through 1998. The ADRC collected data on the variables used in this analysis at entry and subsequent annual visits for as long as possible until the person with AD died or entered LTC. This design resulted in a variable number of data points per care recipient-caregiver dyad. The number of data points per dyad ranged from 1 to 10, with a mean of 2.5 per caregiver and 3.8 per care recipient. We used as many data points per person as were available to estimate rates of change for the independent variables except static demographic variables such as date of birth, gender, and race. During 1997 and 1998 the NEO Five Factor Inventory of personality (see below) was administered to as many of these caregivers as possible on a one-time basis. Of the sample of 332 caregivers, 58 had missing data on the personality instrument because they left the study before 1997 due to the death or LTC placement of the person with AD, 63 caregivers had missing data because they dropped out of the study prior to 1997, and 30 caregivers had missing data because they failed to return the NEO personality instrument, giving a total of 151 caregivers with missing NEO data. This left a sample of 181 caregivers with valid personality data. Although this sample is a subset of the samples used in two previous publications, (McClendon et al., 2006; McClendon et al., 2004) the personality data has not been previously used and has been introduced to clarify prior results. Measures Diagnosis of Alzheimer’s disease was based on NINCDS-ADRDA criteria (McKhann et al., 1984). Date of death. For 37% of the deaths in the sample with valid personality data, the date was determined as part of the ADRC’s procedures for arranging an autopsy following death. For
Because of our unexpected finding that neuroticism increased survival, it is important to attempt to replicate this finding in another study. It would also be valuable to administer the full 240-item NEO form to caregivers in order to use the measures of the six facets underlying neuroticism to test our hypotheses that it is the vulnerability facet of neuroticism that increases WIC and the anxiety facet of neuroticism that enhances survival. It is possible that one or more of the other facets (Angry Hostility, Depression, Self-Consciousness, Impulsiveness) may be related to survival instead of or in addition to vulnerability or anxiety. Ours is the first study to show a relationship between caregiver personality (i.e., neuroticism) and the survival of AD care-recipients. In the single previous study of caregiver personality and care-recipient survival, neuroticism (measured by Eysenck Personality Inventory) was not significantly related to survival (Brodaty et al., 1993). The difference between Brodaty and our study might be due to: The sample size used by Brody was 91 and thus provided less power than our sample (n = 180); Brodaty controlled for a caregiver training program but did not include measures of coping styles used by caregivers; other dimensions of personality were not controlled; neuroticism was tested with and without measures of change in dementia severity and nursing home admission whereas our analysis included changes in ADL and behavioral problem. Our analysis did not find neuroticism to be significant without WIC in the model. In sum, the main differences between Brodaty’s study and our study were sample size (91 vs. 180) and the measure of caregiver coping (training program intervention vs. measure of wishful coping). In our study, caregiver personality measurements were made on a one-time basis up to six years after the baseline measures. The varying lag times are not a problem if, as is often assumed, personality is relatively stable. However, there is evidence that small- to medium-sized changes in personality, including neuroticism, occur over the life course (Roberts, Walton, &