When the DSM-5 was published in 2012, hoarding disorder (HD) became a diagnosis separate from OCD. By that point, evidence also showed that patients with HD showed different abnormalities in information processing than patients with OCD.
Dr. Mathews and her team explored brain activation patterns using functional magnetic resonance imaging (fMRI) in patients with HD and OCD, as well as a healthy control group. Using this form of brain imaging, they searched for areas of overlap and separation between HD and OCD; ultimately, they found that these two groups had different patterns of brain activation when doing tasks that required them to inhibit automatic responses or pay attention to two competing aspects of the same image. People with HD had more activity in areas of the brain’s frontal cortex (reasoning, decision making, and complex cognition) and visual processing areas than people with OCD and the control group. People with OCD showed differences in the frontal cortex compared to the control group as well. This study contributed to research confirming that, on the level of brain regions, HD and OCD work differently, and that HD is indeed more separate from OCD than initially believed.
Hough, C.M., Luks, T.L., Lai, K., Vigil, O., Guillory, S., Nongpiur, A., Fekri, S.M., Kupferman, E., Mathalon, D.H., & Mathews C.A. (2016). Comparison of brain activation patterns during executive function tasks in hoarding disorder and non-hoarding OCD. Psychiatry Research: Neuroimaging, 255, 50-59. doi:10.1016/j.pscychresns.2016.07.007
Norman, L.J., Taylor, S.F., Liu, Y., Radua, J., Chye, Y., De Wit, S.J., Huyser, C., Isik Karahanoglu, F., Luks, T., Manoach, D., Mathews, C., Rubia, K., Suo, C., van den Heuvel, O.A., Yücel, M., & Fitzgerald, K. (2019). Error processing and inhibitory control in obsessive-compulsive disorder: A meta-analysis using statistical parametric maps. Biological Psychiatry, 85(9), 713-725. doi:10.1016/j.biopsych.2018.11.010