Reactivation of variably sealed joints and permeability enhancement in geothermal reservoir rocks.

Hydraulic stimulation of enhanced deep geothermal reservoirs commonly targets pre-existing joint networks with the goal of increasing reservoir permeability. Here, we study the permeability and strength of joint-free and jointed Buntsandstein sandstones from the EPS-1 exploratory borehole at the Soultz-sous-Forêts geothermal site (France). The studied jointed samples contain naturally formed fractures that are variably filled with secondary mineralisation. We find that the permeability of these rocks is more sensitive to the presence and orientation of bedding than to the presence of joints at the scale of the samples: permeability is lowest in samples where bedding is oriented perpendicular to the direction of fluid flow. While well-sealed joints can act as barriers to fluid flow, partially filled joints neither inhibit nor promote fluid flow with respect to their joint-free counterparts. These samples were then deformed under triaxial conditions to assess (1) whether deformation reactivates pre-existing joints, and (2) how permeability changes as a result of deformation. We find that the mechanical response of the rocks depends on the extent to which joints are sealed. Well-sealed joints locally increase rock strength and experimentally induced fractures do not exploit pre-existing joint surfaces; partially sealed joints, by contrast, act as planes of weakness that localise strain. Although the permeability of all samples increased during deformation, permeability increase was largest in samples with poorly filled joints. We conclude that hydraulic stimulation operations must carefully consider the extent to which targeted joint networks are filled. Partially sealed joints are ideal targets for stimulation: these features act as planes of weakness within the rock mass and their reactivation can result in significant increases in permeability. By contrast, well-sealed joints may increase rock strength locally and may never reactivate during stimulation, making them poor targets for permeability enhancement. Supplementary Information: The online version contains supplementary material available at 10.1186/s40517-023-00271-5.

The Permeability of Porous Volcanic Rock Through the Brittle-Ductile Transition.

The permeability of volcanic rock controls the distribution of pore fluids and pore fluid pressure within a volcanic edifice, and is therefore considered to influence eruptive style and volcano deformation. We measured the porosity and permeability of a porous volcanic rock during deformation in the brittle and ductile regimes. In the brittle regime, permeability decreases by a factor of 2-6 up to the peak stress due the closure of narrow pore throats but, following shear fracture formation, remains approximately constant as strain is accommodated by sliding on the fracture. In the ductile regime, permeability continually decreases, by up to an order of magnitude, as a function of strain. Although compaction in the ductile regime is localized, permeability is not reduced substantially due to the tortuous and diffuse nature of the compaction bands, the geometry of which was also influenced by a pore shape preferred orientation. Although the evolution of the permeability of the studied porous volcanic rock in the brittle and ductile regimes is qualitatively similar to that for porous sedimentary rocks, the porosity sensitivity exponent of permeability in the elastic regime is higher than found previously for porous sedimentary rocks. This exponent decreases during shear-enhanced compaction toward a value theoretically derived for granular media, suggesting that the material is effectively granulating. Indeed, cataclastic pore collapse evolves the microstructure to one that is more granular. Understanding how permeability can evolve in a volcanic edifice will improve the accuracy of models designed to assist volcano monitoring and volcanic hazard mitigation.

Personality profiles in adults with attention deficit hyperactivity disorder (ADHD).

BACKGROUND: Previous studies suggested that the presence of ADHD in children and young adolescents may affect the development of personality. Whether or not the persistence of ADHD in adult life is associated with distinct personality patterns is still matter for debate. To address this issue, we compared the profiles of the Temperament and Character Inventory (TCI) that assesses personality dimensions in 119 adults ADHD and 403 controls. METHODS: ANCOVA were used to examine group differences (controls vs. ADHD and ADHD inattentive type vs. ADHD combined + hyperactive/impulsive types) in Temperaments and Characters. Partial correlation coefficients were used to assess correlation between TCI and expression and severity of symptoms of ADHD. RESULTS: High novelty seeking (NS), harm avoidance (HA) and self-transcendence (ST) scores as well as low self-directedness (SD) and cooperativeness (C) scores were associated with ADHD diagnosis. Low SD was the strongest personality trait associated with adult ADHD. Cases with the ADHD inattentive type showed higher HA and lower SD scores compared to the combined and hyperactive/impulsive types. High HA scores correlated with inattention symptoms whereas high NS and ST scores were related to hyperactive symptoms. Finally low SD and high NS were associated with increased ADHD severity. CONCLUSIONS: Distinct temperaments were associated with inattentive versus hyperactive/impulsive symptoms supporting the heterogeneous nature of the disorder.

Porosity, permeability and 3D fracture network characterisation of dolomite reservoir rock samples.

With fractured rocks making up an important part of hydrocarbon reservoirs worldwide, detailed analysis of fractures and fracture networks is essential. However, common analyses on drill core and plug samples taken from such reservoirs (including hand specimen analysis, thin section analysis and laboratory porosity and permeability determination) however suffer from various problems, such as having a limited resolution, providing only 2D and no internal structure information, being destructive on the samples and/or not being representative for full fracture networks. In this paper, we therefore explore the use of an additional method - non-destructive 3D X-ray micro-Computed Tomography (µCT) - to obtain more information on such fractured samples. Seven plug-sized samples were selected from narrowly fractured rocks of the Hauptdolomit formation, taken from wellbores in the Vienna basin, Austria. These samples span a range of different fault rocks in a fault zone interpretation, from damage zone to fault core. We process the 3D µCT data in this study by a Hessian-based fracture filtering routine and can successfully extract porosity, fracture aperture, fracture density and fracture orientations - in bulk as well as locally. Additionally, thin sections made from selected plug samples provide 2D information with a much higher detail than the µCT data. Finally, gas- and water permeability measurements under confining pressure provide an important link (at least in order of magnitude) towards more realistic reservoir conditions. This study shows that 3D µCT can be applied efficiently on plug-sized samples of naturally fractured rocks, and that although there are limitations, several important parameters can be extracted. µCT can therefore be a useful addition to studies on such reservoir rocks, and provide valuable input for modelling and simulations. Also permeability experiments under confining pressure provide important additional insights. Combining these and other methods can therefore be a powerful approach in microstructural analysis of reservoir rocks, especially when applying the concepts that we present (on a small set of samples) in a larger study, in an automated and standardised manner.

Distinguishing borderline personality disorder from adult attention deficit/hyperactivity disorder: a clinical and dimensional perspective.

Adult attention deficit hyperactivity disorder (ADHD) is frequently associated with borderline personality disorder (BPD). As both disorders share some core clinical features they are sometimes difficult to distinguish from one another. The present work aimed to investigate differences in the expression of impulsivity, anger and aggression, quality of life as well as the number and severity of the comorbidities between ADHD, BPD, comorbid BPD-ADHD and control subjects. ADHD and BPD-ADHD patients showed a higher level of impulsivity than BPD and control subjects. BPD-ADHD patients had higher levels of substance abuse/dependence and higher levels of aggression than the other groups. Comorbid BPD-ADHD patients showed high levels of impulsivity and aggression, a characteristic that should draw the attention of clinicians on the necessity of providing an accurate diagnosis. The question also arises as to whether they represent a distinct clinical subgroup with specific clinical characteristics, outcomes and vulnerability factors.

Temperament personality profiles in suicidal behaviour: an investigation of associated demographic, clinical and genetic factors.

BACKGROUND: Personality traits have been suggested as possible risk factors for suicidal behaviours. Cloninger's model of personality (TCI), given its neurobiological background, might provide an ideal tool for the identification of dimensions associated with suicide attempt. METHODS: A number of 1333 suicide attempters and 589 non-suicide attempters suffering from different DSM-IV Axis I disorders were assessed using either the temperament and character inventory (TCI) or the tridimensional personality questionnaire (TPQ), as well as other self-report questionnaires evaluating dimensions associated with suicidal behaviour, such as impulsivity and anger traits. The severity of suicide attempts and the methods used were also assessed. Subjects were genotyped for polymorphisms within the key genes involved in monoaminergic pathways and the HPA axis. RESULTS: Compared with non-suicide attempters, suicide attempters scored higher for harm avoidance (HA) and novelty seeking (NS), and lower for self-directedness (SD). The difference was independent of Axis I disorders. Higher HA and NS scores were associated with a greater severity of suicidal behaviour. A multivariate model showed that HA was the single temperamental dimension independently related to suicide attempt history, beside impulsivity and anger-related traits. The genetic factors investigated did not play a significant role in modulating these temperamental dimensions. LIMITATIONS: The TCI was available for only half of the sample. CONCLUSIONS: Early detection of subjects displaying high HA and low SD, associated with high impulsivity and poor anger control, may help to prevent suicidal behaviours. Physicians should therefore be aware of these risk factors so that they can offer the best primary care intervention.

Active Reward Processing during Human Sleep: Insights from Sleep-Related Eating Disorder.

In this paper, we present two carefully documented cases of patients with sleep-related eating disorder (SRED), a parasomnia which is characterized by involuntary compulsive eating during the night and whose pathophysiology is not known. Using video-polysomnography, a dream diary and psychometric examination, we found that both patients present elevated novelty seeking and increased reward sensitivity. In light of new evidence on the mesolimbic dopaminergic implication in compulsive eating disorders, our findings suggest a role of an active reward system during sleep in the manifestation of SRED.

[Risk factors and psychosocial disability of treatment-resistant depression]. / Facteurs de risque et consé- quences socioprofessionnelles des dépressions chroniques et/ou résistantes.

Resistant and/or chronic depression has severe consequences on social and professional functioning. Clinical and health-economic studies allowed the identification of the main factors involved in these adverse outcomes. Some factors are illness-dependent or related to personal characteristics, while others are linked to a wide range of psychosocial stresses. Guidelines have been developed to improve the pharmacological treatment of resistant depression, but they are not easy to implement and therapeutic failures are frequent. The knowledge of the factors influencing the evolution of depressive syndromes gives an empirical basis to assess their consequences on work capacity. It should also guide public health policies.

Impulsivity, aggression and suicidal behavior in unipolar and bipolar disorders.

BACKGROUND: Predictors of suicidal behaviors (SB) in bipolar (BD) and major depressive disorder (MDD) patients are poorly understood. It has been recognized that behavioral dysregulation characterizes SB with traits of impulsivity and aggression being particularly salient. However, little is known about how these traits are segregated among mood disorder patients with and without a history of suicide attempt (SA). METHODS: This article aims to compare impulsivity and aggression between 143 controls, 138 BD and 186 MDD subjects with or without a history of SA. RESULTS: BD and MDD patients showed higher impulsivity scores (BIS-10 = 57.9 vs. 44.7, p < 0.0001) and more severe lifetime aggression than controls (Lifetime History of Aggression = 7.3 vs. 3.9, p < 0.0001). Whereas impulsivity helped to distinguish MDD subjects without a history of SA from those with such a history, this was not the case in BD subjects where no difference in impulsive traits was observed between BD without and with history of SA (57.2 vs. 63.2 for BIS-10; p = 0.259). Impulsive and aggressive traits were strongly correlated in suicide attempters (independently of the diagnosis) but not in non-suicide attempters. LIMITATIONS: Dimensional traits were not characterized at different stages of illness. CONCLUSIONS: Impulsivity, as a single trait, may be a reliable suicide risk marker in MDD but not in BD patients, and its strong correlation with aggressive traits seems specifically related to SB. Our study therefore suggests that the specific dimension of impulsive aggression should be systematically assessed in mood disorder patients to address properly their suicidal risk.

Genetic and epigenetic analysis of SSAT gene dysregulation in suicidal behavior.

It has recently been proposed that the SSAT gene plays a role in the predisposition to suicidal behavior. SSAT expression was found to be down-regulated in the brain of suicide completers. In addition, a single nucleotide polymorphism (SNP) rs6526342 was associated both with variation in SSAT expression and with suicidal behavior. In this study, we aimed to characterize the relationship between SSAT dysregulation and suicide behavior. To this end, we measured SSAT expression levels in the ventral prefrontal cortex (VPFC) of suicide completers (n = 20) and controls (n = 20) and found them to be significantly down-regulated in suicide victims (P = 0.007). To identify the basis of the regulation of SSAT expression, we performed an association analysis of 309 SNPs with SSAT transcript levels in 53 lymphoblastoid cell lines from the CEPH collection. We then examined the methylation status of the SSAT promoter region in males and females suicide completers and control subjects whose SSAT brain expression had been measured. We found no evidence to support a role for SNPs in controlling the level of SSAT expression. SSAT promoter methylation levels were not different between suicide completers and controls and did not correlate with SSAT expression levels. In addition, we found no indication of a genetic association between suicidal behavior and SNPs located within the SSAT gene. Our study provides new results which show that dysregulation of SSAT expression does play a role in suicide behavior. However, our data do not support any association between rs6526342 and variation in SSAT expression or suicidal behavior.

[Pharmacological treatment of attention-deficit/hyperactivity disorder in adults]. / Traitement pharmacologique du trouble déficit de l'attention avec hyperactivité de l'adulte.

Attention-deficit/hyperactivity disorder (ADHD) is not restricted to childhood or adolescence, but often persists into adulthood, with an estimated prevalence of 4% to 5%. It often comes along with a significant negative impact on educational, occupational and social outcomes in adults. It is important to pay particular attention to the screening of this neuropsychiatric disorder. Indeed, numerous controlled studies have clearly established the effectiveness of psychostimulants, and to a lesser extent of some antidepressants, in the treatment of adult ADHD. The pharmacological treatment of this disorder should aim to control symptoms and limit the long-term consequences of dysfunctional behaviours.

Association between brain-derived neurotrophic factor gene and a severe form of bipolar disorder, but no interaction with the serotonin transporter gene.

BACKGROUND: Recent data suggest that brain-derived neurotrophic factor (BDNF) and the serotonergic system are involved and interact in major depressive disorder and suicidal behavior (SB). Several family and population-based studies have reported associations between the BDNF gene and serotonin-related genes, specifically the serotonin transporter (5HTT) gene, with bipolar disorder (BD) and SB. However, despite the fact that gene-by-gene interaction between BDNF and 5HTT has been demonstrated in monoamine deficiencies in animals, this kind of interaction has never been tested in humans. Our hypothesis is that some BDNF and 5HTT polymorphisms might confer increased risk for BD and SB and that both genes may interact with each other. METHODS: To test this hypothesis, we genotyped the most common BDNF polymorphisms, G196A (Val66Met), A-633T and BDNF-LCPR, as well as 5HTT (5HTT-LPR), in 447 BD patients and 370 controls. RESULTS: We replicated the association previously reported between BDNF G196A (Val66Met) polymorphism and BD. We also observed a correlation between the number of G196 alleles and short alleles of 5HTT-LPR and the severity of SB in BD. However, we found no significant interaction between these two markers. CONCLUSIONS: These results suggest that BDNF G196A as well as 5HTT-LPR polymorphisms confer risk for SB in BD, but we did not observe any evidence for an interaction between them.

Social phobia is associated with suicide attempt history in bipolar inpatients.

OBJECTIVES: In an attempt to reduce the phenotypical heterogeneity in an ongoing genetic study of suicidal behavior, we investigated the impact of comorbid anxiety disorders on suicidal behavior in bipolar disorder (BD) patients. METHODS: Anxiety disorders were compared in 406 BD I and BD II patients with or without lifetime history of suicide attempt. RESULTS: Among anxiety disorders, only social phobia (SP) was significantly associated with history of suicide attempt in BD [p<0.001, odds ratio 4.26 (2.284-7.946)]. Moreover, onset of SP was found to precede onset of BD. CONCLUSIONS: This result suggests that SP is an important risk factor for suicidal behavior in BD. Further studies are required to determine whether comorbid SP may help to identify a more homogeneous BD sub-group, especially when studies of suicidal behavior are conducted. A second question is whether SP identifies a sub-group of subjects with BD who have a more severe illness course and whether treatment of SP with selective serotonin reuptake inhibitor (SSRI) antidepressants is associated with improvement or worsening of the course of BD.

Catechol-O-methyltransferase polymorphism (COMT) in suicide attempters: a possible gender effect on anger traits.

Anger-related personality traits are considered contributory risk factors for suicidal behavior. According to twin studies, they are partially under genetic control and their various clinical expressions have been associated with serotonergic and catecholaminergic activities. A functional polymorphism on the human catechol-O-methyltransferase (COMT) gene, which codes for the catecholamines inactivating enzyme COMT, has been shown to influence aggressive and anger-related traits in various clinical populations. The aim of the present study was to investigate the association between anger traits (as characterized by the State-Trait Anger Expression Inventory, STAXI) and COMT Val158Met polymorphism in suicide attempters (n = 427) and control subjects (n = 185). Results showed that the high activity genotype (Val/Val) was more frequent in suicide attempters than in normal controls. Moreover, the Val/Val genotype markedly affected the scores on two STAXI subscales--Trait Anger and Anger Control--in female suicide attempters, thus suggesting a possible gender effect of the COMT genotype on a stable personality trait. These results are discussed in the light of recently published data on the effect of COMT Val158Met polymorphism on different cognitive and behavioral traits.

No human tryptophan hydroxylase-2 gene R441H mutation in a large cohort of psychiatric patients and control subjects.

BACKGROUND: It was recently reported that a rare functional variant, R441H, in the human tryptophan hydroxylase-2 gene (hTPH2) could represent an important risk factor for unipolar major depression (UP) since it was originally found in 10% of UP patients (vs. 1.4% in control subjects). METHODS: We explored the occurrence of this variation in patients with affective disorders (n = 646), autism spectrum disorders (n = 224), and obsessive-compulsive disorder (OCD) (n = 201); in healthy volunteers with no psychiatric disorders (n = 246); and in an ethnic panel of control individuals from North Africa, Sub-Saharan Africa, India, China, and Sweden (n = 277). RESULTS: Surprisingly, we did not observe the R441H variant in any of the individuals screened (3188 independent chromosomes). CONCLUSIONS: Our results do not confirm the role of the R441H mutation of the hTPH2 gene in the susceptibility to UP. The absence of the variant from a large cohort of psychiatric patients and control subjects suggests that the findings reported in the original study could be due to a genotyping error or to stratification of the initial population reported. Additional data by other groups should contribute to the clarification of the discrepancy between our results and those previous published.

Personality traits as intermediary phenotypes in suicidal behavior: genetic issues.

A genetic contribution to the risk of suicidal behavior is now supported by many studies. It probably involves specific factors acting on their own, independently of the genetic transmission of associated psychiatric disorders. A history of childhood maltreatment, adverse events, psychosocial stress, psychological traits and major psychiatric disorders all appear to contribute to the global risk of suicide attempt or completion. The interplay between previously identified risk factors, different as they are in nature and degree of complexity, still remains to be clarified. A stress-diathesis model has been proposed, where trait-like genetic and developmental risk factors (the diathesis) interact through still unknown mechanisms with actual (stress-related) factors to create the conditions for a suicidal gesture. Disentangling the effects of these risk factors, and specifically the effects of the genetic factors influencing these different pathological conditions, appears to be a difficult task. Indeed the results of candidate gene association studies suggest that genetic vulnerability factors for various related psychiatric phenotypes (major psychiatric disorders and personality traits) partly overlap with more specific factors predisposing to suicidal behavior. Personality traits are partly under genetic control and may be closer to the genetic effects than psychiatric syndromes. We review here the available data on the genetics of personality traits presumably involved in suicidal behavior, focusing on the association studies carried out with serotonin-related genes. We suggest that future studies on the genetic vulnerability to suicidal behavior should include the investigation of endophenotypes, with the aim of deciphering the mechanisms underlying the genetic susceptibility to these closely associated phenotypes.

No association between DUP25 and anxiety disorders.

Gratacos et al. [2001: Cell 106:367-379] described an interstitial duplication dup(15)q24q26 (DUP25) in patients with anxiety disorders; this duplication was found in approximately 90% of patients and in 7% of controls. In order to determine if DUP25 is present in additional individuals susceptible to panic attacks, we tested 44 patients with anxiety disorders, using probes 251c23 and 216c14 mapping in the 15q24 and 15q26 region. We have not detected any DUP25. Our results suggest that DUP25 is not common in people with anxiety disorders in the population tested here.

No association between non-violent suicidal behavior and the serotonin transporter promoter polymorphism.

There is compelling evidence that suicidal behavior is associated with the dysfunction of the serotonin system. A functional polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) was recently identified and the presence of the short allele was associated with lower gene expression, lower 5-HT uptake and violent suicidal behavior. Thus, we attempted to determine whether 5-HTTLPR is also involved in the susceptibility to non-violent suicidal behavior. We compared the genotype from 166 West European Caucasians who attempted suicide by a non-violent mean with 139 controls with no history of suicidal behavior from the same ethnic origin. The frequencies of the S allele and the SS genotype in the sample who attempted non-violent suicide were not statistically different to those in the controls. Thus, the genetically altered expression of the 5-HT transporter might be associated with more severe or violent suicidal behavior, but not with non-violent suicidal behavior.