A study on diffusion tensor imaging in patients with untreated first-episode obsessive-compulsive disorder

Human microbiota from drug-naive patients with obsessive-compulsive disorder drives behavioral symptoms and neuroinflammation via succinic acid in mice

Emerging evidence suggests that the gut microbiota is closely related to psychiatric disorders. However, little is known about the role of the gut microbiota in the development of obsessive-compulsive disorder (OCD). Here, to investigate the contribution of gut microbiota to the pathogenesis of OCD, we transplanted fecal microbiota from first-episode, drug-naive OCD patients or demographically matched healthy individuals into antibiotic-treated specific pathogen-free (SPF) mice and showed that colonization with OCD microbiota is sufficient to induce core behavioral deficits, including abnormal anxiety-like and compulsive-like behaviors. The fecal microbiota was analyzed using 16 S rRNA full-length sequencing, and the results demonstrated a clear separation of the fecal microbiota of mice colonized with OCD and control microbiota. Notably, microbiota from OCD-colonized mice resulted in injured neuronal morphology and function in the mPFC, with inflammation in the mPFC and colon. Unbiased metabolomic analyses of the serum and mPFC region revealed the accumulation of succinic acid (SA) in OCD-colonized mice. SA impeded neuronal activity and induced an inflammatory response in both the colon and mPFC, impacting intestinal permeability and brain function, which act as vital signal mediators in gut microbiota-brain-immune crosstalk. Manipulations of dimethyl malonate (DM) have been reported to exert neuroprotective effects by suppressing the oxidation of accumulated succinic acid, attenuating the downstream inflammatory response and neuronal damage, and can help to partly improve abnormal behavior and reduce neuroinflammation and intestinal inflammation in OCD-colonized mice. We propose that the gut microbiota likely regulates brain function and behaviors in mice via succinic acid signaling, which contributes to the pathophysiology of OCD through gut-brain crosstalk and may provide new insights into the treatment of this disorder.

Comparison of accidental findings of brain magnetic resonance imaging of patients with obsessive-compulsive disorder and healthy controls

BACKGROUND

Abnormalities in brain magnetic resonance imaging (MRI) have been reported in drug-naive and chronic patients with obsessive-compulsive disorder (OCD). The Fazekas scale is a method used to categorize and grade the severity of white matter hyperintensities (WMH) in brain MRI. These lesions can be indicative of various neurological conditions, particularly small vessel disease or cerebrovascular pathology.

METHODS

Brain MRIs of patients followed up with the diagnosis of OCD were retrospectively analyzed. 58 OCD (36 females, 22 males) and 58 healthy controls (HC) (30 females, 28 males) were included in the study. Age, gender, and brain MRI findings of the participants were recorded.

RESULTS

The mean ages of the OCD and HC groups were 33.4 ± 10.6 and 35.9 ± 9.3. There was no difference between the groups in terms of mean ages and gender distribution (p = 0.180 and p = 0.260, accordingly). Generalized cerebral atrophy was more common in patients with OCD than in HC (p = 0.008). Fazekas grade 1 was detected in 17.2% of the patients with OCD and 1.7% of HC. Accordingly, it was significantly more common in Fazekas grade 1 OCD patients (p = 0.002). Fazekas grade 2 was detected in only 2 patient with OCD. CVI was present in 20.7% of the patients with OCD and 1.7% of HC. There was a significant difference between the groups regarding CVI (p = 0.001). Ethmoidal thickening was more common in patients with OCD than in HC (p = 0.004). The YBOCS scores and ages of OCD patients with Fazekas grade 1 and 2 were significantly higher than those of patients with Fazekas grade 0. Likewise, the YBOCS scores and ages of OCD patients with generalized cerebral atrophy were significantly higher than those of patients without atrophy.

CONCLUSION

It is understood from the present study's findings that CVI, a neurodevelopmental malformation, is more common in patients with OCD. Due to the potential relationship of this anomaly with neuronal migration, it would be appropriate to pay attention to OCD symptoms in individuals with CVI and to perform white matter examination on brain imaging. In future studies, Fazekas grade can be evaluated in drug-naive OCD patients, and data on the pre-disease period can be obtained.

White matter microstructural abnormalities and gray matter volume alterations in obsessive-compulsive disorder: A coordinate-based meta-analysis

OBJECTIVE

A comprehensive meta-analysis using correlated coordinate data to explore abnormalities in white matter (WM) microarchitecture and changes in gray matter volume (GMV) in patients with obsessive-compulsive disorder (OCD).

METHODS

We reviewed 23 reported studies of diffusion tensor imaging (DTI) in OCD patients. The differences in WM fractional anisotropy (FA) between OCD patients and healthy controls (HCs) were investigated using tract-based spatial statistics (TBSS) and voxel-based analysis (VBA), respectively, and the results of the two methods were compared. In addition, we will explore changes in OCD GMV by analyzing studies (n = 21) using the voxel-based morphometry (VBM) approach and comparing the difference between adults and adolescents.

RESULTS

In the pooled meta-analysis, WM study results presented that compared with HCs, OCD patients had higher FA in right lenticular nucleus (putamen), and lower FA in corpus callosum (CC), left insula, right cerebellum (hemispheric lobule), right gyrus rectal and left inferior parietal gyri. However, in subgroup analysis, there was a significant difference in FA changes between TBSS and VBA in OCD patients compared with HCs. In addition, we found that the GMV of OCD patients was significantly increased in left striatum and left precentral gyrus, and significantly decreased in right inferior frontal gyrus triangular part, right superior temporal gyrus and right hippocampus. Compared with adolescents, adult patients have increased GMV in left lenticular nucleus putamen.

CONCLUSION

The meta-analysis showed that OCD patients had abnormal WM microarchitecture and altered GMV. These changes may be closely related to the pathophysiological mechanism of the disease.