CT Compared With ERP
Four studies that used the Y-BOCS have compared CT with
variations of ERP. van Oppen and others randomly assigned
patients to either 16 sessions of CT or 16 sessions of selfcontrolled
ERP (all exposure was conducted by the patient
without therapist supervision) (29). Both treatments led to an
improvement in OCD symptoms, although CT was more
effective than ERP (Y-BOCS reductions were 53% and 43%,
respectively). Importantly, the brief and infrequent therapist
contact (weekly 45-minute sessions), along with reliance on
patients to manage all exposure practice on their own, likely
accounted for the relatively modest effects of ERP in this
study. Moreover, CT involved behavioural experiments that
resembled exposure, which blurred the distinction between
the 2 treatments. Only after behavioural experiments were
introduced (at the sixth session) did symptom reduction in the
CT group approach that of ERP. Thus it is possible that the
exposure component of behavioural experiments is key to the
efficacy of CT. Using a sample that overlapped with the van
Oppen and others study, van Balkom and others found no significant
difference between CT with behavioural experiments
and self-controlled ERP