4. Symptoms of dementia in people with a learning disability
The symptoms of dementia in people with Down's syndrome are broadly similar to those seen in the general population, although there are some differences. Changes in behaviour and personality (eg becoming more stubborn, irritable or withdrawn) or loss of daily living abilities are common. Memory loss, the most common early symptom of Alzheimer's disease among older people generally, is seen less often as an early symptom in people with Down's syndrome. This may be because most people with Down's syndrome will already have poor short-term memory.
People with Down's syndrome are more prone to epilepsy (fits) than others. However, if a person with Down's syndrome starts to develop epilepsy later in life, it is almost always a sign of dementia and should be investigated thoroughly. Up to three-quarters of people with Down's syndrome and dementia develop fits. More severe seizures are linked to a more rapid decline in health.
The middle and later stages of dementia in people with Down's syndrome are similar to these stages in the general population. However, there is some evidence that dementia in people with Down's syndrome progresses more rapidly. They may have earlier loss of basic skills such as walking, becoming incontinent and having swallowing difficulties.
Other learning disabilities
Dementia in people with a learning disability other than Down's syndrome is less well studied and symptoms can vary widely. For those with mild learning disabilities, dementia seems to appear and progress similarly to dementia in the general population. For those with more severe learning disabilities, the initial symptoms of dementia are often less typical, possibly involving changes in personality or behaviour. This can make diagnosing dementia harder.
How can you tell if someone might be developing dementia?
A person with a learning disability will already have some differences in their thinking, reasoning, language or behaviour, and their ability to manage daily living. It is a change or deterioration in these - rather than a single assessment - that may suggest dementia. This means carers, friends and family play an important part in helping to identify early signs of dementia, such as changes in behaviour or personality and loss of day-to-day abilities. They should raise any concerns promptly with their GP or learning disability team.
It is recommended that every adult with Down's syndrome is assessed by the time they are 30 to provide a record or 'baseline' with which future assessments can be compared.
As well as this baseline assessment, an adult with Down's syndrome should routinely be offered an annual health check with their GP. This health check will include:
- a physical health check of the person's weight, heart rate and blood pressure, as well as blood and urine tests
- eyesight and hearing tests
- a review of any medicines the person is taking
- an assessment of the person's communication skills
- an assessment of the person's behaviour, including their lifestyle and mental health (such as possible depression)
- an assessment for possible dementia.
The health check should lead to referral to a specialist, if needed, and an agreed health action plan that outlines what the person can do to stay healthy.
The process of assessment and diagnosis for possible dementia in someone with a learning disability other than Down's syndrome is similar to that for the general population.
However, a learning disability does make the diagnosis more complicated. It is important not to assume that a person with a learning disability has dementia simply because they fall into a high-risk group or because they are getting older. Equally, it is important that symptoms of dementia are not missed because they are mistakenly seen as part of the learning disability.
Assessment for someone with Down's syndrome is best done by a multidisciplinary team that includes a GP, psychiatrist, community learning disability nurse, occupational therapist and clinical psychologist. Each, with the exception of the GP, should be a specialist in learning disabilities. The learning disability service may work closely with the nearest memory clinic (where people are routinely assessed for suspected dementia) for advice on diagnosis or management.
The process will include:
A detailed personal history - This is vital to establish the details of any changes that have taken place. It will usually include a discussion with the main carer and any care service staff who understand the person and how they communicate. This history should include any significant changes in the person's life, such as moving home, a favourite care worker leaving or a recent bereavement.
A full health assessment - It is important to exclude any physical causes that could explain changes in the person or their behaviour. There are a number of conditions that have similar symptoms to dementia but are treatable, for example underactive thyroid, which is more common in people with Down's syndrome. Any medication that the person is taking will be reviewed. Problems with vision and hearing are more common in people with learning disabilities so these should also be looked at.
Psychological and mental state assessment - It is important to rule out mental ill health, including depression, as a cause of memory loss. Standard tests that measure mental ability (such as the Mini Mental State Examination) are not appropriate for people with learning disabilities, as they already have some mental impairment and may not have the language or memory skills that the tests require. A range of assessment tools have now been developed specifically for people with Down's syndrome or other learning disabilities. Assessment with one of these tools will be done by a clinical psychologist or other specialist with experience of learning disabilities.
Special investigations - It can be difficult to interpret a brain scan from someone with a learning disability, and the person may find having a scan distressing. However, a brain scan may be useful in excluding other conditions (eg tumour, bleed) when an assessment for suspected dementia has not been conclusive.
Even with a thorough assessment, it will not always be possible to reach a clear diagnosis. This may mean waiting, watching carefully to see how the person gets on, and then repeating the assessment several months later.