Obsessive– Compulsive Disorder 485
that is primarily behavioral with only a slight emphasis on cognitive processes, cognitive
therapy as treatment that consists mainly of cognitive restructuring with no formal ERP,
and CBT as treatment with a fairly equal emphasis on ERP and cognitive restructuring.
It is now well established that ERP is an effective treatment for OCD (e.g., Foa,
Liebowitz, et al., 2005; Marks, Hodgson, & Rachman, 1975; Rachman et al., 1979)
and that it is effective when offered on an outpatient fee-for- service basis (Franklin,
Abramowitz, Kozak, Levitt, & Foa, 2000) or when offered to ethnic minority patients
(Friedman et al., 2003). In their review of 12 outcome studies involving 330 patients
with OCD, Foa and Kozak (1996) concluded that 83% of patients were improved with
ERP. Several meta- analytic studies have concluded that ERP is associated with large
pre–post treatment effect sizes (Abramowitz, 1996; Abramowitz, Franklin, & Foa,
2002; Eddy, Dutra, Bradley, & Westen, 2004; Kobak, Greist, Jefferson, Katzelnick, &
Henk, 1998; van Balkom et al., 1994) and average symptom reduction ranges from 48
to 59% (see Kozak & Coles, 2005). Percentage of patients who reach recovery at post-
treatment ranges from 24 to 73% with recovery defined as 25–50% symptom reduction
(Eddy et al., 2004; Fisher & Wells, 2005). However, if stricter criteria are utilized, less
than 30% of patients are asymptomatic at posttreatment (Fisher & Wells, 2005).
ERP has been shown to be significantly more effective than medication alone
(Foa, Liebowitz, et al., 2005), although other studies have found equivalent treatment
effects (van Balkom et al., 1998; see comparison review by Christensen, Hadzi- Pavlovic,
Andrews, & Mattick, 1987) or a possible advantage of combined ERP and SRI medica-
tion (Cottraux et al., 1990; Hohagen et al., 1998). In their meta- analytic study Eddy
et al. (2004) reported greater effect sizes for ERP or cognitive therapy than medication
alone but the highest effect sizes were found for the combined pharmacotherapy and
psychotherapy conditions. Although only a few studies report long-term follow-ups, Foa
and Kozak (1996) concluded that 76% of patients maintain their treatment gains for
an average 29 months. However, a significant number of individuals with OCD (37%)
either refuse ERP, drop out of therapy, or fail to respond (Stanley & Turner, 1995), and
only a minority of treatment completers are entirely symptom-free at posttreatment
(e.g., Fisher & Wells, 2005). Also, some OCD subtypes may not respond as well to ERP
such as individuals with pure obsessions, hoarding, or mental contaminations (Rach-
man, 2003, 2006; Steketee & Frost, 2007). Thus despite the documented efficacy of
ERP, there is still considerable room for improvement.
Recent OCD treatment outcome studies of CBT that place an equal weight on cog-
nitive interventions and ERP are more relevant to the cognitive therapy described in this
chapter. Although these studies are fewer in number, the initial results are most encour-
aging with CBT showing strong treatment effects (e.g., Franklin, Abramowitz, Bux,
Zoellner, & Feeny, 2002; Freeston et al., 1997; O’Connor, Aardema, Bouthillier, et al.,
2005; McLean et al., 2001; van Oppen, de Haan, et al., 1995; Whittal et al., 2005).
Moreover, patients who show a good response to CBT also experience a significant
improvement in their quality of life that extends beyond reductions in OCD symptoms
(Diefenbach, Abramowitz, Norberg, & Tolin, 2007; Norberg, Calamari, Cohen, & Rie-
mann, 2007). However, a critical question is whether adding cognitive interventions to
ERP improves treatment over a strictly behavioral approach to treatment. The findings
from these comparison studies are far from clear. Some have found that CBT (cogni-
tive therapy plus ERP) is equivalent to ERP alone (O’Connor, Aardema, Bouthillier, et
al., 2005; Whittal et al., 2005), whereas others suggest that more intensive ERP alone
might be most effective (McLean et al., 2001) and at least one study reported superiority