The current estimate is that over 700,000 people in the UK have dementia, most of them with Alzheimer's disease, that gradual death of the brain cells which changes behaviour, personality and the ability to make decisions. By 2021 the number is expected to increase to 840,000.

"Mind Your Head" - the Alzheimer's Society's publication for Alzheimer's Awareness Week back in July - listed some "top tips" for reducing the risk of developing dementia, such as not smoking, reducing intakes of salt and saturated fat, taking regular exercise (while also taking care to avoid head injuries), having an active social life, eating fruit and veg, drinking alcohol in moderation, eating oily fish once a week and keeping a check on blood pressure and cholesterol levels.

However its authors cautioned "anyone can develop dementia, including people who are following a low risk lifestyle".While age is the greatest risk factor, early dementia is also an increasing concern. For instance, Brighton and Hove's Towner Club provides day activities for people below retirement age. There are about 18,500 people under 65 with dementia in the UK.

There is no cure although a range of treatments, including drugs, can delay its development or enhance the quality of life for dementia sufferers, enabling people to continue a little longer with everyday tasks like washing and dressing, retaining a degree of independence.

The effectiveness of NICE guidelines on the availability of drugs can still depend on early diagnosis by a GP and referral to a consultant for the initial prescription - and on the policies and budgets of individual Health Authorities and Primary Care Trusts.

The very fact that dementia respects no one makes it all the more important for our society to do everything possible to show respect for people with dementia - and enable them to retain their self-respect.

Other countries - Australia and Canada and, since 2000, Scotland - already have legislation to protect citizens who no longer have the capacity to make decisions for themselves or whose diagnosis means they will eventually be in that condition. But in England and Wales the law is fragmented and confused.

That's why the government's draft Mental Incapacity Bill - published in June this year - was welcomed by the Alzheimer's Society and the other charities in the Making Decisions Alliance.

Of course the bill has implications not only for people in England and Wales with dementia, but also for those with forms of autism, profound learning disabilities, severe mental health problems and people who have suffered severe head injuries.

Its aim, according to the minister in charge Lord Filkin, is "to introduce a comprehensive decision-making framework for all people who may lack capacity"a clear, simple, informal system that will ensure people can maintain a maximum level of autonomy".

The draft bill provides that, with help when necessary, people continue to be involved in decision-making for as long as possible, including decisions about future treatment and care. It will set out a new single definition and test for incapacity, the concept of "best interest" with a statutory "best interest" checklist when another person makes the decisions, Lasting Powers of Attorney to extend existing decision-making powers to a chosen person and a new single court, supported by a Public Guardian, for resolving disputes.

Clearly the proposals also have vital implications for the six million people who are families and carers and who - usually willingly but sometimes through the absence of other support - so often take on the day to day tasks necessary to ensure their relative or friend retains dignity and a degree of independence.

Since 1997 the government has taken a number of steps which recognise and support the carer's role with, for the first time, a National Carer's Strategy, improvements to the Invalid Care Allowance, the carer's right to an assessment and the Carer's Grant. The Second state pension recognises the needs of people who left work early to take on caring responsibilities and who might miss out on pension entitlements.

But, as with treatment for patients, there can be inequalities in access to that support. Even in an area like mine with a long-established and active Alzheimer's Society Branch and a permanent Carer's Centre it's still not unusual to find - often elderly - wives, husbands, partners and friends cut off from neighbours, caring for someone and with no or little awareness of the help either statutory or in the form of voluntary respite which is available.

Isolation and a lack of information are still the main problems for carers. Add to this the current baffling state of the law on incapacity which can present a further nightmare for the carer often at an extremely distressing time.

The bill aims to involve family and friends in decision-making with a clear legal "general authority to act". The Lasting Power of Attorney could involve the person already diagnosed in deciding who eventually has decision-making rights.

Not only family carers but healthcare professionals as well should benefit from a clear legal framework about "best interest" in the provision of treatment.

Public consultation on the bill finished in August and the bill will now go to a joint committee of both Houses of Parliament. Both processes could make the bill even more responsive to people's real needs and experience.

Although lobbying might be needed to secure a place in the legislative timetable, the government should need little persuasion to make space for a measure which could mean so much for the self-respect, as sufferers or carers, of any one of us.

David Lepper is the Labour MP for Brighton Pavilion, a member of the Alzheimer's Society and a trustee of ARDIS, a Brighton and Hove based charity working to support dementia patients and their carers. In 1993 as the then Mayor of Brighton he initiated Action of Alzheimer's a year-long project to raise funds for Alzheimer's organisations locally and awareness about the condition