LIMITATIONS OF THIS STUDY

Methodological Issues

Firstly, it is important to consider the sample included in this study. The response rate of in this study was adequate (70.5%) and a variety of factors were associated with non participation. A minority o f participants who were identified as suitable for inclusion in the study, declined to take part because of experiencing recent life events. Therefore, it remains possible that people who chose to participate in this study had fewer life events than those who did not. Alternatively, those who declined due to recent stressful events may have been more likely to be depressed. Their inclusion in the study may have served to enhance the associations found.

Chapter Four: Discussion

causality being firmly established. There has been a good deal of uncertainty about the aetiological link between life events and depression in general and whilst this study has supported the association between the two in people with dementia but cannot confirm a direct causal relationship. Another factor which reduces the ability to confirm causality is that the onset o f depression in this sample was not dated. There are difficulties in dating depression in dementia sufferers, and it might be argued that depression may have been related to the incidence o f life events. By including only independent life events, those events which may have resulted firom either low mood or dementia were excluded firom analysis. Despite this, others have argued that factors such as background (Kahana, 1992, cited in Russo & Vitaliano, 1995) and personality (Poulton & Andrews, 1992, cited in Russo & Vitalino, 1995) may make an individual predisposed to life events. Events which were possibly dependent were excluded firom the analysis but some of these events may have been independent and their exclusion may have reduced the statistical power of the analysis.

Furthermore, this study did not consider the existence o f a history o f depression in either dementia sufferers or carers. It is likely that a previous history o f depression would have been a significant risk factor for the onset of later depression in either case and may have confounded the impact o f life events on depression to a degree. Furthermore, it may have been useful to collect information on the duration o f caregiving in order to see whether this had any association to depressive symptoms in carers.

Chapter Four: Discussion

The method o f eliciting life events used in this study was reliable, valid and has distinct advantages over checklist approaches. Nevertheless, some events may have been forgotten although this has not been reported in other studies (Orrell, 1994). Secondly, the dating o f life events may have biased in tiiat participants included events mistakenly in the 0-6 month period which may have overestimated the prevalence of life events.

There has be«i little research on the accuracy o f phenomenological, autobiographical and family history obtained from people with dementia. Ballard (1991) studied the concordance o f information between 92 dementia sufferers and their relatives. The level o f agreement between patient and carers responses was determined by comparing answers on the personal history section o f the CAMDEX interview. The overall percentage agreement was 76%, and the patients positive hit ratio (the percentage agreement for vsdiich the patient answered positive) was 93% but the relative’s positive hit ratio (the percentage agreement for all the questions which the relative answered positively) was 40%. This study concluded that positive responses made by dementia sufferers were more likely to be accurate but that negative responses were likely to be erroneous. Furthermore, the percentage agreement varied from 89% for past history to 44% for current mental functioning and there was no association between diagnosis or severity o f dementia and percentage agreement. This suggested that dementia sufferers tend to underreport information. As such the use o f prompting in the qualitative interview in this study may have helped to maximise recall. Partridge et al, (1990) have highlighted the need for appropriate information cueing in order to obtain the most

Chapter Four: Discussion

It is possible that this sample of dementia sufferers were not representative o f dementia sufferers overall. They were chosen from referrals to clinical services and all had a carer. Therefore it is not possible to generalise these findings to those dementia sufferers without such supports or those who are not in contact with services. The high level o f social support in this group may potentially account for the lack of significant findings in relationship to life events and depression. There may also have been a social desirability factor, i.e. dementia sufferers may have responded in such a way as to overemphasise their satisfaction with support.

It may have been useful to examine the type o f life events most associated with depression in dementia sufferers. Loss has been most widely associated with depression (Finlay-Jones & Brown, 1981), and studies with the elderly have reported both the incidence o f bereavement and poor health as most influential in differentiating depressed and non depressed groups (Prince et al, 1997). Murphy (1982) concluded that depression in the elderly is “closely associated with adversity; events involving loss or threat o f loss were implicated as in younger people”. In addition, pl^sical health was seen as an important provoking factor, perhaps through its perceived meaning for the individual of impending decline and death. The frequency o f reporting o f such events in this sample was high. It would be interesting to note if certain types o f loss events were particularly

Chapter Four: Discussion