Diathesis 173variability in the course of the illness. Studies of clinic sam-
ples of individuals with FM have demonstrated continued
presence of symptoms for most patients 10 years after
symptom onset (Kennedy & Felson, 1996; Wigers, 1996).
However, other investigators using community samples
have uncovered better recovery rates. For example, in a
community-based, longitudinal study of individuals with
chronic widespread pain, 35% still had widespread pain, 50%
had regional pain, and 15% had no pain at a two-year follow-
up, suggesting improvement in 65% of the sample (MacFar-
lane et al., 1996). Those with FM who do not recover tend to
be older, have less education, and have more symptoms for a
longer period of time.
As in RA and OA, women are at particular risk for devel-
oping FM. Approximately 85% of FM patients are women
(Lawrence et al., 1998). Furthermore, the prevalence of FM
increases with age, and in many cases is secondary to other
chronic pain conditions, such as OA, which occur most fre-
quently among older adults (Lawrence et al., 1998).
Despite the lack of de“nitive pathology in FM, investiga-
tors have attempted to identify the role of genetic in”uences
in FM. Speci“cally, researchers have hypothesized that if FM
is indeed a disorder of neurohormone or pain-transmission
dysregulation, there may exist a genetic vulnerability for this
dysregulation (Clauw & Chrousos, 1997). Consistent with
this hypothesis, there is evidence of familial predisposition
to FM (Pellegrino, Waylonis, & Sommer, 1989; Stormorken
& Brosstad, 1992). Furthermore, results of a recent study
demonstrated that individuals with FM were more likely to
have a speci“c genotype of the serotonin-transporter gene
than healthy individuals (Offenbacher et al., 1999). In
addition, among individuals with FM, those who had this
genotype displayed greater amounts psychological distress
than those without this genotype (Offenbacher et al., 1999).
These results are underscored by the fact that serotonin regu-
lates mood, sleep, and pain, which are disturbed in FM
(Schwarz et al., 1999). Although preliminary, collectively
these results suggest that genetics may play a role in the de-
velopment of FM.
Psychological Diathesis Factors
Biological factors play a prominent role as diatheses for pain
and disability in musculoskeletal conditions. We next turn
our attention to the psychological sources of vulnerability
and resilience that may affect adjustment to these conditions.
Among the psychological features that have been the focus of
empirical research are factors such as neuroticism, low self-
ef“cacy, locus of control, depression, somatization, and low
levels of positive affect.
NeuroticismPersonality has long been thought to play a role in the
development of and adaptation to a host of chronic illnesses,
including arthritis-related conditions (Af”eck, Tennen, Ur-
rows, & Higgins, 1992). Early empirical work aimed at de-
termining whether certain personality attributes were more
prevalent among individuals with particular medical disor-
ders relative to other groups. In contrast, more recent re-
search has focused on identifying individual differences in
personality within diagnostic groups that contribute to dis-
ease course. One personality characteristic that has particular
relevance for a biopsychosocial understanding of adaptation
among those with chronic pain is neuroticism, or the disposi-
tional tendency to experience negative emotions. Because in-
dividuals high in neuroticism report an increased frequency
of stressful experiences (Bolger & Schilling, 1991), and be-
cause the experience of stress may enhance disease activity
and symptoms of chronic pain (Zautra, Burleson, Matt, Roth,
& Borrows, 1994), neuroticism may be especially problem-
atic for those with a musculoskeletal condition. In fact,
among individuals with RA, neuroticism has been associated
with poor self-rated functional status (Radanov, Schwarz, &
Frost, 1997), more intense pain (Af”eck et al., 1992), and
mental health problems (Fyrand, Wichstrom, Moum, Glen-
nas, & Kvien, 1997). A neurotic disposition is also likely to
play a role in adaptation to OA and FM, and although few
studies have investigated it, the available data do point to this
possibility. For instance, patients with FM who score high in
neuroticism are more frustrated with their physicians than
those low in neuroticism (Walker et al., 1997). Moreover, in
one of the few studies investigating the role of neuroticism
in adaptation to OA, neuroticism at baseline predicted pain
up to 20 years later (Turk-Charles, Gatz, Pedersen, &
Dahlberg, 1999). The existing data suggest that identifying
subsets of pain patients with certain personality attributes,
particularly neuroticism, may enhance our accuracy in the
prediction of clinical outcomes in chronic pain.Self-Efficacy and ControlOne of the most well-researched individual difference vari-
ables in health psychology is that of self-ef“cacy or, a related
concept, locus of control. Both concepts refer to an individ-
ual•s belief in being capable of achieving desired goals.
Research over many years has shown that having such a be-
lief system is strongly related to health maintenance and re-
covery from health stressors. Certainly, chronic illnesses such
as arthritis and FM are major challenges to freedom of action
and general well-being. Thus, developing and enhancing a