A large number of patients are not getting the follow-up care they are entitled to after a dementia diagnosis, a charity has said.
New analysis by charity Age UK found that thousands of people with the condition do not have a current care plan - a document which sets out what care the person is having and contingency plans for the future.
The charity said that such plans are the "gateway to follow-up support from the NHS" and ensure joined-up support from other bodies such as social care services.
Patients should have a regularly reviewed plan which reflects the changes in their condition and NHS England has said that there is an "urgent need" to ensure every person who has dementia has an individual care plan, which is reviewed annually.
But following analysis of data from 7,185 GP practices in England, the charity found that of 458,461 people who had a recorded diagnosis of dementia in November 2017, only 282,573 had a new care plan or at least one care plan review on record in the last year.
In 2015, there were 850,000 people with dementia in the UK, by 2025, the number is expected to hit one million.
Caroline Abrahams, Age UK's charity director, said: "Our analysis suggests that many people with dementia are losing out on the NHS follow-up support they need and are supposed always to be offered, once they have received their diagnosis.
"As a result they and their loved ones are missing precious opportunities to get help with living as well as possible with the disease.
"The absence of a care plan also means that people with dementia are not being sign-posted to services that really could improve their physical and mental health, and sense of wellbeing."
The charity's latest report highlights a number of "evidenced and cost effective" projects which make a difference for dementia patients, which it says could be replicated by care bodies, including NHS trusts.
These include arts and crafts activities, helping people to reminisce through dance and counselling sessions.
An NHS England spokesman said: "The NHS has worked hard to dramatically increase the number of people receiving a formal dementia diagnosis so they can access the right care and support.
"A care plan is only part of high-quality dementia support, which is why we have introduced new measures to help local NHS groups and GPs plan for ongoing care and will continue to help deliver further improvements."