Affective disorders impact prevalence of Flavonifractor and abundance of Christensenellaceae in gut microbiota.

Background Affective disorders (AD) have been associated with a higher prevalence of the gut Flavonifractor genus and a lower abundance of the gut Christensenellaceae family. Objective and methods By pooling two independent study samples of patients with AD (n = 176), their unaffected first-degree relatives (n = 70) and healthy controls (n = 101) we aimed to replicate and extend our prior findings of differential Flavonifractor prevalence and Christensenellaceae abundance when comparing patients with AD and healthy controls. The gut microbiota was profiled using 16S rRNA gene amplicon sequencing. Results The pattern of higher prevalence of Flavonifractor and lower Centered Log-Ratio (CLR) abundance of Christensenellaceae was associated with AD. In generalized linear models the CLR abundance of Christensenellaceae was lower in patients with AD (p = 0.024), and in smokers (p = 1.9*10-4), and inversely associated with increasing waist circumference (p = 0.031). The prevalence of Flavonifractor was higher in patients with AD (p = 0.033) and in smokers (p = 0.036). No impact of psychotropic medication was found. The CLR abundance of Christensenellaceae (p = 0.041), but not the prevalence of Flavonifractor (p = 0.20) could distinguish non-smoking patients with AD from non-smoking healthy controls, whereas no such associations were found in smokers. Unaffected relatives neither differed from patients with AD nor from healthy controls. Conclusion Compared with findings in healthy controls, AD was associated with a significantly lower CLR abundance of the health-linked Christensenellaceae and a significantly higher prevalence of Flavonifractor; findings that are associated with enhanced oxidative stress and systemic low-grade inflammation. If our observations are validated in future independent studies, they support the notion that parts of aberrant gut microbiota are shared by AD and states of dysmetabolism.

S100B and brain derived neurotrophic factor in monozygotic twins with, at risk of and without affective disorders.

BACKGROUND: The calcium binding protein S100B and brain derived neurotrophic factor (BDNF) are both biomarkers implicated in neuronal processes in the central nervous system and seem to be associated with affective disorders. Here we investigated both markers in a sample of monozygotic (MZ) twins with, at risk of and without affective disorders, aiming to evaluate whether these markers have a role as causal factors- or trait markers for affective disorders. METHOD: We measured serum S100B and plasma BDNF levels in 204 monozygotic twins (MZ) with unipolar or bipolar disorder in remission or partial remission (affected), their unaffected co-twins (high-risk) and twins with no personal or family history of affective disorder (low-risk). RESULTS: No significant group differences in S100B and BDNF levels were found between the three groups. Exploratory analysis revealed that higher S100B levels were correlated with lower cognitive performance. LIMITATIONS: The cross-sectional design cannot elucidate the two neuronal biomarkers role as causal factors. We would have preferred a higher sample size in the high- and low-risk groups. CONCLUSION: The present result did not support a role for S100B and BDNF as neither causal factors nor trait markers for affective disorders. Elevated S100B levels may associate with impaired cognition, but further studies are warranted.

Are remitted affective disorders and familial risk of affective disorders associated with metabolic syndrome, inflammation and oxidative stress? - a monozygotic twin study.

BACKGROUND: Metabolic syndrome (MetS) is associated with reduced life expectancy in patients with affective disorders, however, whether MetS also plays a role before the onset of affective disorder is unknown. We aimed to investigate whether MetS, inflammatory markers or oxidative stress act as risk factors for affective disorders, and whether MetS is associated with increased inflammation and oxidative stress. METHODS: We conducted a high-risk study including 204 monozygotic (MZ) twins with unipolar or bipolar disorder in remission or partial remission (affected), their unaffected co-twins (high-risk) and twins with no personal or family history of affective disorder (low-risk). Metabolic Syndrome was ascertained according to the International Diabetes Federation (IDF) criteria. Inflammatory markers and markers of oxidative stress were analyzed from fasting blood and urine samples, respectively. RESULTS: The affected and the high-risk group had a significantly higher prevalence of MetS compared to the low-risk group (20% v. 15% v. 2.5%, p = 0.0006), even after adjusting for sex, age, smoking and alcohol consumption. No differences in inflammatory and oxidative markers were seen between the three groups. Further, MetS was associated with alterations in inflammatory markers, and oxidative stress was modestly correlated with inflammation. CONCLUSION: Metabolic syndrome is associated with low-grade inflammation and may act as a risk factor and a trait marker for affective disorders. If confirmed in longitudinal studies, this suggests the importance of early intervention and preventive approaches targeted towards unhealthy lifestyle factors that may contribute to later psychopathology.

Neural response during emotion regulation in monozygotic twins at high familial risk of affective disorders.

PURPOSE: We investigated the neural correlates of emotion regulation and -reactivity in adult unaffected monozygotic twins with a co-twin history of unipolar or bipolar disorder (high-risk), remitted or partially remitted twins with a personal history of unipolar or bipolar disorder (affected) and twins with no personal or first-degree family history of unipolar or bipolar disorder (low-risk). METHODS: We assessed 37 high-risk, 56 affected and 28 low-risk participants. Participants viewed unpleasant and neutral pictures during functional magnetic resonance imaging and were instructed to down-regulate their emotional response through reappraisal or mental imagery, as well as to maintain the elicited emotion. RESULTS: After adjusting for subsyndromal depressive symptoms, bilateral supplementary motor areas, posterior dorsal anterior cingulate cortices and the left frontal eye field showed less activity during reappraisal of unpleasant pictures in high-risk than low-risk participants. Notably, affected participants did not differ from high-risk or low-risk participants in neural response during reappraisal. There were no group differences in ventrolateral prefrontal cortex seed based functional connectivity during reappraisal or neural response during mental imagery or emotional reactivity. CONCLUSION: Lesser response in dorsal midline areas might reflect familial risk related abnormalities during down regulation of emotional reactivity through reappraisal.