There have been more than a few studies on gray matter abnormalities in Fibromyalgia. Hell, I distinctly remember the one that specified certain atrophying in the brain, that could be accounted for because we have chronic pain. This particular study is a meta- analysis of those said studies to see what exactly we can say about gray matter abnormalities. (A meta-analysis of voxel-based morphometric studies. Semin Arthritis Rheum. 2016 Dec; 46(3):330-337). The time frame looked at is January 2000 to September 2015.
Seven studies, reporting nine comparisons and including a grand total of 180 fibromyalgia patients and 126 healthy controls, were included in the meta-analyses. In fibromyalgia patients compared with healthy controls, regional GM decreases were consistently found in the bilateral anterior cingulate / paracingulate cortex/medial prefrontal cortex, the bilateral posterior cingulate/paracingulate cortex, the left parahippocampal gyrus/fusiform cortex, and the right parahippocampal gyrus/hippocampus. Regional GM increases were consistently found in the left cerebellum. Meta-regression demonstrated that age was correlated with GM anomalies in fibromyalgia patients.Prohealth
In conclusion, they identified a characteristic pattern of gray matter abnormalities within the medial pain system, default mode network, and cerebro-cerebellar circuits which suggest that fibromyalgia is a complex syndrome involving areas of the brain beyond those solely for chronic pain.
See also: Gray matter atrophy in fibromyalgia