Section of Developmental Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge CB2 2AH
See editorial pp.
1011, this issue.
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ABSTRACT |
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Aims To identify some key biological, psychological and social issues relevant to how ageing might particularly effect people with learning disabilities.
Method This selected review considers the extent to which there are similarities and differences relative to people without learning disabilities.
Results There is a convergence, in later life, between people with a learning disability and those without, owing to the reduced life expectancy of people with more severe disabilities. People with Down's syndrome have particular risks of age-related problems relatively early in life.
Conclusions The improved life expectancy of people with learning disabilities is well established. There is a lack of a concerted response to ensure that the best possible health and social care is provided for people with learning disabilities in later life.
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INTRODUCTION |
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AGEING: AN EPIDEMIOLOGICAL PERSPECTIVE |
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As life expectancy has improved and, in the developed world, birth rate has
fallen, the proportion of older people has increased. One striking prediction
is that the proportion of people over the age of 85 will increase from 6% of
those aged over 60 to 11%. In early old age there is a reasonably predictable
pattern of cognitive change, but in this older elderly group the major
debilitating disorders, such as Alzheimer's disease, become particularly
prevalent and lead to the potential for a significant increase in disability
among this group. Even in the developed world, there are differences between
countries and between socio-economic classes in terms of life expectancy. For
example, those living in southern Europe have among the best life expectancy.
This pattern changes with migration and changes in lifestyle. Epidemiological
studies suggest that, for example, diet and drinking habits have both positive
and negative effects. From a different perspective there is also evidence that
allelic variations at specific genetic loci (e.g. apolipoprotein )
affect life expectancy and the propensity to age-related illnesses such as
Alzheimer's disease (Rubinsztein,
1995). So, as life expectancy has improved for people with
learning disabilities, the above influences, and most importantly the presence
or absence of age-related disabilities, become increasingly relevant.
Questions can appropriately be asked about the influence on the health and
well-being of older people with learning disabilities of diet, the opportunity
to smoke and the availability of health screening. We also need to investigate
whether people with specific syndromes associated with learning disabilities
are particularly prone to age-related problems and to dietary or other risk
factors.
Learning disability, ageing and life-expectancy
When considering ageing and how it might affect people with learning
disability, it is important to appreciate that this term refers to a highly
heterogeneous group of people. These people all have evidence of delayed or
abnormal early development together with significant intellectual and
functional impairments, but they may differ markedly in terms of the cause,
developmental profile, nature and extent of the impairments and like
all of us, in their personalities and social backgrounds. While a history of
delayed or abnormal childhood development is essential if the label of
learning disability is to be applied, this process of development should
be considered to be lifelong and therefore continuing into later life. At the
most basic level, severe and profound abnormalities of early development have
a marked impact on life expectancy and on age-specific mortality rates.
McGuigan et al (1995)
discussed the complexities of investigating life expectancy among people with
learning disabilities. In their analysis of data taken from learning
disability registers covering three London boroughs and including births from
1896, they calculated standardised mortality ratios (SMRs; the number of
observed deaths divided by the number of expected deaths) for the years
1982-1990. The SMRs were found to be above unity for both men and women with
learning disabilities; in some groups they were significantly greater. The
main limitation of the study was that the numbers were insufficient to allow
classification according to severity or cause of disability. The cause of the
learning disability is particularly relevant, because one of the groups most
studied is people with Down's syndrome. In this syndrome the presence of
trisomy 21 not only affects the early developmental profile of the child but
is also associated with apparent premature ageing and an increased risk for
developing Alzheimer's disease much earlier in life when compared with people
with other causes of learning disability or with the general population. At
biological, psychological and social levels such observations raise profound
questions about the process of ageing, and the links between disorders of
childhood development and later life and, most importantly, about the
extent to which people with learning disabilities have an increased morbidity
and mortality, and why.
For the above reasons, the issues relating to ageing are more complex in the case of people with learning disabilities. While old age in the general population is clearly associated with increasing levels of disability, this is not, contrary to expectation, the case for people with learning disabilities as a group. This is because there are differential mortality rates depending on the severity of the learning disability. People with more severe learning disabilities still have a reduced life expectancy; therefore, across the spectrum of disability, there is a less severe level of learning disability in the group as a whole with increasing age (Moss, 1991). Table 1 (from Fryers, 1991) illustrates this. Age-specific prevalence rates of learning disability increase during early childhood as the extent of an individual's disability becomes apparent, but in later life they diminish because of the earlier death of those with more profound disabilities. The extent to which physical disabilities contribute to age-related morbidity in people with learning disability is well summarised in the review by Day & Jancar (1994). The studies they reviewed all report increasing prevalence of musculo-skeletal, cardiovascular, respiratory and neoplastic illnesses with age. However, in the case of some disorders (e.g. neoplasia), age-related increases in prevalence are relatively small. The studies did not clearly divide according to the level of learning disability.
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Maaskant et al (1996) undertook a prospective cohort study of 1602 people resident in local facilities for people with learning disability, and looked for changes in care dependency over three years. They found what might have been predicted: that significant change over the period took place only in the younger group, who improved (people with Down's syndrome were excluded), and in those over 60, who deteriorated in terms of care needs. These and other studies indicate that at an individual level increasing age after 60 brings with it the expected age-related impairments but, as described earlier, older people with learning disability when considered as a group have higher levels of functional abilities than the younger group (and lower levels of challenging behaviour) (Moss, 1991). In Maaskant et al's (1996) study, rates of epilepsy were shown to be reduced in the older people with learning disabilities when compared with the younger ones. Importantly, however, sensory impairments characteristically associated with later life are found to a greater extent in those people with learning disabilities aged over 65 (Janicki et al, 1985; Evenhuis, 1995a,b). The various studies indicate that in later life there is a convergence in terms of health and social care needs between people with learning disability and the general population.
However, the study of age-related changes in older people with learning disabilities is complicated by the potential for very significant cohort effects; care therefore has to be taken when extrapolating from present-day findings to the future. For example, mortality rates and educational opportunities were very different 60 years ago than they are today. Infant mortality would have been higher and neonatal care unknown. In particular, those people with more severe learning disabilities who survived childhood are likely to have been self-selected on the basis of their ability to survive despite their disability, and may well therefore have carried with them into adult life a robustness, the effects of which may continue into old age. However, for most there would have been a much greater chance of being placed into an institutional setting, while many may not have received formal education, which did not have to be provided until the passing of the 1971 Education Act.
To summarise, the main biological and functional aspects of ageing are as follows:
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AGEING AND THE MENTAL HEALTH OF PEOPLE WITH LEARNING DISABILITY |
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DEMENTIA AND ITS DIAGNOSIS IN PEOPLE WITH LEARNING DISABILITY |
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In a study of 101 people with learning disabilities aged 50 and over that found 12 people with dementia, the presence of dementia was found to be associated with additional physical health problems and a greater proneness to violence and behavioural problems (Moss & Patel, 1997). The authors pointed out that it is not simply the cognitive decline that is leading to functional decline, but a combination of factors. Interventions need to be targeted not only on issues relating to the dementia but also on those relating to physical health and environment. Dementia is particularly relevant in people with Down's syndrome. This matter is covered in more detail below.
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THE SPECIAL CASE OF PEOPLE WITH DOWN'S SYNDROME |
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Although it was recognised over 100 years ago that people with Down's
syndrome may get a sort of precipitated senility, the understanding of this
relationship was for a long time a largely neuropathological one. Numerous
studies reported evidence of plaques and neurofibrillary tangles in people
with Down's syndrome who had died in early adult life. Some studies
retrospectively looked for evidence of decline and reported evidence of
personality changes, functional decline and the presence of neurological
dysfunction (Oliver & Holland,
1986). This was followed by cross-sectional clinical studies, and
later by more robust data about the likely age-related prevalence of clinical
dementia (i.e. Alzheimer's disease). The neuropathological studies seemed to
indicate that everyone with Down's syndrome developed significant
Alzheimer-like neuropathology as early as their 30s, yet as the clinical
studies were undertaken it became apparent that there were people with Down's
syndrome living into their 50s and 60s who were clearly not developing
dementia. This apparent discrepancy is now well established and remains an
important research issue. Clearly, there are factors which both increase and
decrease the risk of developing Alzheimer's disease with age. The most
striking is the influence of the Apo alleles. The effect is the same as
that found in the general population, with the Apo
2 protecting and the
Apo
4 allele increasing the risk
(Rubinsztein et al,
2000).
The role of amyloid and excess amyloid production appears to be very significant in understanding the increased risk for Alzheimer's disease in people with Down's syndrome. The discovery that the amyloid gene is localised on chromosome 21 came about because of the known association between Down's syndrome and Alzheimer's disease which suggested that chromosome 21 may be a candidate site for an Alzheimer's disease gene. It is also clear that there is diffuse cerebral amyloid deposition starting early in life and ultimately leading to plaques and tangle formation (Rumble et al, 1989; see also review by Mann, 1993). Given that not all people with Down's syndrome develop Alzheimer's disease it would seem that excess amyloid expression cannot by itself account for the high risk of developing Alzheimer's disease. Furthermore, people with Down's syndrome still have a reduced mean life expectancy compared with the general population (45 v. 75 years) and there has been no adequate explanation for that fact, although the effect of increased oxidative activity due to the presence of the superoxide dismutase gene on chromosome 21 or amyloid deposition leading to Alzheimer's disease and premature death are possible explanations. There remain important research questions that need to be addressed with respect to the link between Down's syndrome and Alzheimer's disease. The ultimate objective of such research is the development of treatments that prevent or at least delay the onset of dementia.
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SOCIAL ASPECTS OF AGEING |
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Also important are the ageing and death of family members and the life histories of families. Increasing age for people with learning disabilities is associated with the loss not only of family members but possibly also information about the person him- or herself. If a person has limited language, how can he or she know about his or her past, likes and dislikes, wishes, etc.? A key aspect of ageing is the preservation of that knowledge, perhaps through the use of life story books and other means. The need for preparation for bereavement and for support after it in people with learning disability is now recognised and can be undertaken with the help of specially prepared books. A study by Hollins & Esterhuyzen (1997) of 50 people who had experienced the death of a parent reported high rates of subsequent behavioural disturbance and emotional distress which were often not recognised as being in response to the loss, indicating that in many cases bereavement is still not taken seriously.
The social aspects of ageing are summarised as follows:
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SERVICES |
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The key health and social care service requirements of older people with learning disabilities are summarised as follows:
In this paper it has been argued that with increasing age there is a convergence in terms of health and social care needs between those with and without disability. In childhood and early adult life, specialist services provide for the health and social care needs of people with learning disabilities. In later life the additional dimension of age-related health problems and the changing social care perspective, in which retirement and leisure take priority over paid employment, become apparent. How then do we resolve such tensions? A report from the Social Services Inspectorate (Harris, 1997) emphasised the importance of strategic planning, a flexible funding system that can accommodate change, close collaboration with other agencies and the availability of health expertise in short, informed and individualised needs-led assessments and care planning.
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Clinical Implications and Limitations |
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LIMITATIONS
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ACKNOWLEDGMENTS |
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REFERENCES |
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Aylward, E., Burt, D., Thorpe, L., et al (1997) Diagnosis of dementia in individuals with intellectual disability: report of the task force for development of criteria for diagnosis of dementia in individuals with mental retardation. Journal of Intellectual Disability Research, 41, 152 -164.[Medline]
Cooper, S.-A. (1997) Epidemiology of psychiatric disorders in elderly compared with younger adults with learning disabilities. British Journal of Psychiatry, 170, 375 -380.[Abstract]
Day, K. & Jancar, J. (1994) Mental and physical health in mental handicap: a review. Journal of Intellectual Disability Research, 38, 257 -264.[Medline]
Evenhuis, H. M. (1995a) Medical aspects of ageing in a population with intellectual disability: I. Visual impairment. Journal of Intellectual Disability Research, 39, 19 -25.[Medline]
Evenhuis, H. M. (1995b) Medical aspects of ageing in a population with intellectual disability: II. Hearing impairment. Journal of Intellectual Disability Research, 39, 27 -33.[Medline]
Fryers, T. (1991) Public health approaches to mental retardation: handicap due to intellectual impairment. In Oxford Textbook of Public Health (eds W.W. Holland, R. Detels & G. Knox), pp. 485-508. Oxford: Oxford University Press.
Harris, J. (1997) Services for Older People with Learning Disabilities. London: Social Service Inspectorate, Department of Health.
Hogg, J. & Lambe, L. (1998) Older People with Learning Disabilities: A Review of the Literature of Residential Services and Family Caregiving. Dundee: White Top Research Unit, University of Dundee.
Holland, A. J., Hon, J., Huppert, F. A., et al (1998) Population-based study of the prevalence and presentation of dementia in adults with Down's syndrome. British Journal of Psychiatry, 172, 493 -498.[Abstract]
Hollins, S. & Esterhuyzen, A. (1997) Bereavement and grief in adults with learning disabilities. British Journal of Psychiatry, 170, 497 -501.[Abstract]
Janicki, M. P., Ackerman, L. & Jacobson, W. (1985) State developmental disabilities/ageing plans and planning for an older developmentally disabled population. Mental Retardation, 23, 297 -301.[Medline]
Janicki, M. P., Heller, T., Seltzer, G., et al (1995) Practice Guidelines for the Clinical Assessment and Care Management of Alzheimer and other Dementias among Adults with Mental Retardation. Washington, DC: American Association on Mental Retardation.
Maaskant, M. A., van den Akker, M., Kessels, A. G. H., et al (1996) Care dependence and activities of daily living in relation to ageing: results of a longitudinal study. Journal of Intellectual Disability Research, 40, 535 -543.[Medline]
Mann, D. M. A. (1993) Association between Alzheimer disease and Down syndrome: neuropathological observation. In Alzheimer Disease, Down Syndrome and their Relationship (eds J. M. Berg, H. Karlinsky & A. J. Holland), pp. 71-92. Oxford: Oxford University Press.
McGuigan, S. M., Hollins, S. & Attard, M. (1995) Age-specific standardized mortality rates in people with learning disability. Journal of Intellectual Disability Research, 39, 527 -531.[Medline]
Moss, S. C. (1991) Age and functional abilities of people with a mental handicap: evidence from the Wessex Mental Handicap Register. Journal of Mental Deficiency Research, 35, 430 -445.[Medline]
Moss, S. C. & Patel, P. (1997) Dementia in older people with intellectual disability: symptoms of physical and mental illness, and levels of adaptive behaviour. Journal of Intellectual Disability Research, 41, 60 -69.[Medline]
Oliver, C. & Holland, A. J. (1986) Down's syndrome and Alzheimer's disease: a review. Psychological Medicine, 16, 307 -322.[Medline]
Oliver, C., Crayton, L., Holland, A., et al (1998) A four year prospective study of age related cognitive change in adults with Down's syndrome. Psychological Medicine, 28, 1365 -1377.[CrossRef][Medline]
Patel, D., Goldberg, D. & Moss, S. (1993) Psychiatric morbidity in older people with moderate and severe learning disability. II: The prevalence study. British Journal of Psychiatry, 163, 481 -491.[Abstract]
Prasher, V. P. & Chung, M. C. (1996) Causes of age-related decline in adaptive behavior of adults with Down syndrome: differential diagnoses of dementia. American Journal of Mental Retardation, 101, 175 -183.[Medline]
Robine, J. M. & Ritchie, K. (1991) Healthy life expectancy: evaluation of global indicator of change in population health. British Medical Journal, 302, 457 -460.[Medline]
Rubinsztein, D. C. (1995) Apolipoprotein E: a review of its roles in lipoprotein metabolism, neuronal growth and repair and as a risk factor for Alzheimer's disease. Psychological Medicine, 25, 223 -229.[Medline]
Rubinsztein, D. C., Hon, J., Stevens, F., et al (2000) ApoE genotype and risk of dementia in Down's syndrome. Neuropsychiatric Genetics, in press.
Rumble, B., Retallack, R., Hilbich, C., et al (1989) Amyloid A4 protein and its precursor in Down's syndrome and Alzheimer's disease. New England Journal of Medicine, 320, 1446 -1452.[Abstract]
Zigman, W., Schupf, N., Haveman, M., et al (1997) The epidemiology of Alzheimer disease in intellectual disability; results and recommendations from an international conference. Journal of Intellectual Disability Research, 41, 76-80.[Medline]
Received for publication July 12, 1999. Revision received September 17, 1999. Accepted for publication September 21, 1999.