ESCALA LOCAL

According to the Five factor model of personality, analysis of inventories covering the full range of personality traits will result in five different factors. It would be reasonable to expect DAT to produce changes specific to these five factors. However, this was not the case. In the current study, a three factor solution was chosen as appropriate after examining the scree plot and testing the stability of the factors. As the first factor accounted for 33% of the variance it would also have been valid to chose a single factor solution. Such a large first factor is indicative of a global personality change across the five factors. In a recent study by myself and colleagues, personality changes in an elderly community sample were examined using the personality changes included in the DSM-III-R and ICD-10 criteria for dementia (Jacomb et. al., 1994, see Appendix 6.1). Factor analysis of this data showed that the first factor accounted for 26% of the variance with the next factor dropping to 9%. The sample used in this study included a large majority of normal, elderly people for whom no personality changes were reported. Of those who were reported to show some personality change, most only showed change in a few items. There was not considered to be enough variability within this group to be able to identify different patterns of change and so a single factor solution was considered appropriate. In the

current study the majority of the sample were demented and informants reported considerable personality change. It was therefore considered that there was enough variability in this sample to be able to determine different patterns of change.

Three scales were constructed from the three rotated factors. Scale 1 contains clusters from the positive poles of each of the five factors described in the five-factor model of personality. The second scale, Scale 2, is composed of clusters from the Agreeableness factor of personality as well as the negative pole of Neuroticism. Scale 3 is composed of clusters from the negative poles of Extroversion, Conscientiousness and Openness. It would be expected that the clusters from the negative poles would have loaded negatively on the first factor. This was in fact the case, but the degree of factor loading was relatively low and so these clusters were not included in Scale 1. Scale 3 was, however, significantly negatively correlated to Scale 1.

Some other studies have earned out factor analyses on instruments assessing personality or behaviour changes in dementia. It is very difficult to compare such studies as the different factors which are obtained will depend to a great extent on the range of items entered into the analysis. One of the strengths of the current study was the use as a sampling frame, of a personality inventory covering the full range of personality traits found in the normal population. Following the rating of a scale based on Goldberg's complete inventory by clinicians, the instrument was reduced to a more manageable size while still containing all those personality traits seen as changing in DAT. A weakness of many other studies is that they have used instruments which are based on clinical reports of change or carer reports of problem behaviours. Obviously, such scales can only detect relationships between a small range of variables. Factor analysis of the data collected in this study enables us to examine the relationship between traits across the full spectrum of personality.

Despite the difficulties in making such comparisons, these studies will be briefly compared to the current study. Sultzer et al. (1992) carried out a principal components analysis on the results obtained from the completion of the Neurobehavioural Rating Scale on 83 patients with dementia. This gave a six factor solution with cognition loading on a separate factor to those characteristics which were similar to those in Scale 2. No measures of exü*oversion or apathy were included in Sultzer's study. In a study by Greene et al. (1982), factor analysis was carried out on a scale designed to measure behavioural and mood disturbance and three factors emerged. The first factor was similar to Scale 3 and included passive behaviours plus some memory items, the second factor included agitated, restless

behaviour and some memory items while the third factor contained items measuring irritability and moodiness. This last factor, which is similar to Scale 2, was not associated with the memory items. The results found in Greene et al.'s study for the first and third factors are similar to that found in the current study. The study by Greene et al., however, had 34 variables and only 38 subjects, so the results may not be stable or reliable.

Gustafson (1975) carried out a factor analysis on a large range of items including memory, behaviour and psychiatric problems, which he had assessed in 57 patients with pre-senile dementia. Again, the ratio of variables to cases was only about 1:1. Fourteen factors were reported, with most of the items which are comparable to the current study loading on different factors. Irritability and obstinacy did, however, load on the same factor.

Recently, Jorm et al. (1993) carried out a principal components analysis on a range of clinical variables from a community sample of elderly people in Sweden. The first factor, which included a range of cognitive items, also included apathy and quietness, while the second factor included many of the traits covered in the current study. This second factor did include some measures of memory loss. Overall and Beller (1984) factor analysed the Brief Psychiauic Rating Scale and found separate factors for anxiety/depressed mood as well as another factor measuring hostility, suspiciousness and uncooperativeness.

Two studies have performed factor analysis on results obtained from demented subjects using the Blessed Dementia Scale. Stem et al. (1990) found four factors, two of which contained personality items. One factor included items similar to those found in Scale 2, while the other factor contained items assessing apathy or withdrawal. Rubin et al. (1987a) analysed 17 items based on 44 subjects and isolated seven factors. However, they then grouped these factors into 'four clinically meaningful groups'. These were passive behaviours, agitated behaviours, including irritable, self-centred behaviours and suspiciousness. As with the study by Stem et al., passive behaviours including apathy fell into a separate factor from the more 'disagreeable' characteristics.

In all of the studies discussed here, items measuring the negative pole of Extroversion (apathy, withdrawal, lack of initiative), load in different factors to items which fall into the Agreeableness factor of personality such as irritability, obstinacy. This is what was found in the current study.