Using pupillometry to predict outcome in cognitive behavioral therapy for negative symptoms of schizophrenia.

BACKGROUND

Clinical trials of cognitive-behavioral therapy (CBT) for negative symptoms of schizophrenia have provided mixed results, perhaps because some patients are more likely to benefit than others. Patients likely to benefit may be those with greater pre-treatment motivation. To better examine the effects of motivation on treatment outcome, more objective measures of motivation are needed. Pupillary responses provide an objective biomarker of cognitive effort and motivation, with greater dilation associated with greater effort and motivation.

AIMS

The current study examined whether pre-treatment baseline pupil dilation predicted motivation and pleasure (MAP) negative symptom reduction in an open clinical trial of CBT for individuals with schizophrenia.

METHODS

Pupil dilation was recorded during the digit-span task at low (3 digits), moderate (6 digits) and high (9 digits) loads in participants with schizophrenia or schizoaffective disorder (N = 31) with persistent negative symptoms prior to delivery of mobile-assisted CBT for negative symptoms (mCBTn).

RESULTS

Greater pre-treatment pupil dilation during low, but not moderate or high, loads of the digit-span task significantly predicted greater reduction in MAP negative symptoms. However, while MAP negative symptoms improved throughout treatment, pupil dilation did not significantly change throughout treatment for any digit-span loads.

IMPLICATIONS

Pupil dilation may provide a much-needed prognostic biomarker of patients most likely to benefit from CBT for MAP symptoms, but did not change with change in MAP symptoms.