It's thought as many as 50,000 people may be living with dementia in the East - but haven't been diagnosed.
The statistics obtained by the Alzheimer's Society found doctors in some areas are spotting only a third of cases.
It means patients are missing out on the vital support they need.
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Showers dying out during this evening to leave a dry night with some long clear spells leading to a frost by morning. Lows -1 deg C
A protest march has been held in Huntingdon over plans to merge two local hospitals to save money.
A protest march has taken place in Huntingdon over plans which could see Hinchingbrooke Hospital merge with Peterborough City Hospital