The frequency of BPSD among patients with dementia in this study indicated that irritability was the most frequent type of BPSD exhibited by PWD (84.2%), followed by apathy (80.7%) and agitation (77.2%) as reported by caregivers (Table 2). Caregivers also implied that the least reported types of BPSD were elation (32.7%), followed by motor disturbance (57.5%) and appetite (59.4%)(Table 2). A previous study conducted in Malaysia showed that apathy was the most prevalent (83.2%), followed by agitation (60%) and sleep disturbance (53.8%) . Past studies have concluded that neuropsychiatric symptoms in PWD are heterogeneous and essentially unpredictable in the presentation of emotional experience, thought content, perception and motor function which may explain the vast findings of research on prevalence of BPSD. However, despite the general discrepancy, there has been previous research where similar findings can be reported such as a study conducted by Mukherjee et al.  which highlighted that apathy/indifference was the most frequent (72.9%), followed by agitation/aggression (68.2%), and irritability/lability (59.8%). Aberrant motor behavior (31.8%), delusions (29%), and hallucinations (23.4%) were less frequent, while disinhibition (13.1%) and elation/euphoria (9.3%) were rare.
The pattern of previous findings is almost similar to the current research in which the three most frequent types of BPSD were reported accordingly while the least frequent types of BPSD were also highlighted in similar pattern with motor disturbance and elation being one of the least frequently reported BPSD. However, the results from other studies were inconsistent depending on different types of BPSD, the number of BPSD studied, environmental parameters and instrument used [5, 6, 17, 50, 51].
The pattern in which apathy is found to be one of the most common type of BPSD across several studies could be due to the presentation of the syndrome with reduced initiation and motivation, decreased social engagement, emotional indifference that could be misidentified with depression. PWD is rarely able to express pathological feelings of sadness, unhappiness, and preoccupation with depressing topics, hopeless (strongly associated with suicidal ideation) and loss of self-esteem . As dementia progresses, other BPSD may predominate. Increased cognitive impairment was associated with more activity disturbances, hallucinations, agitation and sleep disturbances; however, delusions, affective disturbances, anxieties and phobias improved with worsening of the cognitive status . Psychosis occurred more frequently with declining cognition and anxiety; depression were more common in younger patients .
In this study, the context of caregiving is primarily within vicinity of home-based settings which means that caregivers have more time providing care to PWD compared to when they are being institutionalized or sent to nursing home where most of past research have been focused on, thus, differences in reports as they varied in duration of their observation and presentation.
Table 3 indicated that Total BPSD severity score was significantly correlated with Total Caregiver Burden (r = .199, p < .01) which imply that the higher the severity of BPSD, the higher the level of caregiver burden. Of all the types of BPSD, delusion, agitation, irritability and nighttime behavior, hallucination, depression, apathy, disinhibition and motor disturbance were significantly correlated to total caregiver burden except for anxiety, elation and appetite.
Behavioral and psychological symptoms of dementia (BPSD) are very common and are significant symptoms of the illness, contributing most to caregiver burden and often resulting in premature institutionalization of the person with dementia. According to International Psychogeriatric Association , among the most intrusive and difficult BPSD types to cope comprise of delusions, hallucinations, depression, and anxiety. Past studies have indicated similar findings in which delusion and agitation were significantly associated with caregiver burden; thus, treatments for such BPSD may reduce the associated burden .
Delusions were seen in 14% of patients, were often seen early in the course of the disease, and were prominent and persistent. The presentation of delusion could instigate subsequent negative reactions by PWD that can be manifested in physical forms as a reciprocal response to caregivers. This is supported by studies that suggested that delusions are a risk factor for physical aggression. A study by Deutsch et al.  found that 43.5% of patients with a diagnosis of probable AD had delusions. Gilley et al.  also reported that the presence of delusions predicts the occurrence and frequency of physical aggression, with 80% of study participants who showed high rates of physical aggression (i.e. more than one episode per month) also having delusions. Symptoms like delusional thinking, activity disturbances and aggressiveness were more likely than other symptoms to be rated as troublesome to the caregiver.
Agitation has been found to correlate strongly with irritability, disinhibition, and delusions. Agitation and aggression are among the most troublesome BPSD symptoms for caregivers and, along with depression and psychosis, are leading predictors of institutionalization . Sundowning is the occurrence and exacerbation of BPSD in the afternoon or evening. Agitation and sleep disturbances commonly accompany sundowning which increases the burden of care on caregivers, as it often occurs when the family members are at the lowest level.
In addition to psychotic symptoms and physical aggression, mood disturbance and disinhibition can also contribute greatly to caregiver burden. Current finding shows that depression (r = .157), apathy (r = .379) and disinhibition (r = .201) correlate significantly with caregiver burden. Depression may be especially challenging for caregivers to handle not only because of the difficulty it causes caregivers in dealing with the patients but also because of the negative impact it has on the patient’s quality of life. Anger/aggression (26%) and depression (17%) were the most frequently cited patient symptoms having impact on caregiver burden. Shaji et al.  reported that delusions, activity disturbances and aggression were perceived by caregivers to be more troublesome at times than memory deficits.
Current findings reported that there were a number of types of BPSD that were not significantly correlated to total caregiver burden which comprised of anxiety, elation and appetite. This could be explained by the fact that BPSD symptoms such as appetite is deemed less intrusive compared to delusion and agitation which includes physical violence. They cannot be easily dismissed by caregivers as they make them distressed, hence increase on caregiving burden. Disruptive behaviors are more disturbing partly because of the adverse impact on the emotional connection between the caregiver and the care-recipient and partly because they exacerbate difficulties in other domains (e.g., caring for activities of daily living) .
Although disinhibition (61.4%) and motor disturbance (57.5%) were found to be one of the least frequently reported type of BPSD, the presentation of respective symptoms has been shown to have strong correlation with caregiver burden which could mean that the influence of BPSD on caregiver burden is not directly related to how common or frequently the symptoms are but more of the underlying experiences of caregiving from the respective BPSD. Thus, it is to be underscored that the burden associated with BPSD is different for each symptom and does not always depend on frequency and severity of BPSD but could be extended to the nature of BPSD. These findings suggest that some symptoms, such as agitation/aggression and irritability/lability, as well as disinhibition and motor disturbance may affect the caregivers significantly, although their frequency and severity are low .
Mediating effect of coping strategies and personality styles
Results reported conclude that majority of subscales in coping strategies mediate the relationships between BPSD and caregiver burden. Of coping strategies, self-distraction, active coping, planning and acceptance were found to mediate the relation between BPSD and caregiver burden whereas for personality styles, conscientiousness was the only subscale found to mediate the relationship. However, the mediation of endorsed coping strategies and personality style were all found to have partial mediation effect to the relationship.
In general, a given variable may be said to function as a mediator to the extent that it accounts for the relation between the predictor and the criterion. Mediators explain how external physical events take on internal psychological significance. The research model used in this study diagrams the mediating process by which the stressor precedes and influences the mediator and therefore affects the outcome .
The Multidimensional Stress-Process Model (SPM) posited how multiple stress factors contribute to negative outcomes for caregivers which was categorized into four types of variables that affect the well-being of caregivers: contextual variables, primary objective stressors, secondary stressors, and modulating variables. Based on the model, the most prominent primary stressors investigated are BPSD whereas coping strategies have a modulating function of different individual responses to the same care situation . In a recent study that investigated the model also found that personality is one of the internal mediators to the relationship between primary stressor and outcome ; however, there has been lack of studies that have looked into the personality traits that have mediation effect in relation to BPSD and caregiving.
In the current research, it was reported that most coping strategies were found to mediate the relationship between BPSD and caregiver burden. This is supported by Lazarus  who argues that coping is a powerful mediator of the emotional outcome resulting from a stressful environmental transaction. Studies conducted by Folkman and Lazarus  highlighted that emotional state of the individual during the stressful encounter changed either positively or negatively based upon the type of coping strategy that was used. Although current research is not investigating on the direction of association of specific coping strategies and personality style; however, it does reveal that with the inclusion of self-distraction, active coping, planning and acceptance as well as personality characteristic of conscientiousness, they signified to be partially accounted for the relationship between BPSD and caregiver burden.
According to Lazarus and Folkman , there is no clear guidelines on whether coping effort is deemed successful but instead is more dependent upon the caregivers’ appraisal if the transaction with the environment was adequately resolved. This judgment is made based on the individual’s personality characteristics, values, beliefs, and expectations related to the different factors involved in the encounter. Coping process and strategies selected are not inherently good or bad.
Based on the current findings, it reveals that most of the highlighted mediators are problem-focused strategies which include defining the problem, generating alternative solutions, weighing the alternatives in terms of their costs and benefits, choosing among them, and acting . Problem-focused coping is used when the individual makes a change with his/her relationship with the perceived stressor, such as working to fix a discrepancy between one’s current situation and what one wants. This is supported by a study conducted by Borden  which indicated that problem-focused coping directly contributed to caregivers having positive focus and therefore mediating psychological well-being.
This may suggest that strategies that are more emphasized on resolving stressor, which in this case is BPSD, influence the interaction with outcome. This is supported by Essex, Seltzer and Krauss  who found that greater use of problem-focused coping strategies and less use of emotion-focused coping techniques buffered the negative impact of stress on caregivers’ well-being. Similarly, in a study conducted by Miller et al. , it revealed that emotion-focused coping was significantly related to increased psychological distress in caregivers whereas use of problem-focused coping was tied to decreased distress. However, given that Williamson and Schulz  found emotion-focused coping more effective and problem-focused coping ineffective for AD caregivers indicates that coping style requires further study. This brief review of the literature demonstrates that the AD studies examining mediating models are at best inconsistent, and at times conflicting.
There is indeed increasing evidence that individual differences in personality may affect how carers experience and respond to the caregiving role. This is supported by Kobasa and Puccetti  who stated that personal characteristics affect health outcomes through coping strategies. Personality characteristics affect the processes that individuals use to appraise stressful events and predispose them to cope in certain ways when they confront these events .
Previous studies have noted that personality variables are consistently associated and predictive of a range of outcomes in dementia carers and that they are of important predictive value in terms of outcomes for people with dementia. Results in the current finding indicated that out of all the five-taxonomy personality traits, conscientiousness was found to have partial mediation effect on the relationship between BPSD and caregiver burden.
This can be explained by the fact individuals who score high on this trait are self-disciplined and organized, which is linked to greater health-promoting behaviors which would result in better subjective and objective health . Highly conscientious individuals also report a sense of competence and confidence, and this may partially account for their apparently better mental health . Thus, due to the nature of the personality, it provides a strong proclivity for caregivers to process the stress and implement strategies that are effective in reducing the stressor which in return would lessen the caregiver burden.
According to the results, it can be seen that there is a pattern between the mediator coping strategies that are more problem-focused which share similar characteristics as being conscientiousness whereby both factors consistently emphasize on organization, efficiency, orderly and structure. The shared components are based on managing the intensity and complexity of primary stressor which would in turn influence the level of caregiver burden. Although there is no significance in association between being conscientiousness and the endorsed coping strategies to show how personality trait is a predisposition to coping responses; however, the shared similarities may provide substantial interpretation on the relationship between BPSD and the outcome of caregiver burden which can be explained through responses and characteristics that are systematic, organized and planned.
Thus, this imply that caregiver burden is not so much from the frequency of the behavior, but it could be based on the nature of the types BPSD that are appraised by caregivers who manage these PWD at home.
There were few limitations in this study. Firstly, the lack of consideration of the duration of caregiving and how it may play a role in the burden of care. Longer duration of caregiving and more experienced caregivers may not feel much caregiver burden if they have acquired suitable coping strategies that have been effective in managing their stress level over time. Secondly, there is lack of specificity on different stages of dementia and how it can influence of emergence of BPSD. Caregivers of PWD were not provided with specific details of severity levels unless requested. Thus with the limited information of severity level of dementia, the presentation of BPSD is not exclusively delineated according to according to the presentation of the disease but more of how BPSD in general is associated with caregiver burden.
Future research should take into consideration the information on PWD’s disease progression to get a more refined understanding on presentation of BPSD to the outcome of caregiver burden. Future studies also should look into the mediating role of personality styles that can explain the relationship between stressor and caregiver burden.
The study provides implication on a fundamental understanding that the frequency of BPSD is not necessarily associated with caregivers’ burden level but more into the nature of the BPSD. Based on the association of BPSD to caregiver burden, it provides inferences that delusion, agitation, irritability and nighttime behavior are among the main behaviors to intervene on PWD first as they demonstrated to be highly correlated to caregivers’ burden level. Another implication of the study is to prevent caregiver burnout by suggesting that it is crucial to increase coping skills that are more problem-focused and action-oriented that share components of being systematic, thorough and organized as they have shown to mediate the relationship to the outcome.