Sensorimotor gating and clinical outcome following cognitive behaviour therapy for psychosis

Prepulse inhibition (PPI) of the startle response refers to the ability of a weak prestimulus to transiently inhibit the response to a closely following strong sensory stimulus. PPI provides an operational index of sensorimotor gating and is reduced, on average, in people with schizophrenia, relative to healthy people. Given the variable response to Cognitive Behaviour Therapy for psychosis (CBTp) and positive associations between pre-therapy brain and cognitive functions and CBT outcome across disorders, we examined whether pre-therapy level of PPI is associated with clinical outcome following CBTp.

Fifty-six outpatients stable on medication with at least one distressing symptom of schizophrenia and willing to receive CBTp in addition to their usual treatment were assessed on acoustic PPI. Subsequently, 28 patients received CBTp (CBTp+treatment-as-usual, 23 completers) for 6-8months and 28 continued with their treatment-as-usual (TAU-alone, 17 completers). Symptoms were assessed (blindly) at entry and follow-up.

The CBTp+TAU and TAU-alone groups did not differ demographically, clinically or in PPI at baseline. The CBTp+TAU group showed improved symptoms relative to the TAU-alone group, which showed no change, at follow-up. Pre-therapy PPI level correlated positively with post-CBTp symptom improvement.

Relatively intact sensorimotor gating is associated with a good clinical response following a 6-8months course of NICE compliant CBTp in schizophrenia. Pharmacological or psychological interventions capable of improving PPI may enhance the effectiveness of CBTp in people with schizophrenia, particularly in those who fail to show clinical improvement with currently available antipsychotic drugs and adjunctive CBTp.