The gut microbiome and inflammation in obsessive-compulsive disorder patients compared to age- and sex-matched controls: a pilot study.

OBJECTIVE: To compare the gut microbiome profile (by way of taxon analysis and indices of ß- and α-diversity) and inflammatory markers (C-reactive protein [CRP], interleukin-6[IL-6] and tumour necrosis factor-α [TNF-α]) of obsessive-compulsive disorder (OCD) outpatients and non-psychiatric community controls. METHODS: We collected morning stool and blood samples from 21 non-depressed, medication-free OCD patients and 22 age- and sex-matched non-psychiatric community controls. Microbiota analysis was performed using Illumina sequencing of the V3 region of 16S rRNA; serum CRP samples were analysed using immunoturbidimetry and plasma IL-6/TNF-α were examined by high-sensitivity ELISA. Multiple comparisons were corrected for using the false discovery rate (α = 0.05). RESULTS: Compared to controls, the OCD group presented lower species richness/evenness (α-diversity, Inverse Simpson) and lower relative abundance of three butyrate producing genera (Oscillospira, Odoribacter and Anaerostipes). Compared to controls, mean CRP, but not IL-6 and TNF-α, was elevated OCD patients. CRP revealed moderate to strong associations with psychiatric symptomatology. CONCLUSION: To our knowledge, this is the first investigation of the gut microbiome in OCD. In addition, our findings lend further support for the potential association of inflammation and OCD. These results suggest the gut microbiome may be a potential pathway of interest for future OCD research.

Evidence for the involvement of the hippocampus in the pathophysiology of schizophrenia.

The hippocampus, a medial temporal lobe structure, is often considered to play an important role in the pathophysiology of schizophrenia. Recent developments of neuroimaging and molecular postmortem techniques have significantly increased our ability to study the role of discrete brain regions in the pathophysiology of schizophrenia. This article describes animal models, structural, histological, molecular biology, and neuropsychological evidence for the involvement of the hippocampus in the pathophysiology of schizophrenia. The major findings in schizophrenic patients are decreased volumes, hypometabolism, and cytoarchitectural abnormalities which are more robust on the left hippocampus, as well as verbal memory impairment. It is yet to be determined whether these changes are neurodevelopmental or neurodegenerative in nature. Overall, these findings indicate that there are subtle changes in the hippocampus of schizophrenic patients. More comprehensive and focused hippocampal research in schizophrenia is required to elucidate the contribution of this intriguing brain structure to the pathophysiology of schizophrenia.

Decreased platelet peripheral-type benzodiazepine receptors in adolescent inpatients with repeated suicide attempts.

BACKGROUND: Peripheral-type benzodiazepine receptors (PBR) are responsible for mitochondrial cholesterol uptake, the rate limiting step of steroidiogenesis. They have been shown to be increased after acute stress, and decreased during exposure to chronic stressful conditions, and in patients with generalized anxiety disorder and post-traumatic stress disorder. In view of the proven connection between adolescent suicidal behavior and stress, we hypothesized that PBR may be decreased in the suicidal adolescent population. METHODS: We measured [3H] PK 11195 binding to platelet membrane in nine adolescent (age 13-20 years) inpatients with a history of at least three suicidal attempts and ten age-matched psychiatric inpatients with no history of suicide attempts. Suicidality was assessed with the Suicide Risk Scale (SRS), and symptom severity with the Beck Depression Inventory, State-Trait Anxiety Inventory (STAI), Overt Aggression Scale (OAS), and Impulsivity Scale (IS). RESULTS: Suicide Risk Scale scores were significantly higher in the suicidal group. The suicidal group showed a significant decrease in platelet PBR density (-35%) compared to the controls (p < 0.005). CONCLUSIONS: Our results of PBR depletion in adolescent suicide are in accordance with the findings in patients with generalized anxiety disorder and posttraumatic stress disorder and lend further support to the role of PBR in human response to chronic stress in adolescent suicide.