There is, however, a more direct test of this hypothesis. In collabo -
ration with a BLSA physician, we examined the medical histories of
men and women on whom we had before-and-after personality mea -
sures (Costa, Metter, & McCrae, 1994). Initially , 153 volunteers were
considered healthy , 93 had a minor disease (e.g., treated hypertension),and 27 had a major disease (e.g., a history of cancer). Over time, 175volunteers stayed the same or improved in health whereas 98 had worsehealth status. These two groups did not differ in longitudinal changes inany of the five personality traits, and retest correlations were equallyhigh in both groups. Deterioration in physical health status was unre -
lated to change in personality in this group. It should be noted, how -
ever, that all of the subjects in this study were sufficiently well at the
second administration to complete a personality questionnaire. Moreserious illness might have affected personality scores.
In 1991, Siegler and colleagues offered the first clear evidence of
personality change associated with disease. They asked caregivers ofmildly to moderately demented patients to rate the patient’s personalityas it had been before onset of the disease (chiefly Alzheimer’s) and as itwas now. They used the same version of the NEO-PI that we had admin-istered to spouses and peers of BLSA participants. Dramatic effects wereseen. Prior to their illness, the patients had not differed from the generalpopulation. But subsequently they showed increased Neuroticism, espe-cially Vulnerability , decreased Extraversion, and a precipitous decline inConscientiousness. Planning, organization, and self-discipline appear tobe dramatically impaired by dementing disorders.
This finding has been widely replicated (Chatterjee, Strauss Smyth,
& Whitehouse, 1992; Siegler, Dawson, & Welsh, 1994; Welleford,Harkins, & Taylor, 1995), and it has been extended by Trobst (1999) toa different category of neurological patients, those with long-term con -
sequences of tramautic brain injury (chiefly from automobile acci -
dents). Patients with Parkinson’s disease show some of the same
changes (Mendelsohn, Dakof, & Skaff, 1995).
Taken together, these two lines of research make a clear contrast.
Diseases of the heart, or liver, or lungs may have substantial effects onpeople’s lives, but they do not have permanent effects on personalitytraits. Diseases of the brain, however, often do. This deep and selectivetie of personality traits to the brain is a point to keep in mind when, in alater chapter, we turn to a theoretical account of personality itself.
It also provides a new perspective on a phenomenon noted many132 PERSONALITY IN ADULTHOOD