Kynurenine pathway and autism spectrum phenotypes: an investigation among adults with autism spectrum disorder and their first-degree relatives

BACKGROUND

Increasing literature highlighted alterations of tryptophan (TRP) metabolism and kynurenine (KYN) pathway in children with autism spectrum disorder (ASD). However, no study specifically focused on adult samples. Meanwhile, several authors stressed the relevance of investigating neurobiological correlates of adult forms of ASD and of those subthreshold ASD manifestations frequently found in relatives of ASD probands, known as broad autism phenotype (BAP). This work aimed to evaluate circulating levels of TRP and metabolites of KYN pathway in a sample of ASD adults, their first-degree relatives and controls (CTLs), investigating also the correlations between biochemical variables' levels and ASD symptoms.

METHODS

A sample of ASD adults, together with a group of first-degree relatives (BAP group) and unrelated CTLs were assessed by means of psychometric scales. Circulating levels of TRP, KYN, quinolinic acid (QA), and kynurenic acid (KYNA) were assessed in all subjects.

RESULTS

ASD patients reported significantly higher total scores than the other groups on all psychometric scales. BAP subjects scored significantly higher than CTLs. ASD patients reported significantly lower TRP levels than BAP and CTL groups. Moreover, significantly lower levels of KYNA were reported in both ASD and BAP groups than in CTLs. Specific patterns of associations were found between autism symptoms and biochemical variables.

CONCLUSIONS

Our findings confirm in adult samples the presence of altered TRP metabolism through KYN pathway. The intermediate alterations reported among relatives of ASD patients further stress the presence of a continuum between subthreshold and full-threshold ASD phenotypes also from a biochemical perspective.

Circulating Levels of 5-HT and BDNF in Adults with Autism Spectrum Conditions: An Investigation in a Sample of Subjects with Autism Spectrum Disorder, their First-degree Relatives and Controls

BACKGROUND

Several studies investigated circulating levels of serotonin (5- HT) and brain-derived neurotrophic factor (BDNF) in children with Autism spectrum disorder (ASD). More limited literature focused on ASD adults or on populations with subthreshold autism spectrum manifestations, such as relatives of ASD probands. This study aimed to investigate 5-HT and BDNF levels in adults with autism spectrum conditions. Correlations between levels of biochemical variables and ASD symptoms were also evaluated.

METHODS

a sample of ASD adults, their first-degree relatives (Broad autism phenotype, BAP group), and controls were recruited and assessed with psychometric scales. Blood samples were collected from all participants. 5-HT and BDNF levels were measured by means of ELISA kits.

RESULTS

ASD adults showed significantly lower platelet-poor plasma (PPP) 5-HT levels than BAP and control groups. No significant difference was found among groups for PPP BDNF levels and intra-platelet 5-HT levels. 5-HT levels were reported to be specifically correlated with some autism symptoms.

CONCLUSION

This work highlighted the presence in ASD adults of reduced PPP 5-HT levels than in other groups, without significant differences with respect to BDNF levels, supporting the hypothesis that biochemical correlates of ASD in adults may be different from those typically reported in children.

Biochemical Correlates of Video Game Use: From Physiology to Pathology. A Narrative Review

In the last few decades, video game playing progressively became a widespread activity for many people, in childhood as well in adulthood. An increasing amount of literature has focused on pathological and non-pathological correlates of video game playing, with specific attention towards Internet Gaming Disorder (IGD). While many neurobiological studies in this field were based on neuroimaging, highlighting structural and functional brain changes among video game users, only a limited number of studies investigated the presence of biochemical correlates of video gaming. The present work aims to summarize and review the available literature about biochemical changes linked to video game use in IGD patients as well as non-pathological users, and the differences in between. Results may shed light on risks and benefits of video games, providing directions for further research on IGD treatment and, on other hand, on the potential role of video games in therapeutic or preventive protocols for specific conditions.