Although the initial plan of this study by Dr. Whiteside and his team was to understand the treatment effects of cognitive behavioral therapy and medication on OCD through the use of magnetic resonance spectroscopy (MRS; a form of neuroimaging that measures biochemical brain changes), their research led to an investigation of the brain related to OCD and anxiety. The brains of 15 participants with OCD and 15 healthy controls were scanned using MRS, with a special focus on the caudate nucleus (a brain region associated with movement and learning) and the orbitofrontal cortex (OFC; a brain region responsible for decision making which is linked to multiple regions related to emotion, reward, and cognition). The study found specific neurochemical markers in the brains of participants with OCD, such as increased glutamate and glutamine (associated with excitatory neurotransmitters) (with greater levels associated with more severe symptoms) and N-acetyl-l-aspartic acid relative to creatine (associated with neuronal viability) in the OFC (with lower levels associated with more severe symptoms), as well as lower levels of myo-inositol relative to creatine (associated with phospholipid metabolism) in the head of the caudate nucleus (unassociated with OCD severity, but related to anxiety). This study was the first to use MRS to scan the OFC and head of the caudate nucleus in OCD patients, and contributed to knowledge regarding neurotransmitters related to OCD.
*Whiteside, S.P., Port, J.D., Deacon, B.J., & Abramowitz, J.S. (2006). A magnetic resonance spectroscopy investigation of obsessive-compulsive disorder and anxiety. Psychiatry Research Neuroimaging, 146, 137-147. https://doi.org/10.1016/j.pscychresns.2005.12.006