«Faculty for People with Intellectual Disabilities Dementia and People with Intellectual Disabilities Guidance on the assessment, diagnosis, ...»
Case reports, cross-sectional and longitudinal studies have all confirmed an increase in the 10 Dementia and People with Intellectual Disabilities prevalence rates of clinically diagnosed dementia with increasing age that starts when people with Down’s syndrome are in their 30s and steadily increases in prevalence into the 60s. These rates are not as great as neuropathological studies initially suggested would be the case and, whilst the precise rates differ between studies, it is clear that not all people with Down’s syndrome present with the pattern of memory loss and functional decline characteristic of dementia in later life. Nevertheless, using cumulative incidence rates it has been calculated that nearly 70 per cent of older adults with Down’s syndrome are likely to develop dementia symptoms should they all live to age 70 (Zigman et al., 2002).
Recent analysis by the ADSID collaboration (Strydom 2014) using data from assessment clinics across England (N = 338 cases with Down’s syndrome and dementia) established that the majority of individuals with Down’s syndrome who are diagnosed with dementia presented in their 50’s (interquartile range 50.9 – 59.3 years), with a mean age at diagnosis of approximately 55 years (SD 6.5). A quarter was diagnosed before the age of 50, and a quarter after age 60. Survival varied considerably, but did not appear to be much shorter than the general population with a mean survival time of 4 years following diagnosis.
Figure 1: Comparison of dementia prevalence rates by age
Figure 1 summarises the age-related prevalence rates of dementia in people with Down’s syndrome, those with intellectual disabilities without Down’s syndrome, and in the general population. The exact rates have to be considered with caution but the trend represented in this figure is now increasingly accepted. The early presentation and course of dementia is now well established for people with Down’s syndrome. For those with intellectual disabilities but without Down’s syndrome, age-related prevalence rates are brought forward to a small degree compared to the general population but not to the same extent as for people with Down’s syndrome. This latter group would appear to have a uniquely early risk for developing dementia, almost invariably of the Alzheimer’s type. For the former group the full range of causes of dementia is observed.
Amyloid is the protein that, in an insoluble form, forms the neural plaques characteristic of Alzheimer’s disease. The gene coding for the Amyloid Precursor Protein (APP) is Guidance on their Assessment, Diagnosis, Interventions and Support 11 located on chromosome 21, and this is likely to account for the increase in risk of Alzheimer’s disease in people with Down’s syndrome. Children with Down’s syndrome have been found at post mortem to have evidence of diffuse cerebral amyloid deposition and in adult life plaques and tangles characteristic of Alzheimer’s disease are found. The assumption therefore is that this slow deposition of amyloid in the brain leads to a cascade of adverse neural events over time and ultimately to the full pathology of Alzheimer’s disease. Further evidence implicating the extra copy of the APP gene in Alzheimer’s disease in Down’s syndrome was reported in a rare case of partial trisomy 21 without triplication of the APP gene. Neuropathological changes associated with Alzheimer’s disease did not occur; neither did clinical dementia develop despite the advanced age of the individual (Prasher et al., 1998). However, whilst the brain pathology characteristic of Alzheimer’s disease would seem to be near universal in later life, it is clear that not all of the older people with Down’s syndrome with full trisomy 21 develop the clinical features of dementia. The reason for this remains unclear.
Key points People with intellectual disabilities have a higher risk of developing dementia I compared to the general population, with a significantly increased risk for people with Down’s syndrome and at a much earlier age.
Life expectancy of people with Down’s syndrome has increased significantly and the I number of older people with Down’s syndrome has been increasing.
The incidence and prevalence of Down’s syndrome is relatively stable.
I 12 Dementia and People with Intellectual Disabilities Section 3 – Baseline assessment and monitoring
3.1 Reactive, baseline assessment and prospective monitoring A core feature of dementia is a decline from a baseline level of the person’s functioning.
Establishing pre-morbid skills, abilities and personality can be challenging in the intellectual disability population due to variance in cognitive functioning and abilities, frequent poor record keeping from childhood and the possible lack of consistent involvement of family or staff throughout the person’s lifespan.
Signs of early dementia can be subtle and require careful observation to identify concerns in a timely way. Families and staff carers can often be so close to the person that they become less able to recognise minor changes in functioning through adapting to the person’s needs. Similarly, for some people there is an absence of people who can comprehensively describe and evidence the person’s baseline of functioning, the role of baseline cognitive assessment becomes apparent.
Services need to consider what type of service they offer to people with intellectual
disabilities who may develop dementia. Services will need to do the following:
Provide reactive screening. This relates to the assessment of functioning and the I development of a formulation exploring the reasons for observed deterioration in any adult with intellectual disabilities after concerns have been raised. Information relating to dementia care pathways and the roles of the multidisciplinary team can be found in Section 6.
Establish a baseline for every adult with Down’s syndrome whilst they are healthy – I ideally at age 30.
Services may also consider undertaking prospective screening for dementia for adults with Down’s syndrome conducted at intervals from the age of 30 onwards.
Good practice guidance from the Foundation for People with Learning Disabilities (Turk et al., 2001) recommended that every service for people with intellectual disabilities should set up a register of adults with Down’s syndrome, conduct a baseline assessment of cognitive and adaptive functioning by the age of 30 years (being mindful of likely continued brain development throughout the second decade of life). Despite this, the availability of assessment and treatment across the UK remains inequitable. Most areas now offer reactive assessment for those with signs of deterioration, and a number of services now offer baselines and prospective screening to adults with Down’s syndrome such as that described by Hobson et al., 2012, Cairns et al., 2010; Jervis & Prinsloo, 2007; McBrien et al., 2005.
Tools used for dementia assessment are described in section 6.
3.2 Reactive monitoring Reactive monitoring is the most common service provided by intellectual disabilities services. However, the reliability and efficiency of reactive screening can be greatly enhanced if a baseline assessment is available, as data can be compared in a timely way.
Guidance on their Assessment, Diagnosis, Interventions and Support 13 Reactive assessment means conducting a thorough assessment of cognitive and social functioning after concerns about deterioration have been raised. This relies on carers noticing relevant signs of change and making a referral to the GP or intellectual disability service. This does not always occur in a timely manner. Due to high turnover of staff in many intellectual disabilities residential settings, staff may not be aware of changes in a person’s presentation and diagnostic overshadowing can occur. To enhance this brief dementia checklists can be used by residential staff or at annual reviews (e.g. Whitwham et al., 2011), and staff awareness training can be provided for services supporting people with intellectual disabilities.
3.3 The importance of baseline assessment There is no definitive ‘test’ for dementia. Its presence is a matter of eliciting a clinical history suggesting dementia and establishing evidence of change in function from a known baseline and excluding other diagnoses that may mimic dementia. In the mainstream population, it is more straightforward to gauge pre-morbid functioning from self-report or employment history than it is in the population of people with intellectual disabilities where self-report is limited and few paid carers are in possession of a full history.
Unless a baseline is established when the person is healthy, it is difficult to know whether there has been a deterioration later in life. By the time an individual is referred with concerns, considerable deterioration may have already occurred and an accurate account of pre-morbid functioning may be difficult to construct. Longitudinal data is then needed to establish decline from a baseline as it is not possible to compare results of an assessment with an ‘average’ result for the person with Down’s syndrome, intellectual disabilities or general population.
Whilst it may be possible to establish a diagnosis of dementia from a one-off assessment when there is good historic data from which to compare, or the clinical picture is extremely clear, there is a risk of false negative or positive diagnoses.
Prompt diagnosis ensures that attention can be paid in a timely way to necessary changes to a care package, medication, preparing family carers and support staff for the inevitable changes and challenges that dementia will bring.
When should baseline assessment occur?
There is currently no clear evidence base as to the best age at which this should occur;
however, setting a baseline when the client is healthy and functioning at their best will clearly be most helpful at re-screen should concerns arise. It has been suggested that an assessment by the age of 30 years would be helpful (Turk et al., 2001; McBrien, 2009).
Ongoing neurodevelopment in late adolescence and early adulthood should be considered so as not to set baselines at too early an age when the brain is still developing.
Carr (2000) demonstrated stability in intellectual ability and daily living skills for her cohort of people with Down’s syndrome during the age period 21–30 years. This suggests that a baseline conducted by the age of 30 would helpfully capture people prior to any cognitive decline.
Ideally, a baseline assessment at age 30 years would capture an individual’s functioning once the brain is thought to be relatively fully developed, and before the potential onset of 14 Dementia and People with Intellectual Disabilities dementia. A copy of the baseline assessment should be given to the person and their carers to keep in the person’s health action plan for future reference.
Functional limitations of electronic health record systems may require the development of additional databases to capture relevant clinical information about clients with Down’s syndrome, or people on dementia care pathways. It is important to be aware of relevant data protection issues and organisational protocols (such as registering your database with the Trust’s information governance department) and be mindful of the potential need to gain consent/assent from service users and/or their carers to have personal information recorded in such a way.
Some services seek simultaneous consent for inclusion on dementia databases alongside permissions to contact clients regarding possible research projects that may be of interest in the future.
3.4 Prospective monitoring Prospective monitoring entails checking for early signs of dementia by repeating the baseline assessment at regular intervals. This necessitates, as do baseline assessments, having a register of all adults with Down’s syndrome and additionally a method of recalling people for a re-assessment. Jethwa and Cassidy (2010) and O’Caoimh et al. (2013) suggest an accurate and extensive record of baseline skills levels in people with intellectual disabilities is crucial and regular comparison with baseline is key to early diagnosis.
The frequency of prospective monitoring for dementia should be matched to the rising risk with age. For example, the baseline assessment should take place at 30 years; then every two years for those in their 40s; and annually for those aged 50 and over. Assessment is non-invasive and is usually enjoyable for the participant (see Section 6).
Additional benefits of regular assessment One argument in favour of prospective screening concerns the known health risks for all people with Down’s syndrome. Many treatable illnesses can produce symptoms of cognitive decline independent of dementia. The evidence is that all too often, such disorders remain undetected in intellectual disabilities populations (Watchman, 2014). This applies particularly to people with Down’s syndrome who are prone to certain health problems (Coppus, 2014). Many carers and indeed some GPs are not aware, for example, of the need for routine thyroid function tests for adults with Down’s syndrome. There are useful factsheets, available free of charge on the internet from the Down’s Syndrome Association, that can be used to raise awareness of this issue.
A review of six months of routine prospective screens carried out in one intellectual disability service showed that of 33 prospective assessments of apparently healthy adults with Down’s syndrome, 12 (36 per cent) revealed concerns that had not previously been identified by carers. These included dementia-like symptoms (memory and behavioural change), physical or mental health concerns that could be immediately treated, and action required by social services, including one requiring the instigation of the safeguarding protocol (Major & McBrien, 2011). It is hoped that improved access to regular heath screening (e.g. annual GP health checks) will help to minimise the prevalence of undetected physical and mental health concerns.
Guidance on their Assessment, Diagnosis, Interventions and Support 15 Prospective assessments – should we or shouldn’t we?