«Faculty for People with Intellectual Disabilities Dementia and People with Intellectual Disabilities Guidance on the assessment, diagnosis, ...»
The evidence does not currently indicate a need for prospective screening for people with intellectual disabilities without Down’s syndrome. Screening for people with Down’s syndrome needs to be justified in terms of likely gain, the demands placed on the service, and there needs to be consideration of the issue of informed consent. Some services may decide against it for reasons of intrusion, commissioning intentions and/or resource limitations. Apparent changes in scores on cognitive assessments do not in themselves indicate dementia but do require further investigation.
3.5 Ongoing Monitoring Regardless of whether a service offers prospective monitoring, it is important that a programme of regular monitoring and reassessment is established once the person is suspected of having dementia. This will enable the progression of the disease to be described, suitable medical, psychosocial and environmental interventions to be put in place, and the quality outcome for the person to be measured. See Sections 6, 12 and 18.
Key points It is recommended to assess every adult with Down’s syndrome by the age of 30 to I establish a baseline against which to compare future suspected changes in functioning.
It is worth considering screening all adults with Down’s syndrome over 40 regularly I because of the increased risk of dementia and the prevalence of undetected but treatable illnesses. This should link to the person’s health action plan.
Once the person has been suspected of having dementia, a programme of regular I monitoring and reassessment needs to be established.
16 Dementia and People with Intellectual Disabilities Section 4 – Possible reasons for apparent decline in functioning in adults with intellectual disability Changes in functional ability with or without behaviour change are often the initial presentation of dementia in adults with intellectual disabilities. It is important to remember, however, that some changes may be part of the normal ageing process. There are a number of other reasons an individual with intellectual disabilities may show a cognitive decline. The list below, whilst not exhaustive, describes the most common reasons for change in ability. It is important to recognise that two or more conditions can co-exist.
1. Dementia: The typical presentation of dementia is one of gradual loss of skills along with change in personality and cognitive decline. Dementia is a diagnosis of exclusion therefore, it is important to consider other conditions that may cause loss of skills and cognitive decline, especially as many of these are treatable.
2. Physical problems include such conditions as hypothyroidism, anaemia, uncontrolled epilepsy and chronic infections. Electrolyte abnormalities, hypo- or hyper-glycaemia, nutritional deficiencies particularly vitamin B12 or folate could also cause functional decline in adults with intellectual disabilities. A thorough physical examination and relevant clinical tests are required at the time of initial assessment. These may need to be repeated from time to time as necessary.
3. Sensory impairments: People with intellectual disabilities in general and those with Down’s syndrome in their middle/old age specifically are likely to develop hearing and visual impairments. Visual impairment could be due to development of cataract or conditions such as keratoconus in individuals with Down’s syndrome. Some 60–80 per cent of people with Down’s syndrome will have hearing problems at some point in their lives. Conductive hearing deficit caused by earwax and the narrow acoustic canal is frequently seen in people with Down’s syndrome.
4. Mental health problems: The most common differential diagnosis is depressive illness (McBrien, 2003) but other conditions such as the exacerbation of an existing psychotic disorder can mimic the presentation of dementia. Severe anxiety can also cause an apparent decline in functioning.
5. Sleep problems: Obstructive sleep apnoea or other sleep disorders can cause day time drowsiness, mental slowing as well as confusion, and are particularly common in people with Down’s syndrome. Day time drowsiness and slowing could be interpreted as dementia if the sleep problem is not identified.
6. Iatrogenic (medication related) causes: Medications with anticholinergic side effects can cause cognitive impairments in elderly people and people with intellectual disabilities. Use of high dose psychotropic/anti-epileptic medications and multiple medications can contribute to cognitive impairment as well. Some of the common medications that could cause a dementia-like presentation are listed in Table 1.
Guidance on their Assessment, Diagnosis, Interventions and Support 17 Table 1: Some common medications that could cause a dementia-like presentation (Diagnosis and treatment guideline, Mayo Foundation for Medical Education and Research, (Moran et al., 2013))
7. Impact of life events: People with intellectual disabilities in their middle age can face a number of life events such as loss of a parent or long-term carer, moving away from home or loss of day activities. In some individuals, the impact of life events may lead to a regressive state with apparent loss of skills. Changes in routine such as new structure to day opportunities or changes in support staff can cause profound reactions in an individual with intellectual disabilities leading to functional decline and a dementia- like presentation.
8. Abuse: Current or recent physical, emotional or sexual abuse in people with intellectual disabilities may result in loss of skills and regression and the development or exacerbation of behaviour problems that might superficially mimic dementia.
9. Impact of poor environment: An unsuitable environment associated with a lack of stimulation, isolation and lack of social opportunities for positive interaction can lead to loss of skills. In the event that this is also associated with changes in support structure, where people do not know the individual well, these changes may be attributed to dementia.
10. Acute organic brain syndrome: This may co-exist with dementia or be part of the differential diagnosis. Someone with uncontrolled epilepsy, for example, could present with confusional state that may mimic dementia. People with dementia may deteriorate rapidly and develop an acute confusional state when they have an acute physical health problem such as a urinary tract or respiratory infection.
18 Dementia and People with Intellectual Disabilities Key points The common differential diagnoses for individuals with Down’s syndrome I presenting with loss of skills are depressive illness, sensory impairments (hearing or visual), hypothyroidism, obstructive sleep apnoea and dementia.
Sometimes conditions can co-exist.
I Do not forget about the following causes of apparent functional decline as these are I
– iatrogenic causes of cognitive impairment particularly when the individual is taking multiple medications;
– impact of the environment particularly in relation to occupational deprivation and under stimulation; and – impact of abuse on the individuals with ID.
Guidance on their Assessment, Diagnosis, Interventions and Support 19 Section 5 – Clinical presentation of dementia
5.1 Criteria for dementia Within the general population, diagnostic criteria have been developed in order to improve the accuracy of the clinical diagnosis of dementia. These include the ICD-10 and DSM–5 criteria. These are summarised below.
ICD-10 (WHO, 1992) criteria (summary)
1. Evidence of decline in memory, most evident in the learning of new information. The impairment applies to both verbal and non-verbal material and is sufficient to interfere with everyday function.
2. A decline in other cognitive abilities and daily living skills, characterised by deterioration in judgment and thinking such as planning and organising, and in the general processing of information, to a degree leading to impaired functioning in
daily living. These include:
• language comprehension and expression;
• executive function;
• usual daytime activities; and
• use of household utensils and equipment.
3. Absence of clouding of consciousness/delirium.
4. Decline in emotional control, motivation or social behaviour in at least one of the
• emotional lability;
• apathy; and
• coarsening of social behaviour.
5. The duration in changes in memory must be longer than six months.
DSM–5 criteria (American Psychiatric Association, 2013) The DSM–5 has renamed dementia as ‘neurocognitive disorders’ and recognises both minor and major neurocognitive disorder.
Major neurocognitive disorder (dementia) is defined as:
1. Evidence of a significant decline from a previous level of performance in one or more cognitive domain (such as attention, executive function, learning and memory,
perceptual motor or social cognition) which is based on:
a. report of significant decline in cognitive function by the individual themselves, a knowledgeable informant, or a clinician;
b. a substantial impairment in cognitive performance is documented by clinical assessment, preferably standardised neuropsychological testing.
20 Dementia and People with Intellectual Disabilities
2. The cognitive deficits interfere with independence in everyday activities (which is defined as at a minimum requiring assistance with complex instrumental activities of daily living such as paying bills).
3. The deficits do not occur exclusively in the context of a delirium.
4. The deficits are not better explained by another mental disorder (e.g. major depressive disorder or schizophrenia).
Subtypes should be specified (e.g. Alzheimer’s disease).
It is not yet known how the DSM–5 criteria for dementia will perform in this population, but it in the general population, DSM–IV criteria have been found to be more inclusive compared to ICD10 criteria. This was also the case in people with intellectual disabilities (Strydom et al., 2007). ICD10 and DSM–IV dementia criteria both showed substantial reliability and satisfactory validity in older adults with intellectual disabilities without Down’s syndrome, although caution is advised when using these criteria in people with more severe intellectual disabilities and/or co-morbid sensory disabilities and predictive validity was slightly worse than in the general population (Strydom et al., 2013). ICD10 criteria were more likely to accord with clinician diagnoses than DSM–IV criteria in people with Down’s syndrome who have been diagnosed clinically with dementia, possibly due to the inclusion of behavioural symptoms in the ICD10. However, both sets of criteria underdiagnosed dementia compared to clinician judgement, suggesting that experienced clinicians used their clinical knowledge of the slightly atypical dementia presentation in Down’s syndrome to diagnose the disorder at an earlier stage than would be possible if they applied the diagnostic criteria (Sheehan et al., 2014).
5.2 Course of the disease Dementia is at present untreatable and has a progressive course. In the general population each of the different types of dementia has characteristic clinical features. The presentation and course of dementia has been studied in people with Down’s syndrome but less so in those with intellectual disabilities. However, some general observations can be made.
People with Down’s syndrome The most common form of dementia in people with Down’s syndrome is Alzheimer’s disease. It is known that the brain pathology of Alzheimer’s disease is almost universally found in later life in people with Down’s syndrome. Vascular disease, and therefore the risk of dementia of a vascular origin, is rare.
Dementia in people with Down’s syndrome may present atypically with changes in behaviour and/or personality that can precede the full clinical picture of dementia by some years.
A number of studies have reported that behavioural changes, rather than functional memory decline, are the early signs of developing dementia and Ball et al. (2006) have proposed that this may be explained by limited reserve capacity of the frontal lobes of people with Down’s syndrome. Longitudinal neuropsychological studies have also found that some discrete cognitive abilities, as measured using established neuropsychological tests, show evidence of increasing impairment over time starting in the early and preGuidance on their Assessment, Diagnosis, Interventions and Support 21 clinical stages of dementia. Thus memory and orientation are affected early, with praxis, language and visuo-spatial skills becoming impaired later in the progression of the disorder (see Ball et al., 2006 for review).
The behavioural problems associated with dementia may take the form of behavioral excesses such as irritability, aggression or self-injury and then behavioral deficits which would include slowness, apathy loss of interest and lessened social engagement (Oliver et al., 2011).
The middle and later course of Alzheimer’s disease in people with Down’s syndrome and for those with other causes for their intellectual disabilities are comparable in characteristics to those experienced by people in a similar stage of dementia but without pre-existing intellectual disabilities, though in individuals with Down’s syndrome neurological symptoms are common, and include the onset of seizures for the first time in that person’s life. Late stage symptoms are characterised by the individual’s lack of response to the environment, loss of mobility, loss of communication skills, incontinence, seizures and may include Parkinsonian features (Visser et al., 1997; Strydom et al., 2010).
The progression of dementia in people with Down’s syndrome with dementia has been reported to be more rapid than in the general population. However, it may be that diagnosis occurs later in this population (Bush & Beail, 2004).
People with intellectual disabilities are at high risk for additional co-morbid illness that might impact on both the way that dementia presents and its progression over time.