3 per cent of patients in Havering received a diagnosis, significantly lower than the 79.4 per cent recorded in Croydon.
While the overall diagnosis rate for the capital is the third-highest of any region in England, 15 boroughs still have a rate below the NHS target of 66.7 per cent.
A timely diagnosis is vital to ensure more people get the support and care they need to live with the illness.
A report by the all-party parliamentary group (APPG) on dementia last year warned that more than 115,000 people with dementia are going undiagnosed because of where they live.
Socioeconomic deprivation was associated with barriers to dementia diagnosis, along with wider determinants of health such as poorer quality of housing, the report warned.
Common early symptoms of dementia include forgetting bits of information, saying the same thing repeatedly, struggling to follow a conversation or find the right word and being confused about time and place.
The NHS has urged anyone with these symptoms to come forward for a test.
Dr Alex Osborne, policy manager at Alzheimer’s Society, said: “An early, accurate diagnosis is vital for unlocking care, support, and treatment.
“A third of people living with dementia in England don’t have a diagnosis, meaning they’re missing out on the benefits it can bring. There’s also significant regional variation in diagnosis rates. This needs to change.”
He added: “We’re close to meeting the existing target of a 66.7 per cent diagnosis rate – so now we’d like to see bold, ambitious but achievable new targets set for the future to ensure everyone gets the diagnosis they need.”
Experts believe that new tests could help to speed up diagnosis by predicting the onset of the disease before symptoms appear.
Last month scientists at Queen Mary University in London developed a test that can predict dementia up to nine years before diagnosis with 80 per cent accuracy.
A trial found that the test was more accurate than memory tests or measurements of brain shrinkage, two commonly used methods for diagnosing dementia.
New treatments are also being developed, such as lecanemab, that scientists hope will slow disease progression in people with early Alzheimer’s disease.