Article
Down syndrome and dementia: Is depression a confounder for accurate diagnosis and treatment? Stuart Wark
Journal of Intellectual Disabilities 2014, Vol. 18(4) 305–314 ª The Author(s) 2014 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1744629514552152 jid.sagepub.com
University of New England, Australia
Rafat Hussain University of New England, Australia
Trevor Parmenter University of Sydney; University of New England, Australia Date accepted: 8 August 2014
Abstract The past century has seen a dramatic improvement in the life expectancy of people with Down syndrome. However, research has shown that individuals with Down syndrome now have an increased likelihood of early onset dementia. They are more likely than their mainstream peers to experience other significant co-morbidities including mental health issues such as depression. This case study reports a phenomenon in which three individuals with Down syndrome and dementia are described as experiencing a rebound in their functioning after a clear and sustained period of decline. It is hypothesized that this phenomenon is not actually a reversal of the expected dementia trajectory but is an undiagnosed depression exaggerating the true level of functional decline associated with the dementia. The proactive identification and treatment of depressive symptoms may therefore increase the quality of life of some people with Down syndrome and dementia. Keywords Down syndrome, dementia, depression, functional assessment, case study
Corresponding author: Stuart Wark, University of New England, Elm Ave, Armidale, New South Wales 2351, Australia. Email: [email protected]
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Introduction The increased life expectancy of people with intellectual disability is a phenomenon that is being reported in developed countries around the world (Bittles et al., 2002; Coppus, 2013; Patja et al., 2000). Philosophical models of support based on normalization and social role valorization, combined with improved access to appropriate health interventions, have resulted in increased life expectancy of people with intellectual disability (Haveman et al., 2009). The present generation of individuals with an intellectual disability can now reasonably expect to outlive their parents (Buys et al., 2008), a concept that was unlikely mere decades ago.
Aging with Down syndrome This improvement in life expectancy has been particularly significant for the cohort of people with Down syndrome (Coppus, 2013). Studies have shown that at the start of the early 20th century, a person with Down syndrome had a life expectancy of approximately 10 years; it had increased to nearly 60 by the year 2000 (Carmeli et al., 2004; Glasson et al., 2002). The cohort records of people with Down syndrome in Western Australia show that the age range of the oldest (5%) was between 58 and 73 years (Glasson, 2013). However, it was predicted that the life expectancy for people with Down syndrome would start to plateau as a result of the increased likelihood of early onset dementia-related death in this age-group (Torr et al., 2010). It has been recognized for a number of years that a person with Down syndrome has a statistically higher chance of experiencing early onset dementias such as Alzheimer’s disease, frontotemporal dementia and Lewy body dementia than the mainstream population, with some researchers predicting that up to 70% of people with Down syndrome will develop Alzheimer’s disease by the age of 60 (Dalton et al., 1999; Strydom et al., 2010). It has also been reported that individuals with Down syndrome are more likely than people without Down syndrome to experience other significant comorbidities affecting their quality of life including mental health issues such as depression (Thorpe et al., 2012).
The ‘normal’ trajectory of dementia Reisberg et al. (1982) developed a seven-stage model that described the proposed trajectory of dementia. The Global Deterioration Scale predicts seven different distinct phases that an individual may experience, with each subsequent stage indicative of a decline in cognitive or physical skills after a period of relative stability (Reisberg et al., 1982). Other similar models and assessment tools of dementia progression, such as the Clinical Dementia Rating Scale and the Dementia Severity Rating Scale have also been since developed and used around the world (Morris, 1997; Sansoni et al., 2007). While it is acknowledged that individual functioning will fluctuate over time, most models are predicated on the assumption of an ongoing downward trajectory in personal skills following initial diagnosis until the end point.
Trajectory of dementia in a person with Down syndrome While the association between early onset dementias such as Alzheimer’s disease and Down syndrome has been known for many years (Janicki and Dalton, 1999), there still remains considerable uncertainty regarding the clinical progression of such comorbidities (Glasson et al., 2013). This is particularly relevant in relation to the various types of dementia, as there is a lack of validated assessment tools developed specifically for the cohort of people with Down syndrome (Oliver et al., 2011). It was noted by Carr and Collins (2014) that there was a strong need to both
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identify the trajectory of decline in individuals with Down syndrome and distinguish between early stage dementia and normal aging. Both government and disability service providers in Australia are currently working under the assumption that individuals with Down syndrome and diagnosed dementia will follow a downward trajectory over time, a pattern that is similar to that evident within the mainstream population with dementia (Parmenter et al., 2008). However, a rarely reported phenomenon may indicate that the personal cognition and health decline trajectory for a person with Down syndrome and dementia cannot be considered always to be equivalent to the mainstream. It has been argued that some individuals with Down syndrome and formally diagnosed with Alzheimer’s disease have actually seen a complete reversal of symptoms (Burt et al., 1996; Geyde, 1995, cited in Nieuwenhuis-Mark, 2009), as opposed to a limited ‘bounce’ factor more associated with normal day-to-day fluctuations in functioning. There is a paucity of research that has specifically examined this premise of a return in functioning to prediagnosis of dementia levels. The authors of this article were approached by a nongovernment disability organization with a request to specifically examine the possibility of this phenomenon. The organization identified three separate cases in which a person with Down syndrome had been formally diagnosed with dementia but, after an extended period of observable decline, had then apparently returned to pre-diagnosis functioning. It is worth noting that this same phenomenon had not been identified by the organization in any individuals aging with an intellectual disability from causes other than Down syndrome. When the first case (male) was observed, it was simply assumed by the organization that the initial diagnosis of dementia was made prematurely. A second case (female) was identified, and it was again thought to be the result of inaccurate observation and reporting of symptoms by care staff. However, when a third case (male) was reported, it prompted a closer consideration of whether these three cases actually represented a dementia trajectory specific to individuals with Down syndrome or if it was simply a coincidence arising from mistaken observations and subsequent diagnoses. The nominated goal of the organization was to establish whether the individuals were, as it appeared, actually recovering from dementia or whether there were other factors at play that could therefore impact upon any future treatment and support provision for individuals with Down syndrome. The purpose of this study is to examine whether there were any similarities across the three cases, to establish any shared characteristics that may allow for identification of similar cases, and consider the implications for future support for people with Down syndrome.
Methodology The procedures followed for this project were reviewed and ethical approval was granted by the organization’s Research and Clinical Governance Committee. A case review on each of the three individuals identified by the organization was undertaken and conducted in line with a descriptive case-study approach (Yin, 2009). Case studies entail the researcher undertaking an in-depth examination of specific singular events or individuals and occur normally over an extended period of time (Thomas, 2011). The model used in the current research is based upon the available documentation and verbal description of support being provided by the organization and the real-life outcomes that transpired. Each of the three individuals, two male and one female, were identified by the organization due to a unique factor in the dementia trajectory, they all were reported to have had a return to ‘perceived’ pre-diagnosis functioning for a period of time exceeding 6 months. A linear analytic structure (Yin, 2009) was utilized for the analysis, with an in-depth examination of the trajectory of each individual both immediately prior to and following their diagnosis
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with dementia. All case files, including medical reports, were reviewed and key staff members who had worked with the individuals were interviewed to establish the history and time lines relating to the medical history, diagnoses of illness, and any reported changes in functioning. The purpose of this analysis was to establish the key features of each case and whether any shared characteristics could be identified that exemplify this type of dementia trajectory.
Results The case study approach revealed a number of differences and similarities across the three individuals. There were no commonalities in relation to medications taken by these three individuals. In fact, with the exception of one individual taking epilepsy medication, the three cases featured minimal use of prescription medications other than for specific short-term health conditions. None of the three individuals had an identified mental health issue such as depression or anxiety; they were not being treated for any form of cancer and did not have any serious long-term health diagnoses other than Alzheimer’s disease and the aforementioned epilepsy. The key common features were that each individual: had Down syndrome; was aged in their late 40s or 50s when the diagnosis of dementia was formally made; had reasonably high levels of personal skills prior to diagnosis (e.g. had functional communication skills, lived semi-independently, and worked either in open or in supported environment); experienced a significant decline in personal functioning that led to a formal medical diagnosis of dementia; underwent a significant ‘life event’ after the diagnosis of dementia; saw a ‘rebound’ (a term used by the organization) or return to what family and carers believed to be pre-diagnosis functioning after the significant life event; maintained the higher level of functioning for a period of at least 6 months; and then experienced a very significant and sudden decline in a short period of time. One of the key shared features was a significant life event during the initial stages of functional decline that resulted in a major change in their daily routine and a subsequent redemonstration of skills that were thought to be lost. These life events were not always positive in the first instance; in fact, they may have involved a quite traumatic loss such as the death of a lifelong carer or the transition from a very familiar home to a new environment. However, in each case the life event also resulted in a long-term positive outcome such as increased opportunities for socialization with peers. An attempt was made to map the trajectory of the dementia based upon the key shared features of the three individuals. While someone from the mainstream community may expect to see an ongoing decline over a period of years interspersed with periods of relative stability, all three individuals demonstrated a substantial rebound in their skills in the few months following a significant life event. Figure 1 shows a simplistic decline for the general population in line with Reisberg et al.’s (1982) model of dementia, whereas Figure 2 demonstrates the decline described for the three cases. As can be seen in Figure 2, the timeline mapping exercise revealed that the significant life event preceded the rebound to pre-diagnosis functioning and occurred at a point prior to the mainstream model’s moderately severe decline phase. Each individual then experienced a prolonged period of
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Level of functioning
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Figure 1. Functional decline over time for the general population with dementia.
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Figure 2. Functional decline over time for the three described cases.
functioning at a perceived pre-diagnosis level, and in one case, the carers argued that the individual experienced the highest ever quality of life. However, in each case, the individual then had a sudden and rapid decline at a much steeper rate than previously experienced. It was considered that the end point had occurred across approximately the expected time span of between 6 and 8 years as with the predicted population trajectory (Silverman, 2010), but the differentiating feature was relatively a long rebound period prior to a substantial decline in a short period of time.
Discussion The identification of these apparent common features across the three cases led to an examination of the literature and the recognition that this rebound phenomenon had been
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previously reported (e.g. Burt et al., 1996; Geyde, 1995, cited in Nieuwenhuis-Mark, 2009). Discussions with disability service providers have indicated that this rebound phenomenon has been observed not just in Australia but also elsewhere in the world. During June–August 2013, the lead author undertook a Churchill Fellowship tour of the United States, Ireland, and the United Kingdom. During this study tour, a variety of disability support services were visited and key staff were asked whether they had ever seen or heard of individuals whose case history presented with key features similar to those described in the above Results’ section. While the majority of those interviewed indicated that they had not witnessed anyone who matched this model, three different organizations—one each in Ireland, Scotland and England—did identify that they had observed cases of a ‘rebound phenomenon’ in people with Down syndrome. While this limited evidence is hardly conclusive, it raises the possibility that there may be an intervention or support to increase the quality of life for some individuals with Down syndrome after dementia has been diagnosed. It is worth noting that the majority of people with Down syndrome and dementia do not appear to experience this same rebound in functioning. What is not clear is whether the observed difference in the three cases was simply due to an inaccurate diagnosis or whether there are additional confounding factors that affect some individuals with Down syndrome which can result in this different dementia trajectory.
Is the assessment of dementia in Down syndrome reliable? The immediate conclusion that can be drawn when considering the described rebound phenomenon is that the initial diagnosis was incorrect. There are clearly problems associated with accurately diagnosing dementia in individuals with Down syndrome including fluctuating performance (Krinsky-McHale et al., 2008), differing classification and diagnostic criteria (Strydom et al., 2007), a lack of baseline data for comparative purposes (Nieuwenhuis-Mark, 2009), and a tendency for clinicians to overdiagnose dementia in adults with Down syndrome (Burt et al., 2005). All of these concerns highlight the potential that none of the cases in which the individual with Down syndrome returned to perceived pre-diagnosis functioning actually had dementia at the time of the rebound. One of the features of both the Australian and overseas examples was that the initial diagnosis of dementia occurred when the individual was in their 40s or 50s. It has been proposed that the vast majority of individuals with Down syndrome over the age of 35 will display neuropathological signs of dementia (Nieuwenhuis-Mark, 2009), and a tendency for some clinicians to ascribe any behavioral changes within this cohort to premature aging has been observed (Acquilano et al., 2007). This argument may support the concept that the initial diagnosis was made incorrectly and in accordance with a preconceived belief of emerging dementia rather than through appropriate consideration of any other possibilities. However, each of the three individuals had shown early signs of functional decline and did ultimately progress to end point dementia in a time frame that aligned with expectations for a person with Down syndrome. This would tend to support the initial diagnosis of dementia as being accurate. One main differential point appears to lie around the factor of a significant life event occurring prior to the stage of moderately severe decline. In each case, a major change to daily living occurred, and soon afterward a rebound to pre-diagnosis functioning was reported. This similarity in the cases would appear to point to a combination of environmental and social factors that could have contributed to the rebound phenomenon.
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Depression, Down syndrome, and dementia Some studies have argued that people with Down syndrome are more likely to experience depression than the mainstream (Collacott et al., 1992); however, the research evidence is currently not conclusive with rates reported between 0% and 11% (Walker et al., 2011). Nonetheless, it is apparent that people with Down syndrome do experience depression, and this fact is relevant with respect to the reported incidence of depressive states in people with Alzheimer’s disease (Devanand et al., 1996). It is possible that the three individuals with Down syndrome who apparently rebounded in function did in fact have early stage dementia, but the overall severity of the dementia symptoms was clouded by an undiagnosed depressive incident. None of the three cases had depression formally diagnosed or treated, but current analysis of the case notes indicates possible symptoms of a depression such as withdrawal, low energy levels, and sadness may have been potentially misascribed to being part of the identified dementia. Depression does not appear to have been considered in the cases. In each of the cases, it is hypothesized that the major life event may have managed to ‘break’ the unrecognized depression, and, therefore, the individual appeared to make a return to pre-diagnosis functioning. In fact, the existing dementia may have seen the individual operating at lower levels than pre-diagnosis, but once the overarching depression had been removed and functioning rebounded, the observers incorrectly thought the individual had made a complete recovery. This possibility has considerable clinical implications. In particular, it raises the potential for the quality of life for people with Down syndrome and dementia to be greatly improved if a depression is both diagnosed and treated appropriately during the early stages. The three cases described are those identified following a perceived rebound in functioning. It is possible that there are currently individuals with Down syndrome whose quality of life could see a similar rebound if the hypothesis of an undiagnosed depression is accurate and appropriate treatment could be provided. Both drug interventions and various types of psychological counseling have been shown to be effective for people with Down syndrome and intellectual disabilities (e.g. Walker et al., 2011; Wark, 2012). If depression is an overarching issue for some individuals that masks the true level of decline associated with dementia, further research is required into the actual types of depression experienced by people with Down syndrome. Current research indicates that depression is not a simplistic unitary construct and that there are different subtypes of depression with differing neurobiological pathways associated with these subtypes of depression (e.g. Sharpley and Bitsika, 2013). Therefore, there is also further work needed to examine the subtypes of depression individuals with Down syndrome experience in order to better ascertain the best treatment pathways.
Future research All three individuals who experienced a rebound in functioning did so following a significant life event during earlier stages of dementia. On the basis of this preliminary data, it is perceived that any intervention should therefore occur during the beginning stages of dementia, after formal diagnosis but before moderately severe decline has occurred. More comprehensive research is required to examine the trajectory of Down syndrome and dementia across a wide cohort of individuals and to carefully track the rate of decline while also simultaneously considering any underlying depression. Many services have now started to follow the recommendation of annual screening to establish a baseline function for adults with Down syndrome over the age of 35
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(Glasson et al., 2013). If this practice becomes widespread, it will facilitate future research as more comprehensive data sets will start to become available and analysis of the dementia trajectory and the identification of an associated depression will become easier.
Limitations This report is based upon limited data, and it is acknowledged that there remains the potential that the cases are merely an example of coincidence gathered from a large enough sample. Another significant problem in trying to develop a comprehensive case review is that often organizations have minimal historical quantitative information based upon objective testing. For example, none of the three individuals in the current review had ever had an intelligence quotient test and only minimal functioning assessments. When questioned upon this omission, the explanation from the organization was that people with Down syndrome often were not tested in the past as it was considered ‘self-evident’ that they had a disability and such testing was therefore unnecessary. They had all entered the service as young children, and the need for such testing was then considered irrelevant as the focus was upon supporting the individual’s demonstrated needs. Similarly, much of the historical information was gathered from case notes and verbal feedback rather than more objective functional measurement tools that were either not available or not utilized.
Conclusions While the current research has acknowledged limitations, the fact that the rebound phenomenon has been evidenced in different countries does indicate that additional research would be desirable to establish whether there is an intervention that could be implemented to better support some people with Down syndrome and dementia. While it is not possible to draw any solid conclusions on the basis of the limited data, there are indications that proactively identifying and treating depressive symptoms may increase the quality of life in some people with Down syndrome and early stage dementia. Funding This research received no specific grant from any funding agency in the public, commercial or not-for profit sectors.
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Down syndrome and dementia: Is depression a confounder for accurate diagnosis and treatment? Stuart Wark
Journal of Intellectual Disabilities 2014, Vol. 18(4) 305–314 ª The Author(s) 2014 Reprints and permission: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/1744629514552152 jid.sagepub.com
University of New England, Australia
Rafat Hussain University of New England, Australia
Trevor Parmenter University of Sydney; University of New England, Australia Date accepted: 8 August 2014
Abstract The past century has seen a dramatic improvement in the life expectancy of people with Down syndrome. However, research has shown that individuals with Down syndrome now have an increased likelihood of early onset dementia. They are more likely than their mainstream peers to experience other significant co-morbidities including mental health issues such as depression. This case study reports a phenomenon in which three individuals with Down syndrome and dementia are described as experiencing a rebound in their functioning after a clear and sustained period of decline. It is hypothesized that this phenomenon is not actually a reversal of the expected dementia trajectory but is an undiagnosed depression exaggerating the true level of functional decline associated with the dementia. The proactive identification and treatment of depressive symptoms may therefore increase the quality of life of some people with Down syndrome and dementia. Keywords Down syndrome, dementia, depression, functional assessment, case study
Corresponding author: Stuart Wark, University of New England, Elm Ave, Armidale, New South Wales 2351, Australia. Email: [email protected]
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Introduction The increased life expectancy of people with intellectual disability is a phenomenon that is being reported in developed countries around the world (Bittles et al., 2002; Coppus, 2013; Patja et al., 2000). Philosophical models of support based on normalization and social role valorization, combined with improved access to appropriate health interventions, have resulted in increased life expectancy of people with intellectual disability (Haveman et al., 2009). The present generation of individuals with an intellectual disability can now reasonably expect to outlive their parents (Buys et al., 2008), a concept that was unlikely mere decades ago.
Aging with Down syndrome This improvement in life expectancy has been particularly significant for the cohort of people with Down syndrome (Coppus, 2013). Studies have shown that at the start of the early 20th century, a person with Down syndrome had a life expectancy of approximately 10 years; it had increased to nearly 60 by the year 2000 (Carmeli et al., 2004; Glasson et al., 2002). The cohort records of people with Down syndrome in Western Australia show that the age range of the oldest (5%) was between 58 and 73 years (Glasson, 2013). However, it was predicted that the life expectancy for people with Down syndrome would start to plateau as a result of the increased likelihood of early onset dementia-related death in this age-group (Torr et al., 2010). It has been recognized for a number of years that a person with Down syndrome has a statistically higher chance of experiencing early onset dementias such as Alzheimer’s disease, frontotemporal dementia and Lewy body dementia than the mainstream population, with some researchers predicting that up to 70% of people with Down syndrome will develop Alzheimer’s disease by the age of 60 (Dalton et al., 1999; Strydom et al., 2010). It has also been reported that individuals with Down syndrome are more likely than people without Down syndrome to experience other significant comorbidities affecting their quality of life including mental health issues such as depression (Thorpe et al., 2012).
The ‘normal’ trajectory of dementia Reisberg et al. (1982) developed a seven-stage model that described the proposed trajectory of dementia. The Global Deterioration Scale predicts seven different distinct phases that an individual may experience, with each subsequent stage indicative of a decline in cognitive or physical skills after a period of relative stability (Reisberg et al., 1982). Other similar models and assessment tools of dementia progression, such as the Clinical Dementia Rating Scale and the Dementia Severity Rating Scale have also been since developed and used around the world (Morris, 1997; Sansoni et al., 2007). While it is acknowledged that individual functioning will fluctuate over time, most models are predicated on the assumption of an ongoing downward trajectory in personal skills following initial diagnosis until the end point.
Trajectory of dementia in a person with Down syndrome While the association between early onset dementias such as Alzheimer’s disease and Down syndrome has been known for many years (Janicki and Dalton, 1999), there still remains considerable uncertainty regarding the clinical progression of such comorbidities (Glasson et al., 2013). This is particularly relevant in relation to the various types of dementia, as there is a lack of validated assessment tools developed specifically for the cohort of people with Down syndrome (Oliver et al., 2011). It was noted by Carr and Collins (2014) that there was a strong need to both
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identify the trajectory of decline in individuals with Down syndrome and distinguish between early stage dementia and normal aging. Both government and disability service providers in Australia are currently working under the assumption that individuals with Down syndrome and diagnosed dementia will follow a downward trajectory over time, a pattern that is similar to that evident within the mainstream population with dementia (Parmenter et al., 2008). However, a rarely reported phenomenon may indicate that the personal cognition and health decline trajectory for a person with Down syndrome and dementia cannot be considered always to be equivalent to the mainstream. It has been argued that some individuals with Down syndrome and formally diagnosed with Alzheimer’s disease have actually seen a complete reversal of symptoms (Burt et al., 1996; Geyde, 1995, cited in Nieuwenhuis-Mark, 2009), as opposed to a limited ‘bounce’ factor more associated with normal day-to-day fluctuations in functioning. There is a paucity of research that has specifically examined this premise of a return in functioning to prediagnosis of dementia levels. The authors of this article were approached by a nongovernment disability organization with a request to specifically examine the possibility of this phenomenon. The organization identified three separate cases in which a person with Down syndrome had been formally diagnosed with dementia but, after an extended period of observable decline, had then apparently returned to pre-diagnosis functioning. It is worth noting that this same phenomenon had not been identified by the organization in any individuals aging with an intellectual disability from causes other than Down syndrome. When the first case (male) was observed, it was simply assumed by the organization that the initial diagnosis of dementia was made prematurely. A second case (female) was identified, and it was again thought to be the result of inaccurate observation and reporting of symptoms by care staff. However, when a third case (male) was reported, it prompted a closer consideration of whether these three cases actually represented a dementia trajectory specific to individuals with Down syndrome or if it was simply a coincidence arising from mistaken observations and subsequent diagnoses. The nominated goal of the organization was to establish whether the individuals were, as it appeared, actually recovering from dementia or whether there were other factors at play that could therefore impact upon any future treatment and support provision for individuals with Down syndrome. The purpose of this study is to examine whether there were any similarities across the three cases, to establish any shared characteristics that may allow for identification of similar cases, and consider the implications for future support for people with Down syndrome.
Methodology The procedures followed for this project were reviewed and ethical approval was granted by the organization’s Research and Clinical Governance Committee. A case review on each of the three individuals identified by the organization was undertaken and conducted in line with a descriptive case-study approach (Yin, 2009). Case studies entail the researcher undertaking an in-depth examination of specific singular events or individuals and occur normally over an extended period of time (Thomas, 2011). The model used in the current research is based upon the available documentation and verbal description of support being provided by the organization and the real-life outcomes that transpired. Each of the three individuals, two male and one female, were identified by the organization due to a unique factor in the dementia trajectory, they all were reported to have had a return to ‘perceived’ pre-diagnosis functioning for a period of time exceeding 6 months. A linear analytic structure (Yin, 2009) was utilized for the analysis, with an in-depth examination of the trajectory of each individual both immediately prior to and following their diagnosis
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with dementia. All case files, including medical reports, were reviewed and key staff members who had worked with the individuals were interviewed to establish the history and time lines relating to the medical history, diagnoses of illness, and any reported changes in functioning. The purpose of this analysis was to establish the key features of each case and whether any shared characteristics could be identified that exemplify this type of dementia trajectory.
Results The case study approach revealed a number of differences and similarities across the three individuals. There were no commonalities in relation to medications taken by these three individuals. In fact, with the exception of one individual taking epilepsy medication, the three cases featured minimal use of prescription medications other than for specific short-term health conditions. None of the three individuals had an identified mental health issue such as depression or anxiety; they were not being treated for any form of cancer and did not have any serious long-term health diagnoses other than Alzheimer’s disease and the aforementioned epilepsy. The key common features were that each individual: had Down syndrome; was aged in their late 40s or 50s when the diagnosis of dementia was formally made; had reasonably high levels of personal skills prior to diagnosis (e.g. had functional communication skills, lived semi-independently, and worked either in open or in supported environment); experienced a significant decline in personal functioning that led to a formal medical diagnosis of dementia; underwent a significant ‘life event’ after the diagnosis of dementia; saw a ‘rebound’ (a term used by the organization) or return to what family and carers believed to be pre-diagnosis functioning after the significant life event; maintained the higher level of functioning for a period of at least 6 months; and then experienced a very significant and sudden decline in a short period of time. One of the key shared features was a significant life event during the initial stages of functional decline that resulted in a major change in their daily routine and a subsequent redemonstration of skills that were thought to be lost. These life events were not always positive in the first instance; in fact, they may have involved a quite traumatic loss such as the death of a lifelong carer or the transition from a very familiar home to a new environment. However, in each case the life event also resulted in a long-term positive outcome such as increased opportunities for socialization with peers. An attempt was made to map the trajectory of the dementia based upon the key shared features of the three individuals. While someone from the mainstream community may expect to see an ongoing decline over a period of years interspersed with periods of relative stability, all three individuals demonstrated a substantial rebound in their skills in the few months following a significant life event. Figure 1 shows a simplistic decline for the general population in line with Reisberg et al.’s (1982) model of dementia, whereas Figure 2 demonstrates the decline described for the three cases. As can be seen in Figure 2, the timeline mapping exercise revealed that the significant life event preceded the rebound to pre-diagnosis functioning and occurred at a point prior to the mainstream model’s moderately severe decline phase. Each individual then experienced a prolonged period of
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Level of functioning
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Figure 2. Functional decline over time for the three described cases.
functioning at a perceived pre-diagnosis level, and in one case, the carers argued that the individual experienced the highest ever quality of life. However, in each case, the individual then had a sudden and rapid decline at a much steeper rate than previously experienced. It was considered that the end point had occurred across approximately the expected time span of between 6 and 8 years as with the predicted population trajectory (Silverman, 2010), but the differentiating feature was relatively a long rebound period prior to a substantial decline in a short period of time.
Discussion The identification of these apparent common features across the three cases led to an examination of the literature and the recognition that this rebound phenomenon had been
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previously reported (e.g. Burt et al., 1996; Geyde, 1995, cited in Nieuwenhuis-Mark, 2009). Discussions with disability service providers have indicated that this rebound phenomenon has been observed not just in Australia but also elsewhere in the world. During June–August 2013, the lead author undertook a Churchill Fellowship tour of the United States, Ireland, and the United Kingdom. During this study tour, a variety of disability support services were visited and key staff were asked whether they had ever seen or heard of individuals whose case history presented with key features similar to those described in the above Results’ section. While the majority of those interviewed indicated that they had not witnessed anyone who matched this model, three different organizations—one each in Ireland, Scotland and England—did identify that they had observed cases of a ‘rebound phenomenon’ in people with Down syndrome. While this limited evidence is hardly conclusive, it raises the possibility that there may be an intervention or support to increase the quality of life for some individuals with Down syndrome after dementia has been diagnosed. It is worth noting that the majority of people with Down syndrome and dementia do not appear to experience this same rebound in functioning. What is not clear is whether the observed difference in the three cases was simply due to an inaccurate diagnosis or whether there are additional confounding factors that affect some individuals with Down syndrome which can result in this different dementia trajectory.
Is the assessment of dementia in Down syndrome reliable? The immediate conclusion that can be drawn when considering the described rebound phenomenon is that the initial diagnosis was incorrect. There are clearly problems associated with accurately diagnosing dementia in individuals with Down syndrome including fluctuating performance (Krinsky-McHale et al., 2008), differing classification and diagnostic criteria (Strydom et al., 2007), a lack of baseline data for comparative purposes (Nieuwenhuis-Mark, 2009), and a tendency for clinicians to overdiagnose dementia in adults with Down syndrome (Burt et al., 2005). All of these concerns highlight the potential that none of the cases in which the individual with Down syndrome returned to perceived pre-diagnosis functioning actually had dementia at the time of the rebound. One of the features of both the Australian and overseas examples was that the initial diagnosis of dementia occurred when the individual was in their 40s or 50s. It has been proposed that the vast majority of individuals with Down syndrome over the age of 35 will display neuropathological signs of dementia (Nieuwenhuis-Mark, 2009), and a tendency for some clinicians to ascribe any behavioral changes within this cohort to premature aging has been observed (Acquilano et al., 2007). This argument may support the concept that the initial diagnosis was made incorrectly and in accordance with a preconceived belief of emerging dementia rather than through appropriate consideration of any other possibilities. However, each of the three individuals had shown early signs of functional decline and did ultimately progress to end point dementia in a time frame that aligned with expectations for a person with Down syndrome. This would tend to support the initial diagnosis of dementia as being accurate. One main differential point appears to lie around the factor of a significant life event occurring prior to the stage of moderately severe decline. In each case, a major change to daily living occurred, and soon afterward a rebound to pre-diagnosis functioning was reported. This similarity in the cases would appear to point to a combination of environmental and social factors that could have contributed to the rebound phenomenon.
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Depression, Down syndrome, and dementia Some studies have argued that people with Down syndrome are more likely to experience depression than the mainstream (Collacott et al., 1992); however, the research evidence is currently not conclusive with rates reported between 0% and 11% (Walker et al., 2011). Nonetheless, it is apparent that people with Down syndrome do experience depression, and this fact is relevant with respect to the reported incidence of depressive states in people with Alzheimer’s disease (Devanand et al., 1996). It is possible that the three individuals with Down syndrome who apparently rebounded in function did in fact have early stage dementia, but the overall severity of the dementia symptoms was clouded by an undiagnosed depressive incident. None of the three cases had depression formally diagnosed or treated, but current analysis of the case notes indicates possible symptoms of a depression such as withdrawal, low energy levels, and sadness may have been potentially misascribed to being part of the identified dementia. Depression does not appear to have been considered in the cases. In each of the cases, it is hypothesized that the major life event may have managed to ‘break’ the unrecognized depression, and, therefore, the individual appeared to make a return to pre-diagnosis functioning. In fact, the existing dementia may have seen the individual operating at lower levels than pre-diagnosis, but once the overarching depression had been removed and functioning rebounded, the observers incorrectly thought the individual had made a complete recovery. This possibility has considerable clinical implications. In particular, it raises the potential for the quality of life for people with Down syndrome and dementia to be greatly improved if a depression is both diagnosed and treated appropriately during the early stages. The three cases described are those identified following a perceived rebound in functioning. It is possible that there are currently individuals with Down syndrome whose quality of life could see a similar rebound if the hypothesis of an undiagnosed depression is accurate and appropriate treatment could be provided. Both drug interventions and various types of psychological counseling have been shown to be effective for people with Down syndrome and intellectual disabilities (e.g. Walker et al., 2011; Wark, 2012). If depression is an overarching issue for some individuals that masks the true level of decline associated with dementia, further research is required into the actual types of depression experienced by people with Down syndrome. Current research indicates that depression is not a simplistic unitary construct and that there are different subtypes of depression with differing neurobiological pathways associated with these subtypes of depression (e.g. Sharpley and Bitsika, 2013). Therefore, there is also further work needed to examine the subtypes of depression individuals with Down syndrome experience in order to better ascertain the best treatment pathways.
Future research All three individuals who experienced a rebound in functioning did so following a significant life event during earlier stages of dementia. On the basis of this preliminary data, it is perceived that any intervention should therefore occur during the beginning stages of dementia, after formal diagnosis but before moderately severe decline has occurred. More comprehensive research is required to examine the trajectory of Down syndrome and dementia across a wide cohort of individuals and to carefully track the rate of decline while also simultaneously considering any underlying depression. Many services have now started to follow the recommendation of annual screening to establish a baseline function for adults with Down syndrome over the age of 35
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(Glasson et al., 2013). If this practice becomes widespread, it will facilitate future research as more comprehensive data sets will start to become available and analysis of the dementia trajectory and the identification of an associated depression will become easier.
Limitations This report is based upon limited data, and it is acknowledged that there remains the potential that the cases are merely an example of coincidence gathered from a large enough sample. Another significant problem in trying to develop a comprehensive case review is that often organizations have minimal historical quantitative information based upon objective testing. For example, none of the three individuals in the current review had ever had an intelligence quotient test and only minimal functioning assessments. When questioned upon this omission, the explanation from the organization was that people with Down syndrome often were not tested in the past as it was considered ‘self-evident’ that they had a disability and such testing was therefore unnecessary. They had all entered the service as young children, and the need for such testing was then considered irrelevant as the focus was upon supporting the individual’s demonstrated needs. Similarly, much of the historical information was gathered from case notes and verbal feedback rather than more objective functional measurement tools that were either not available or not utilized.
Conclusions While the current research has acknowledged limitations, the fact that the rebound phenomenon has been evidenced in different countries does indicate that additional research would be desirable to establish whether there is an intervention that could be implemented to better support some people with Down syndrome and dementia. While it is not possible to draw any solid conclusions on the basis of the limited data, there are indications that proactively identifying and treating depressive symptoms may increase the quality of life in some people with Down syndrome and early stage dementia. Funding This research received no specific grant from any funding agency in the public, commercial or not-for profit sectors.
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