Who will be affected by the Mental Capacity Act?

Some people will be affected because their capacity to make particular decisions is an issue. But anyone could choose to use parts of the Mental Capacity Act to plan for the future when they may lack the capacity to make particular decisions for themselves.

It is difficult to estimate the exact number of people who lack the capacity to make decisions, and often people are able to make some decisions but not others. Government estimates for England and Wales range from one to two million adults where there may be issues about capacity and this approximately includes:

  • 840,000 people with dementia (although not everyone with dementia lacks capacity)
  • 145,000 people with a severe learning disability
  • 1.2 million people with mild to moderate learning disability (many do not lack capacity)
  • 120,000 people with a severe brain injury

Note that:

  • People with a mental illness do not necessarily lack capacity to make specific decisions. However, people with a severe mental illness may experience a temporary loss of capacity to make decisions about their care and treatment.
  • People who are under the influence of drugs and alcohol may also experience temporary loss of capacity and in some urgent situations (such as when in accident and emergency situations) the Mental Capacity Act may be used with this group.
  • In general, the Mental Capacity Act applies to people aged 16 years and older but there are some exceptions.

In the context of the Mental Capacity Act, mental capacity is the ability to make a decision. A person’s ability to make a decision can be affected by a range of factors such as a stroke, dementia, a learning disability or mental illness. A person’s capacity may vary over time or according to the type of decisions to be made. Physical conditions, such as intimidating or unfamiliar environment, can also affect capacity. Trauma, bereavement and health problems can also affect a person’s capacity.