Abnormal intrinsic brain activity of the sensory-motor area as a predictor of the response to selective serotonin reuptake inhibitors in treatment-naïve obsessive-compulsive disorder.

OBJECTIVES

Obsessive-compulsive disorder (OCD) is a highly prevalent and chronic neuropsychiatric disorder. Selective serotonin reuptake inhibitors (SSRI) are first-line pharmacological agents for treating OCD. However, nearly half of patients show insufficient responses to SSRI. The aim of the study is to assess the relationship between the intrinsic brain activity and SSRI response by using the z-standardized fractional amplitude of low-frequency fluctuations (zfALFF).

METHODS

We exacted the zfALFF to probe the brain activity patterns from resting-state functional magnetic resonance imaging (fMRI) data in 63 treatment-naïve OCD patients (classified into 31 responders and 32 nonresponders based on the percentage of improvement in symptoms) and 33 healthy controls (HC). Then, the zfALFF values of large-scale networks and each brain region were compared among the three groups. The zfALFF values demonstrating significant intergroup differences were utilized to investigate characteristic neuroimaging changes in OCD, and factors predicting SSRI response.

RESULTS

In contrast to HC, OCD exhibited significantly lower zfALFF in sensory-motor area (SMA), and the brain regions within this network, including the bilateral postcentral gyrus (PoCG.L and POCG.R) and the left paracentral lobule (PCL.L). Although the alteration of zfALFF was not related to pre-treatment scores of the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), the lager zfALFF was found in SSRI responder group compared to the nonresponders, which could serve as a significant predictor of SSRI response.

CONCLUSIONS

The fALFF of SMA may reflect the neuropathological mechanisms underlying OCD and neuroimaging underpinning of SSRI treatment response, which could serve as a brain-based guidance of clinical practice.