**3. Wider impact of LBD**

Both PD and LBD have a significant impact on the person with the condition, their life partner, and family, as well as on society, due to higher needs and dependency as a result of developing the illness. For the person with the condition, the progression of PD can worsen their health-related quality [27], particularly physical and social functioning, cognition, communication and emotional well-being [28]. The notion of adverse impact of PD on physical, social and role functioning is corroborated by a qualitative study which found that PD brings about many changes in emotions and feelings, including fears and uncertainty about the future but also highlights some benefits that PD may bring [29]. Despite the well-established association between subjective well-being and motor impairment, there is a growing literature suggesting that more emphasis should be paid to the positive aspects of well-being, specifically endorsing social support, socialising with other people with PD, engaging in physical activities and maintaining motor skills can contribute to life satisfaction, sense of accomplishment, autonomy and positive emotions in people with PD [27]. This suggests that future studies could focus on life satisfaction and psychological well-being, which could potentially diminish the negative impact of PD on the person.

In terms of the wider impact of PD on society, the disease places a major socioeconomic burden with an estimated annual cost of £2 billion in the UK [30]. A recent report on the impact of living with PD revealed that the total financial costs per household exceeded £16,000 per year due to increase in health and social care costs and reduction in income [31]. Many care partners of people with PD also had to give up employment to be able to provide care for their partner, which led to loss of income [32]. As the severity of PD increases, the costs also rise and can be up to six times higher at the advanced stage (i.e. H&Y stage 5) compared to the initial stage (H&Y stage 1) [33]. These costs likely increase with disease progression due to the complexity of concomitant symptoms of PD, the increasing need for a care partner, and increased rate of admission to residential care homes. However, some of the costs could be partially saved by the help, care and support that family care partners provide to people with PD and LBD. Prince and colleagues [1] estimated that care providers save about £11.6 billion in the UK each year, which is increasing faster than the corresponding increase in formal health and social care costs [1].

Cognitive impairment in PD significantly increases the frequency of institutionalisation [34, 35] and increases healthcare costs even more than PD without cognitive impairment [36, 37]. Furthermore, mortality, which is already increased among people with PD compared to the rest of the population [38], increases with the emergence of dementia, which is one of the key predictors of PD-related mortality [36, 37]. The emergence of cognitive impairment can also significantly decrease quality of life of people with PD and increase emotional stress [39].

Similarly to PD and PDD, a diagnosis of DLB can also escalate healthcare costs [7], shorten time to death [7, 40, 41], and accelerate the rate of admission to residential care homes and hospitals [7, 42]. A DLB diagnosis can also lengthen hospital stay and increase hospitalisation costs [43, 44] compared to AD. Mueller et al. [43] explain that this is due to deteriorated physical health and increased neuropsychiatric symptoms in DLB and they conclude that overall people with DLB have a worse prognosis compared to people with AD [15]. Mueller and colleagues [43] estimate that approximately 80,000 people with DLB in the UK will incur over 27,000 hospital admissions, and spend over 300,000 days in hospital that will exceed £35 million in hospitalisation costs in just 1 year, which is higher compared to the equal number of people with AD.

#### **4. Overview of care partners**

Around the world, one person in ten is a care partner [45]. In the UK, there are currently 6.5 million people who provide care and each day 6000 people in addition take on the caring role [46]. Of all the care partners in Great Britain, approximately 11% provide care to someone with dementia in a home setting [47]. Financially, the contribution that care partners make exceeds £132 billion per annum, which surpasses the annual budget of the National Health Service (NHS) in England [48], showing that the help and support that care partners provide is invaluable and has cost saving implications for the health and social care system.

A care partner is an individual, usually a spouse or an adult child, who has taken on the responsibility to help, support and assist a family member who cannot take care of themselves, and to assure they are safe and well [49, 50]. Care provision helps the person with the condition to reach the highest possible functioning in their daily life [49]. Often, the care partner of a person with PD supports with personal, psychological and medical care, assisting with mental and physical exercising, maintaining good nutrition, arranging living conditions and helping with housework [32, 51]. Care partners also coordinate, plan and manage care and look for various interventions and treatments that could potentially alleviate the symptoms of the care recipients [49, 52]. Notably, in addition to providing care, a proportion of care partners may be in part-time or full-time employment [53], which raises complex issues around managing their work and care commitments and may diminish their time and energy to provide care. In addition, care partners may also be older adults themselves and have physical and mental health issues which may limit their capabilities to provide care [51]. As a consequence, care partners, particularly within dementia, may have increased negative feelings, depression, diminished well-being, and neglect their own health [54]. Thus, they become 'the invisible or hidden patients' [52].

Caring and caregiving are considered to be different. Namely, caring is the affective component of 'one's commitment to the welfare of another', whereas caregiving is 'the behavioural expression of this commitment' ([50], p. 583). Likewise, caring has been described as the interplay between emotion and action involving endearing feelings such as love as well as activities involving labour [55]. Caregiving, however, has even been named as the 'unexpected career' due to the sudden onset of this role [56].

The shift into taking on care responsibilities may either be gradual or sudden, although in the case of neurodegenerative conditions such as PDD and DLB, this transition usually occurs gradually. The presenting symptoms of PDD and DLB may be so subtle that care partners may not notice a visible change in their

**39**

domains [65, 70]:

*Long-Term Partnerships in Lewy Body Dementias DOI: http://dx.doi.org/10.5772/intechopen.86204*

receiving care and the person providing it.

both partners when facing a neurodegenerative condition.

1.the transactional model of stress and coping [62];

3.the stress process and coping model [64]; and

2.the two-dimensional model of psychosocial morbidity [63];

These four preceding models take into account the characteristics of each member of the dyad as well as the care recipient's disease symptomatology and care partner's reactions and outcomes. In PD, the Stress Process Model [50] and the PD-specific Stress-Appraisal Model [65] are most applied by scholars. The Stress-Appraisal model [65] has been built on previous similar models [50, 66–69] and has since been developed further following a systematic review which evaluated burden, mental health and quality of life among care partners of people with PD [70]. The proposed adaptations by Greenwell and colleagues [70] are depicted in **Figure 1**.

The adapted PD-specific Stress-Appraisal model [70], which is derived from the Stress-Appraisal model by Goldsworthy and Knowles [65], captures care partners' experiences of care provision in PD (see **Figure 1**) and consists of four main

stress models in dementia [61] are:

4.the stress process model [50].

**5. Theoretical models of dyadic care relationships in PD**

To understand the impact of PD factors on care partners and how they affect care partner well-being and the dyadic relationship, a theoretical framework is required. Such a framework also helps to understand the connections between the variables and to determine the direction of predictors. In the context of dementia, a number of multi-component models have been developed evaluating the factors contributing to caregiving-related stressors [61]. The most common care partner

responsibilities, even though they may have started to help and support the care recipients. Thus, in early stages of the disease, care partners may not identify themselves as carers and may even dislike being called a 'carer' [57–59]. Instead, many people prefer to be acknowledged as a 'spouse', 'partner' or 'support person' [58], highlighting the importance of endorsing the relationship between the person

The involvement of a care partner in the care of their family member is advantageous because they have a unique perspective on the care recipient's condition and thus, can provide a more precise and detailed description of their symptoms [60]. However, the State of Caring 2018 survey in the UK [48] found that 72% of care partners experienced worsening of their mental health and 61% in their physical health due to their caring role. Furthermore, over half of care partners anticipated that both physical and mental health would continue to deteriorate over the coming years, and a third of participants predicted that a decline in their mental and physical health would prevent them from being able to provide care to the care recipients in the future [48]. Brodaty and Donkin [52] contended that including care partners is so imperative that without their help, the quality of life of people with neurodegenerative conditions would drop so much that it would increase admissions to institutional care. However, this comes at the cost of care partners' own quality of life [52] and raises an important question about how to maintain the well-being of

*Long-Term Partnerships in Lewy Body Dementias DOI: http://dx.doi.org/10.5772/intechopen.86204*

*Geriatric Medicine and Gerontology*

**4. Overview of care partners**

people with PD compared to the rest of the population [38], increases with the emergence of dementia, which is one of the key predictors of PD-related mortality [36, 37]. The emergence of cognitive impairment can also significantly decrease

Similarly to PD and PDD, a diagnosis of DLB can also escalate healthcare costs [7], shorten time to death [7, 40, 41], and accelerate the rate of admission to residential care homes and hospitals [7, 42]. A DLB diagnosis can also lengthen hospital stay and increase hospitalisation costs [43, 44] compared to AD. Mueller et al. [43] explain that this is due to deteriorated physical health and increased neuropsychiatric symptoms in DLB and they conclude that overall people with DLB have a worse prognosis compared to people with AD [15]. Mueller and colleagues [43] estimate that approximately 80,000 people with DLB in the UK will incur over 27,000 hospital admissions, and spend over 300,000 days in hospital that will exceed £35 million in hospitalisation costs in just 1 year, which is higher compared to the equal number of people with AD.

Around the world, one person in ten is a care partner [45]. In the UK, there are currently 6.5 million people who provide care and each day 6000 people in addition take on the caring role [46]. Of all the care partners in Great Britain, approximately 11% provide care to someone with dementia in a home setting [47]. Financially, the contribution that care partners make exceeds £132 billion per annum, which surpasses the annual budget of the National Health Service (NHS) in England [48], showing that the help and support that care partners provide is invaluable and has

A care partner is an individual, usually a spouse or an adult child, who has taken on the responsibility to help, support and assist a family member who cannot take care of themselves, and to assure they are safe and well [49, 50]. Care provision helps the person with the condition to reach the highest possible functioning in their daily life [49]. Often, the care partner of a person with PD supports with personal, psychological and medical care, assisting with mental and physical exercising, maintaining good nutrition, arranging living conditions and helping with housework [32, 51]. Care partners also coordinate, plan and manage care and look for various interventions and treatments that could potentially alleviate the symptoms of the care recipients [49, 52]. Notably, in addition to providing care, a proportion of care partners may be in part-time or full-time employment [53], which raises complex issues around managing their work and care commitments and may diminish their time and energy to provide care. In addition, care partners may also be older adults themselves and have physical and mental health issues which may limit their capabilities to provide care [51]. As a consequence, care partners, particularly within dementia, may have increased negative feelings, depression, diminished well-being, and neglect their own

quality of life of people with PD and increase emotional stress [39].

cost saving implications for the health and social care system.

health [54]. Thus, they become 'the invisible or hidden patients' [52].

Caring and caregiving are considered to be different. Namely, caring is the affective component of 'one's commitment to the welfare of another', whereas caregiving is 'the behavioural expression of this commitment' ([50], p. 583). Likewise, caring has been described as the interplay between emotion and action involving endearing feelings such as love as well as activities involving labour [55]. Caregiving, however, has even been named as the 'unexpected career' due to the sudden onset of this role [56]. The shift into taking on care responsibilities may either be gradual or sudden, although in the case of neurodegenerative conditions such as PDD and DLB, this transition usually occurs gradually. The presenting symptoms of PDD and DLB may be so subtle that care partners may not notice a visible change in their

**38**

responsibilities, even though they may have started to help and support the care recipients. Thus, in early stages of the disease, care partners may not identify themselves as carers and may even dislike being called a 'carer' [57–59]. Instead, many people prefer to be acknowledged as a 'spouse', 'partner' or 'support person' [58], highlighting the importance of endorsing the relationship between the person receiving care and the person providing it.

The involvement of a care partner in the care of their family member is advantageous because they have a unique perspective on the care recipient's condition and thus, can provide a more precise and detailed description of their symptoms [60]. However, the State of Caring 2018 survey in the UK [48] found that 72% of care partners experienced worsening of their mental health and 61% in their physical health due to their caring role. Furthermore, over half of care partners anticipated that both physical and mental health would continue to deteriorate over the coming years, and a third of participants predicted that a decline in their mental and physical health would prevent them from being able to provide care to the care recipients in the future [48]. Brodaty and Donkin [52] contended that including care partners is so imperative that without their help, the quality of life of people with neurodegenerative conditions would drop so much that it would increase admissions to institutional care. However, this comes at the cost of care partners' own quality of life [52] and raises an important question about how to maintain the well-being of both partners when facing a neurodegenerative condition.

## **5. Theoretical models of dyadic care relationships in PD**

To understand the impact of PD factors on care partners and how they affect care partner well-being and the dyadic relationship, a theoretical framework is required. Such a framework also helps to understand the connections between the variables and to determine the direction of predictors. In the context of dementia, a number of multi-component models have been developed evaluating the factors contributing to caregiving-related stressors [61]. The most common care partner stress models in dementia [61] are:


These four preceding models take into account the characteristics of each member of the dyad as well as the care recipient's disease symptomatology and care partner's reactions and outcomes. In PD, the Stress Process Model [50] and the PD-specific Stress-Appraisal Model [65] are most applied by scholars. The Stress-Appraisal model [65] has been built on previous similar models [50, 66–69] and has since been developed further following a systematic review which evaluated burden, mental health and quality of life among care partners of people with PD [70]. The proposed adaptations by Greenwell and colleagues [70] are depicted in **Figure 1**.

The adapted PD-specific Stress-Appraisal model [70], which is derived from the Stress-Appraisal model by Goldsworthy and Knowles [65], captures care partners' experiences of care provision in PD (see **Figure 1**) and consists of four main domains [65, 70]:


The Stress-Appraisal model is useful in understanding the experiences of care partners in the context of PD and can appropriately be applied to PDD and DLB as well.

Although the Stress-Appraisal model is comprehensive, it does not incorporate the dyadic relationship as an important factor in the context of caregiving relationship. Townsend and Franks [71] proposed the *Binding Ties Theory*, which was designed to

#### **Figure 1.**

*The stress-appraisal model adapted from Greenwell et al. [70]. The dash line needs further examination. The dash boxes depict alterations to Goldsworthy and Knowles [65] model by Greenwell et al. [70].*

**41**

*Long-Term Partnerships in Lewy Body Dementias DOI: http://dx.doi.org/10.5772/intechopen.86204*

describe the quality of the relationship between adult children and their parents with cognitive impairment (see **Figure 2**). The authors considered the quality of the dyadic relationship to be crucial in care provision and an important determinant in the caregiving experience [71]. The model describes the associations between cognitive and functional impairment, closeness (positive), conflict (negative) and care partner well-being through measures of subjective caregiving stress, subjective caregiving effectiveness and depression. The findings suggest that negative ties were more predictive of care partner well-being than positive ties [71]. Furthermore, the pathway of 'cognitive decline relationship quality care partner well-being' was stronger than the 'functional decline relationship quality care partner well-being' pathway and advancing cognitive impairment led to less closeness and more conflict in the dyadic relationship [71]. This highlights that studies should evaluate both positive and

With regards to the intimate dyadic relationship in PDD and DLB, the Townsend and Franks' [71] model could be incorporated in the Stress-Appraisal model [65, 70] by considering 'cognitive and functional decline' as primary stressors, 'quality of the relationship' as a protective factor and 'care partner well-being' as an outcome.

A growing body of research spanning several decades has drawn attention to the impact that LBD has on care partners [70, 72]. The progressive and complex nature of the motor, psychiatric and cognitive symptoms of LBD [73] can reduce one's ability to carry out everyday activities and take care of oneself, thus increasing the need of a care partner. Care partners have a substantial role to play in the lives of people with PDD or DLB as they support and assist with activities of daily living, personal care, medication, feeding, housework, attending specialists' appointments, maintenance of the person's quality of life and independence, and being there as a partner and friend [51, 60, 74, 75]. Commonly, a care partner of a person with PD is a female spouse, aged around 70 years, living with her partner, having provided care for an average of 5 years and currently providing up to 16 hours of care per day [33, 76–79]. Although these descriptions are comparable to those providing care to someone with dementia, the care provision hours in dementia are notably lower

A recent qualitative meta-synthesis summarised the experiences of PD care partners into four interrelated themes describing (1) the need to carry on as usual, (2) the importance of support in facilitating coping, (3) the difficult balancing act between caregiving and caregiver needs, and (4) conflicts in seeking information and knowledge [80]. Thus, care provision within PD has been considered unique and complex in comparison to other neurodegenerative conditions but to date, little

is known about the profile of care partners of people with PDD or DLB.

negative interactions in the context of caregiving relationships.

**6. Care provision in LBD**

**Figure 2.**

*The binding ties theory [71].*

than in PD (i.e. 6–9 hours per day) [52].

*Long-Term Partnerships in Lewy Body Dementias DOI: http://dx.doi.org/10.5772/intechopen.86204*

**Figure 2.**

*Geriatric Medicine and Gerontology*

which require further investigation.

1.*Stressors*: care partner well-being is affected by the person with PD factors (= primary stressors), such as neuropsychiatric and cognitive symptoms, their quality of life, their ability to perform activities of daily living and functional dependency (but not motor symptoms), which decreases physical health and

increases depression in the care partner (= secondary stressors),

2.*Stress appraisals*: how care partners experience the disease can influence whether they make primary appraisals (i.e. seeing the disease as threatening and thus care partner becomes more involved in care provision by providing more hours of care) or 'secondary appraisals' (i.e. increase of burden and potentially developing coping strategies). Greenwell et al. [43] proposed that tertiary appraisals, which are affected by primary and secondary stressors, secondary appraisal and protective factors, also have a role in determining perceived burden and perceived uplifts by care partner, although burden was seen as a secondary appraisal in Goldsworthy and Knowles' [53] model.

3.*Protective factors (or mediators)*: an important predictor of burden is perceived social support, which can promote well-being or protect from negative consequences of stress. In Goldsworthy and Knowles' [53] model, quality of dyadic relationship, frequency of breaks, formal service hours as well as care partner self-esteem were important mediators in the process of care partner stress appraisal. Greenwell and colleagues [43] suggested that other predictors may include care partner personality traits, sense of coherence and self-efficacy,

4.*Outcomes*: the impact of primary and secondary stressors; primary, secondary and tertiary appraisals, and protective factors have a direct or indirect impact on care partner outcomes, such as determining their quality of life and depression.

The Stress-Appraisal model is useful in understanding the experiences of care partners in the context of PD and can appropriately be applied to PDD and DLB as

Although the Stress-Appraisal model is comprehensive, it does not incorporate the dyadic relationship as an important factor in the context of caregiving relationship. Townsend and Franks [71] proposed the *Binding Ties Theory*, which was designed to

*The stress-appraisal model adapted from Greenwell et al. [70]. The dash line needs further examination. The* 

*dash boxes depict alterations to Goldsworthy and Knowles [65] model by Greenwell et al. [70].*

**40**

**Figure 1.**

well.

*The binding ties theory [71].*

describe the quality of the relationship between adult children and their parents with cognitive impairment (see **Figure 2**). The authors considered the quality of the dyadic relationship to be crucial in care provision and an important determinant in the caregiving experience [71]. The model describes the associations between cognitive and functional impairment, closeness (positive), conflict (negative) and care partner well-being through measures of subjective caregiving stress, subjective caregiving effectiveness and depression. The findings suggest that negative ties were more predictive of care partner well-being than positive ties [71]. Furthermore, the pathway of 'cognitive decline relationship quality care partner well-being' was stronger than the 'functional decline relationship quality care partner well-being' pathway and advancing cognitive impairment led to less closeness and more conflict in the dyadic relationship [71]. This highlights that studies should evaluate both positive and negative interactions in the context of caregiving relationships.

With regards to the intimate dyadic relationship in PDD and DLB, the Townsend and Franks' [71] model could be incorporated in the Stress-Appraisal model [65, 70] by considering 'cognitive and functional decline' as primary stressors, 'quality of the relationship' as a protective factor and 'care partner well-being' as an outcome.

#### **6. Care provision in LBD**

A growing body of research spanning several decades has drawn attention to the impact that LBD has on care partners [70, 72]. The progressive and complex nature of the motor, psychiatric and cognitive symptoms of LBD [73] can reduce one's ability to carry out everyday activities and take care of oneself, thus increasing the need of a care partner. Care partners have a substantial role to play in the lives of people with PDD or DLB as they support and assist with activities of daily living, personal care, medication, feeding, housework, attending specialists' appointments, maintenance of the person's quality of life and independence, and being there as a partner and friend [51, 60, 74, 75]. Commonly, a care partner of a person with PD is a female spouse, aged around 70 years, living with her partner, having provided care for an average of 5 years and currently providing up to 16 hours of care per day [33, 76–79]. Although these descriptions are comparable to those providing care to someone with dementia, the care provision hours in dementia are notably lower than in PD (i.e. 6–9 hours per day) [52].

A recent qualitative meta-synthesis summarised the experiences of PD care partners into four interrelated themes describing (1) the need to carry on as usual, (2) the importance of support in facilitating coping, (3) the difficult balancing act between caregiving and caregiver needs, and (4) conflicts in seeking information and knowledge [80]. Thus, care provision within PD has been considered unique and complex in comparison to other neurodegenerative conditions but to date, little is known about the profile of care partners of people with PDD or DLB.

Studies have evaluated which aspects of PD (in the absence of cognitive impairment) have the highest impact on care partners. Findings suggest that both motor and non-motor symptoms of PD affect care partners' well-being, quality of life and burden but non-motor domains, particularly psychiatric manifestations such as apathy, psychosis, depression and cognitive impairment, tend to have a stronger effect [70, 72, 78, 81–85]. Similarly, the notion that caring for someone with mental illness is emotionally harder, more complex and taxing, as opposed to caring for someone with a physical illness, has been previously posited. This may be due to the changeable, unstable and erratic symptom presentation in mental health conditions, which disrupts 'the coherence of everyday life' ([86], p. 7). This is in line with literature on care partners of people with dementia [52, 87], PD [39, 70] and DLB [74], confirming the complexity of non-motor symptoms in PDD and DLB.

Providing care to a person with PD can be emotionally draining, physically challenging and mentally exhausting for care partners [75, 88]. The impact of PD on care partners is multifaceted, including social, financial, physical, emotional, mental and cognitive aspects. Socially, care partners of people with PD may not be able to go out as much as before, struggle to get away on holidays and have fewer social interactions with their friends, family and neighbours [74, 89–91]. In addition, due to care provision many care partners may be unable to do their usual daily tasks, activities and hobbies, and may receive insufficient social support from friends and family. Having hobbies, being socially active and receiving social support are important because they could protect against worsening of health and well-being [66, 70, 92]. Physically, care partners may experience deterioration in health [90], health-related quality of life [5, 93, 94] and greater fatigue [79].

In terms of mental–emotional aspects, care partners may encounter negative feelings, such as frustration, sadness, anger, resentment, guilt, worry [75, 95], and feel overwhelmed, stressed, strained and burdened [72, 74, 77, 78, 83, 84, 92, 96–98]. Care provision may significantly increase anxiety and depression [89, 93, 95] and lower care partners' mental health [93]. As a consequence, PD care partners' life satisfaction may reduce [95]. Furthermore, in non-PD care partners, the rates of mortality [98], cognitive impairment [99] and relationship dissatisfaction [100] may increase. All of these factors can be escalated with the progression of cognitive impairment in PD [101], which suggests that focusing on the care partners of people with LBD is crucial.

#### **6.1 Physical and mental health**

Several studies have found that care provision within PD can worsen mental health and result in distress in care partners [89, 93, 95] compared to the general population. Nearly 50% of care partners of people with PD may experience clinically significant anxiety and depression [72]. Among PD care partners, over a third experienced a deterioration of their health due to care provision [85]. Lack of sleep, fatigue, high blood pressure, muscle strain, headaches and gastrointestinal problems were also common in this group [77] and likely a direct result of providing care. Poor mental health in care partners is directly linked to duration of care provision in years and proportion of hours devoted to caring each day [79]. Moreover, lower levels of mental health are also predicted by care recipients' motor, psychiatric and cognitive symptoms, although drawing definite conclusions about what predicts mental health remains difficult due to the variability of the measures, inconsistent findings and lack of evidence [70]. Importantly, despite the care partners' own health needs, they felt they had to stay healthy as long as possible to be

**43**

*Long-Term Partnerships in Lewy Body Dementias DOI: http://dx.doi.org/10.5772/intechopen.86204*

in their role whilst taking care of themselves.

**6.2 Quality of life**

**6.3 Care burden**

apa0thy syndrome [112].

dimensions of burden [102, 114].

*6.3.1 What exactly is 'care burden': a dimensional perspective*

able to care for and support the care recipients [75, 92]. This presents major physical, financial, emotional, mental and social challenges for care partners to continue

Providing care to a person with PD can have a direct effect on care partners' well-being and quality of life. In the literature, quality of life has been synonymously used with other terms such as health, health status, perceived health, functional status, and health-related quality of life although these terms are independent of one another [102]. The concepts of quality of life are wide incorporating economic, environmental, cultural, social, spiritual and personal aspects [103, 104], whereas health-related quality of life specifically focuses on individual's physical, mental and social aspects and the perceptions of their global health [103, 104]. Health-related quality of life has been found to be lower among care partners of people with PD compared to general population [92] and decreases with the emergence and development of cognitive impairment in PD [5, 105, 106].

Quality of life is associated with several factors. Lower quality of life in care partners was predicted by the care recipients' disease-related factors (i.e. motor, cognitive and neuropsychiatric symptom severity, poorer quality of life, higher need for care, greater dependency in activities of daily living), personal aspects (i.e. higher age, depression) and care-related variables (i.e. longer duration of care provision in years and hours per day) [51, 70, 105, 107]. Well-being of care partners is important because lower strain and 'caregiving load' reduces the risk of institutionalising persons with PD [108], which has long-term implications for the future.

As PD progresses, the cognitive impairment advances leading to higher strain [83], burden [5, 76, 78, 106, 109] and stress [82] in care partners. The main contributors to care partner burden and stress in people with PDD were the person's neuropsychiatric symptoms (i.e. depression, psychotic symptoms) [78, 82] and cognitive decline [5, 76, 109, 110]. Apathy, a common and often under-recognised neuropsychiatric complication of PDD and DLB, is strongly associated with care burden [111], in part due to emotional blunting that is one of the dimensions of the

One of the most researched constructs in care partner research is 'caregiver burden' [49]. Several different definitions have been proposed but two interwoven descriptions from the 1980s are used concurrently to this day. George and Gwyther [113], p. 253, define burden as 'the physical, psychological or emotional, social, and financial problems that can be experienced by family members caring for impaired older adults'. The same year, Zarit et al. [87], p. 261, proposed a very similar explanation adding that burden is 'the extent to which caregivers perceive their emotional or physical health, social life, and financial status as suffering as a result of caring for their relative'. Even though both explanations encompass the multifaceted impact on care partners, the definitions of burden are still diverse, incoherent and vague in many research studies making measuring 'burden' ambiguous [102, 114]. The authors recommend that burden should be defined clearly, researched using mixed methods (i.e. both quantitatively and qualitatively) and evaluated as specific

able to care for and support the care recipients [75, 92]. This presents major physical, financial, emotional, mental and social challenges for care partners to continue in their role whilst taking care of themselves.
