Total plasma l-tryptophan, free l-tryptophan and competing amino acid levels in a homicidal male adolescent with conduct disorder

Plasma Lysophosphatidic Acid Concentrations in Sex Differences and Psychiatric Comorbidity in Patients with Cocaine Use Disorder

We have recently reported sex differences in the plasma concentrations of lysophosphatidic acid (LPA) and alterations in LPA species in patients with alcohol and cocaine use disorders. Preclinical evidence suggests a main role of lysophosphatidic acid (LPA) signaling in anxiogenic responses and drug addiction. To further explore the potential role of the LPA signaling system in sex differences and psychiatric comorbidity in cocaine use disorder (CUD), we conducted a cross-sectional study with 88 patients diagnosed with CUD in outpatient treatment and 60 healthy controls. Plasma concentrations of total LPA and LPA species (16:0, 18:0, 18:1, 18:2 and 20:4) were quantified and correlated with cortisol and tryptophan metabolites [tryptophan (TRP), serotonin (5-HT), kynurenine (KYN), quinolinic acid (QUIN) and kynurenic acid (KYNA)]. We found sexual dimorphism for the total LPA and most LPA species in the control and CUD groups. The total LPA and LPA species were not altered in CUD patients compared to the controls. There was a significant correlation between 18:2 LPA and age at CUD diagnosis (years) in the total sample, but total LPA, 16:0 LPA and 18:2 LPA correlated with age at onset of CUD in male patients. Women with CUD had more comorbid anxiety and eating disorders, whereas men had more cannabis use disorders. Total LPA, 18:0 LPA and 20:4 LPA were significantly decreased in CUD patients with anxiety disorders. Both 20:4 LPA and total LPA were significantly higher in women without anxiety disorders compared to men with and without anxiety disorders. Total LPA and 16:0 LPA were significantly decreased in CUD patients with childhood ADHD. Both 18:1 LPA and 20:4 LPA were significantly augmented in CUD patients with personality disorders. KYNA significantly correlated with total LPA, 16:0 LPA and 18:2 LPA species, while TRP correlated with the 18:1 LPA species. Our results demonstrate that LPA signaling is affected by sex and psychiatric comorbidity in CUD patients, playing an essential role in mediating their anxiety symptoms.

The role of tryptophan metabolic pathway in children with attention deficit hyperactivity disorder with and without comorbid oppositional defiant disorder and conduct disorder

Accumulating data presented that tryptophan metabolic pathway (TMP) may play a role in attention-deficit/hyperactivity disorder (ADHD). However, no study have investigated potential role of TMP in disruptive behavior disorders coexisting with ADHD. This study compared serum levels of tryptophan, kynurenine, kynurenic acid, 3-hydroxykynurenine and 3-hydroxyantranilic acid in medication-free children with ADHD combined presentation (ADHD-C), with ADHD-C and oppositional defiant disorder (ODD), and with ADHD-C and conduct disorder (CD) versus healthy controls. The study also compared several ratios that are previously suggested to reflect the activities of the KP enzymes (kynurenine/tryptophan, kynurenic acid/kynurenine, 3-hydroxykynurenine/kynurenine) or neuroprotective activity (kynurenic acid/3-hydroxykynurenine) among groups. A total of 122 patients were enrolled: 46 children with ADHD-C alone, 43 children with ADHD-C+ODD, 33 children with ADHD-C+CD and 50 healthy controls. Targeted biochemical molecules were assessed by liquid chromatography-mass spectrometry/mass spectrometry. Compared to control group, serum kynurenine levels were significantly higher in the ADHD-C group, serum 3-hydroxykynurenine levels were significantly lower in the ADHD-C and ADHD-C+ODD groups, the serum kynurenic acid/kynurenine ratio was significantly higher in the ADHD-C, ADHD-C+ODD and ADHD-C+CD groups, and the serum 3-hydroxykynurenine/kynurenine ratio was significantly lower in the ADHD-C group. These findings suggest that TMP may play a role in the pathophysiology of ADHD-C.

Tryptophan in health and disease

Tryptophan (TRP), an essential amino acid in mammals, is involved in several physiological processes including neuronal function, immunity, and gut homeostasis. In humans, TRP is metabolized via the kynurenine and serotonin pathways, leading to the generation of biologically active compounds, such as serotonin, melatonin and niacin. In addition to endogenous TRP metabolism, resident gut microbiota also contributes to the production of specific TRP metabolites and indirectly influences host physiology. The variety of physiologic functions regulated by TRP reflects the complex pattern of diseases associated with altered homeostasis. Indeed, an imbalance in the synthesis of TRP metabolites has been associated with pathophysiologic mechanisms occurring in neurologic and psychiatric disorders, in chronic immune activation and in the immune escape of cancer. In this chapter, the role of TRP metabolism in health and disease is presented. Disorders involving the central nervous system, malignancy, inflammatory bowel and cardiovascular disease are discussed.

Biomarkers in aggression

Aggressive behavior exerts an enormous impact on society remaining among the main causes of worldwide premature death. Effective primary interventions, relying on predictive models of aggression that show adequate sensitivity and specificity are currently lacking. One strategy to increase the accuracy and precision of prediction would be to include biological data in the predictive models. Clearly, to be included in such models, biological markers should be reliably associated with the specific trait under study (i.e., diagnostic biomarkers). Aggression, however, is phenotypically highly heterogeneous, an element that has hindered the identification of reliable biomarkers. However, current research is trying to overcome these challenges by focusing on more homogenous aggression subtypes and/or by studying large sample size of aggressive individuals. Further advance is coming by bioinformatics approaches that are allowing the integration of inter-species biological data as well as the development of predictive algorithms able to discriminate subjects on the basis of the propensity toward aggressive behavior. In this review we first present a brief summary of the available evidence on neuroimaging of aggression. We will then treat extensively the data on genetic determinants, including those from hypothesis-free genome-wide association studies (GWAS) and candidate gene studies. Transcriptomic and neurochemical biomarkers will then be reviewed, and we will dedicate a section on the role of metabolomics in aggression. Finally, we will discuss how biomarkers can inform the development of new pharmacological tools as well as increase the efficacy of preventive strategies.

Tryptophan via serotonin/kynurenine pathways abnormalities in a large cohort of aggressive inmates: markers for aggression

Aggressive behavior is one of the most challenging symptoms in psychiatry, and biological markers for aggression lack of large sample validations. Serotonin (5-HT) and other neuroactive compounds deriving from Tryptophan (Trp), including kynurenine (Kyn), have not yet been investigated in large cohorts of aggressive individuals to validate their potential as biomarkers of aggression. In 361 male inmates we measured serum levels of Trp, 5-hydroxytryptophan, 5-HT, Kyn, the ratios 5-HT/Trp∗1000 and Kyn/Trp∗1000, and performed Structured Clinical Interview for DSM-IV Axis-I and -II Disorders (SCID-I and -II), global assessment of functioning (GAF), and scales for aggressive behavior, impulsivity, adult attention-deficit/hyperactivity disorder (ADHD), and intelligent quotient (IQ). Aggressive compared to non-aggressive inmates exhibited lower Trp and Kyn serum levels but higher levels of 5-HT and 5-HT/Trp∗1000, higher levels of impulsivity and ADHD indices, lower IQ and GAF, higher prevalence of mood disorders, drug abuse/dependence, and borderline, conduct and antisocial behaviors. Interestingly, Kyn/Trp∗1000 was positively correlated to the number of severe aggressive acts (r=0.593, P<0.001). After adjusting for confounding factors, logistic regression analysis indicated that 5-HT/Trp∗1000, antisocial behavior, and GAF were predictors of aggressive behavior. The model combining these three predictors had an area under the ROC curve of 0.851 (95% CI 0.806-0.895). This study indicates that while circulating Trp is reduced in aggressive individuals, the combination of biological (5-HT/Trp ratio) and psychopathological (antisocial behavior and GAF) markers discriminates between aggressive and non-aggressive behavior suggesting the potential of a multi-marker approach in psychiatry given the heterogenic nature of mental diseases.

Adolescence: Does good nutrition = good behaviour?

Adolescence is often associated with exploring boundaries, rapid growth, hormones and pimples. A stable feature of this turbulent age is that these young people are highly over-represented in the criminal justice system. Adolescents account for disproportionate proportion of police-recorded crimes, and this seems to be a cross-cultural phenomenon. Furthermore, disaffected young people often have limited routine access to healthy foods and make poor food choices. These people form a large proportion of the prison population and there are concerns that insufficient attention is paid to their health. Hence their diet tends to be poor compared with international standards of dietary adequacy, which typically are set to protect the heart but not for optimal brain function. Thus, it has been posited that a poor diet may be a modifiable causal factor in antisocial behaviours. We tested what happened to the behaviour of violent young adult prisoners (18-21years) when nutrients missing from their diets were reinstated. We used food supplements as an analogue of a better diet because it provided the possibility of a placebo control. On a random basis, where neither the volunteers, prison staff nor researchers in the prison knew who was getting which type, 231 volunteers were given either placebo or real capsules containing broadly the daily requirements of vitamins, minerals and essential fatty acids. The number of proven offences committed by each prisoner was monitored before and while taking supplements. The result was that those who received the extra nutrients committed significantly (26.3%) fewer offences compared with placebos. Those consuming real supplements for at least 2 weeks committed 37% fewer (highly statistically significant) of the most serious offences, such as violence. These findings have been replicated by the Dutch Ministry of Justice; their double-blind study reported a 48% difference between groups. If these studies are widely replicated - and they need to be - we may have a simple and humane means to help reduce and prevent a significant proportion of violence and antisocial behaviour. This should also work in the community, because it is not about where you eat but what you eat. Indeed, criminal justice systems are often over-represented with ethnic minorities, but providing a more nutritious diet is never going to be discriminatory to these young people. The only risk is better health.

Neuroanatomy of financial decisions

INTRODUCTION

Neuroeconomics is a new science that studies the brain processes involved in taking decisions, particularly related to economy and it has experienced an important advance in the recent years due to the development of the new neuroimaging techniques, basically functional magnetic resonance imaging. The aim of this paper it to carry out a review of the literature on the different neurological mechanisms involved in taking financial decisions, the concerned brain structures and the diseases that can affect them.

SOURCES

We made a non systematic review of the literature in primary (PubMed) and secondary (Tripdatabase and Cochrane Library) bibliographic databases. We also used bibliography given by the Asociación Española de Neuroeconomía.

DEVELOPMENT

Brain reward and loss aversion systems suppose a balance that makes us take one or another decision. Dopamine plays an important role on it and several brain structures have been involved in this balance such as the amygdale, the insula, the medial prefrontal cortex, the anterior and posterior cingulated cortex, the accumbens nucleus and the ventral tegmental area. The alteration of this balance may produce inappropriate financial behaviors what may occur in common diseases including depression, mania, alcoholism, gambling and several impulse control disorders.

CONCLUSIONS

Neurologists should define our role in this interdisciplinary field due to the privileged position of our specialty to study how the brain works and due to the potential growing of this science in the near future.