Dementia and the Mental Capacity Act 2005

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Mental Capacity and dementia

When a person has mental capacity, it means they are able to make a specific decision at a specific time. People who can’t do this are said to ‘lack capacity’ to make that decision. 

This might be due to having an injury, a learning disability, a mental illness or a condition that affects the brain – such as dementia. 

To have mental capacity to make a specific decision, a person must be able to: 

• Understand the information that is relevant to the decision they want to make.
• Keep the information in their mind long enough to make the decision.
• Weigh up the information that is available to make the decision.
• Communicate their decision in any way. This can include talking, sign language or simple movements, such as blinking or squeezing a hand. 

As their condition progresses, a person with dementia may become unable to make some decisions. When this happens, they are considered to lack the mental capacity to make the decision at that time. With dementia, mental capacity can change over time. 

Mental capacity can also change in both the short term and the long term. For example, there might be days or even times of the day when the person can think more clearly. This means they may have capacity to make a decision at some times but lack capacity at other times. 

A person may also have the capacity to make some decisions but not others. For example, a person may be able to decide that they want to go on holiday but not be able to make choices about accommodation options. This is because some decisions involve having to take in more information. This can be harder for the person to process or understand. 

Some decisions, such as whether to move into a care home, involve many factors to weigh up. This may also be harder for the person to consider. You should not assume that a person can’t make simple decisions, such as what to wear, just because they can’t make difficult financial or medical ones.

What is the Mental Capacity Act?

The Mental Capacity Act is the law in England and Wales that protects and supports people who lack capacity to make a decision. It also outlines who can and should make decisions for them. 

The Mental Capacity Act covers decision-making about a person’s property, financial affairs, and health and social care. It also covers everyday decision-making, such as what a person wears, what they eat and their personal care.

It does not cover decisions such as voting, making a will, marriage or divorce. For advice on these decisions, talk to a relevant professional or visit gov.uk. 

The Act can help people with dementia, their carers and professionals to make specific decisions and to plan for the future.

The principles of the Mental Capacity Act

The Mental Capacity Act is based on five key principles or rules, which are mentioned throughout this factsheet. These are: 

1. A person has the right to make decisions for themselves. You must assume that someone is able to make their own decisions, unless it is shown that they can’t do this.  
2. A person should not be treated as being unable to make a decision unless they have been given all reasonable help and support to make and communicate their own decision.
3. A person should not be treated as being unable to make a decision just because other people think they have made a bad decision.
4. If a person lacks capacity, any decisions that other people make for them must be in the person’s best interests. The Act includes a checklist that people must work through when they are deciding what is in the ‘best interests’ of someone who lacks capacity.
5. If a person lacks capacity, the people making the decision for them must consider the option that is the least restrictive to the person’s rights and freedoms.