A controlled single case study with repeated fMRI measurements during the treatment of a patient with obsessive-compulsive disorder: testing the nonlinear dynamics approach to psychotherapy.

There is increasing evidence that obsessive-compulsive disorder (OCD) is associated with a dysfunction of cortico-striato-thalamo-cortical neuronal circuits. In order to examine treatment-related changes in neuronal processes, a drug-naive female patient with OCD (subtype: washing/contamination fear) and an age- and gender-matched healthy control were repeatedly tested using functional magnetic resonance imaging (MRI) during the presentation of a symptom provocation task. Patient-specific visual stimuli of symptom provoking situations were compared with disgust provoking and neutral pictures. FMRI scanning was conducted at the beginning, during and upon completion of an inpatient treatment. During the treatment period of more than eight weeks (combined behavioural and systemic couple therapy) the patient filled out a therapy process questionnaire (TPQ) which was administered daily. Results show a phase transition-like change characterized by a sudden reduction of clinical symptoms as assessed by the Yale-Brown Obsessive Compulsive Scale (Y-BOCS) in the middle of the treatment period. Before the discontinuous symptom reduction occurred, the dynamic complexity of the TPQ-time series increased which might be indicative for a critical instability of the system. The fMRI results at the beginning of the treatment suggest strong activities in various brain regions, especially in the anterior cingulate cortex. The results of the second and third acquisition revealed comparably smaller OCD-related neuronal responses. The results may indicate that important clinical changes are taking place during the psychotherapy process which correspond to changing patterns of brain activation as well as to critical instabilities and phase-transition like phenomena in the time-series of the patient's daily self-report data.